This literature review is for a project which involves using the same piece of land for setting up a PV farm and performing agriculture/livestock grazing on it. By doing this, the same piece of land can be used to generate electricity and food crops, thus, increasing land use. This setup can prove to be a as it would not only be a steady source of income for farmers but also allow a small area in the vicinity of the PV farm to become self sustaining in terms of electricity.

Initially, this topic would cover the growth of lettuce on a farm having PV panels mounted and the influence of PV panels on the growth pattern of lettuce.

This literature review supported this review article:

This focused article on grape farm potential:

This article discussing the views of farmers on agrivoltaics:

and the views of solar photovoltaic industry persceptives on agrivoltaics:

  • Alexis S. Pascaris, Chelsea Schelly, Laurie Burnham, Joshua M.Pearce. Integrating solar energy with agriculture: Industry perspectives on the market, community, and socio-political dimensions of agrivoltaics Energy Research & Social Science 75, (2021), 102023. https://doi.org/10.1016/j.erss.2021.102023 open access

The life cycle analysis of pasture-based asgrivoltaics for rabbit:

  • Alexis S. Pascaris, Rob Handler, Chelsea Schelly, and Joshua M. Pearce. Life cycle assessment of pasture-based agrivoltaic systems: Emissions and energy use of integrated rabbit production. Cleaner and Responsible Consumption (2021): 100030. https://doi.org/10.1016/j.clrc.2021.100030 academia

Glossary[edit | edit source]

APV - Agrophotovoltaics

AV - Agrivoltaics

AVS - Agrivoltaic Systems

AI - Artificial Intelligence

Amax - Maximum net photosynthesis rate

BOS - Balance of System

BIPV - Building Integrated PV

BG - Bifacial Gain

BF - Bifaciality Factor

CBA - Cost Benefit Analysis

CS - Column Spacing

CPV - Concentrated PV

CT - Customized Tracking

CT - Constant Tilt

CLCA - Consequential Life-Cycle Assessment

DC - Data Center

DRAM - Distributed Recycling and Additive Manufacturing

DSSC - Dye-Sensitized Solar Cells

DHI - Diffuse Horizontal Irradiance

DNI - Direct Normal Irradiance

DAS - Day After Sowing

E - East

EV - Electric Vehicles

FIT - Feed-in Tariff

FS - Full Sun

FD - Full density

GHI - Global Horizontal Irradiance

GMPV - Ground Mounted PV

HD - Half Density

IoT - Internet of Things

ICS - Inter-column-spacing

IRS - Inter-row-spacing

LAOR - Land Area Occupation Ratio

LCA - Life Cycle Analysis

LCOE - Levelized cost of electricity

LAI - Leaf Area Index

LCP - Light Compensation Point

LSP - Light Saturation Point

LER - Land Equivalent Ratio

LPF - Light Productivity Factor

N - North

NPQ - Nonphotochemical Quenching

OPV - Organic PV

POSCAS - Parametric Open-source Cold Frame Agrivoltaic System

PV - Photovoltaic

PPFD - Photosynthetic photon flux density

PPV - Pasture-based Photovoltaics

POA - Plane of Array

PAR - Photosynthetically Active Radiation

PR - Panel Rows

PSN - Net photosynthesis rate

PVSCs - Perovskite Cells

RS - Row spacing

RT - Reverse Tracking

S - South

SCAPV - Spectral-splitting Concentrator Agrivoltaics

STC - Standard Test Conditions

STPV - Semi-transparent Photovoltaics

SVF - Sky View Factor

ST - Standard Tracking

TT - Tracking Treatment

TRF - Spectral total transmittance factor

VPD - Vapor Pressure Deficit

W - West

WTP - Willingness to Pay

See Also[edit | edit source]

Services provided by agrivoltaics are: renewable electricity generation, decreased green-house gas emissions, reduced climate change, increased crop yield, plant protection from excess solar energy, plant protection from inclement weather such as hail, water conservation, agricultural employment, local food, improved health from pollution reduction increased revenue for farmers, a hedge against inflation, the potential to produce nitrogen fertilizer on farm, on farm production of renewable fuels such as anhydrous ammonia or hydrogen, and electricity for EV charging for on- or off-farm use.

Literature Review Page for "Dual Use of Land for PV farms and agriculture literature review"[edit | edit source]

Selected Papers and Literature[edit | edit source]

Combining solar photovoltaic panels and food crops for optimising land use: Towards new agrivoltaic schemes[1][edit | edit source]

Abstract:

Extracting fuel from biomass was put forth as an alternative energy source to dwindling fossil fuel resources. However, this would involve the widespread use of food crops for producing biomass resulting in food shortages as the existing cultivable land on the planet cannot cope with the demand for crops used for food and biomass at the same time. A solution to this problem is an 'Agrivoltaic' system i.e. a combination of PV panels set up on an existing farmland, thus increasing land use. Simulations have shown an increase in land productivity by 60-70%.

Summary:

  • Optimized solar panel orientation is determined by PVsyst software to ensure maximum amount of radiation is tapped by the panels.
  • Panels are mounted at a certain height over the crops to allow mechanical farming equipment to underneath the panels.
  • Difficult to predict the behavior of crops under the shaded area of the PV panel.
  • Experiments have shown that electricity and crop yield of a 100 hectare farm with an agrovoltaic system in place is greater than a 170 hectare farm having separate production.

Productivity and radiation use efficiency of lettuces grown in the partial shade of photovoltaic panels. European Journal of Agronomy[2][edit | edit source]

Abstract: Converting crop lands into PV farms would aggravate the competition for land between food and energy production. Setting up PV panels on top of crop farms shades a part of the crops. In spite of the shading effect, lettuce yields were higher by improving the Radiation Interception Efficiency. The effect of the shade on the lettuce plantation was a reduction in the number of leaves but and increase in the leaf area. This was the adaptation bought about by lettuce to thrive in the shade. A framework is defined based on the adaptive characteristics of crops that thrive in the shade to optimize agrovoltaic systems.

Summary:

  • Lettuce has the ability to adapt to lower light conditions by increasing its capability to harvest light.
  • Similar experiments were done using cucumber, french beans and durum wheat to study the effect of crop rotation on an agrivoltaic system.
  • Agrovoltaic systems can be optimized by plant breeding and making adjustments to PV panels to find the best way to co-produce electricity and food on the same piece of land.

Solar Farms for livestock[3][edit | edit source]

  • Report released by the BRE and National Solar Center of UK stating that PV farms can be set up on lands reserved for livestock grazing.
  • PV farms gives the farmers an economic boost and at the same time does not affect his existing farming practices.
  • The farmer does not need to cut down on the number of grazing animals nor does he have to adjust the grazing frequency of livestock as 95% of the grazing land is unaffected by the PV panels.
  • A PV farm with an output of 4.2 MW was set up in Axminster, Devon, UK. This farm provides electricity as well as fodder for livestock.

To mix or not to mix: evidences for the unexpected high productivity of new complex agrivoltaic and agroforestry systems[4][edit | edit source]

Abstract: Agrivoltaic schemes are profitable, environment friendly and have high levels of production. These schemes have higher volumes of production due to higher land equivalent ratios. Land equivalent ratio(LER) determines the efficacy of a piece of land. It is calculated by the relative yields of the components on the piece of land in question. LER for an agrovoltaic(AV) systerm was the sum of the relative yield of the crop and the relative yield of electricity by the PV panels.

Summary:

  • LER for a 100 hectare AV farm was in the 1.3-1.6 range. Methods to optimize LER were suggested like having a North-South orientation for the crops.
  • PV panels provide constant shading over crops which affect winter crops more as compared to summer crops due to the sunlight demands of such crops. However, the PV panels acts as a protective measure for the crops in the summer from excessive heat and evaporation.
  • More research is needed on the PV panel density depending on the light demands of various crops.

[http://hrcak.srce.hr/index.php?id_clanak_jezik

26832&show=clanak Assessing the land equivalent ratio (LER) of two corn varieties intercropping at various nitrogen levels in Karaj, Iran.][5]====

Abstract:

LER is the ratio of yield of the individual crop in the intercropped land to the yield of each crop in a monocropped land. LER value of 1.0 indicates the same yield from an intercropped and monocropped land. If LER>1.0 indicates a higher yield from the intercropped land and if LER<1.0, the yield of the monocropped land is higher than that of the intercropped land.

Summary:

  • Experiment was conducted to study the effect of two different varieties of corn on land use efficiency with different nitrogen levels
  • LER's for an intercropped land was observed to be 1.066.
  • At different levels of nitrogen content in the soil, LER's were always greater than zero.

How does a shelter of solar panels influence water flows in a soil–crop system?[6][edit | edit source]

Abstract:

Crops can achieve a higher yield under the fluctuating sunlight of an Agrovoltaic system. Under dry climatic conditions, the climatic conditions below the PV panels suggest that the PV panels help in alleviating the water demand by the crops. Water use efficiency can be increased by selecting crops with a rapid soil covering which contributes to a higher amount of light being captured with decreased soil evaporation.

Summary:

  • Shading due to the PV panels resulted in water savings by 14-29% depending on the level of shading.
  • Water demand reduction was achieved by reduction in incident radiation due to the shading effect.
  • Water use efficiency was found to increase for some varieties of lettuce in the shade

Tradeoffs and Synergies between Biofuel Production and Large Solar Infrastructure in Deserts[7][edit | edit source]

Abstract: The paper discusses the setting up of agrivoltaic schemes in arid regions with limited water resources. It discusses about the use of land between panels for growing biofuel plants like Agave which can thrive in dry and arid climate thanks to its water efficient photosynthesis process. Monte Carlo Approach is adopted to measure the uncertainty amongst the various parameters such as variations in the number of solar modules /ha, module efficiency, overall sugar conversion efficiency for agave and number of agave plants /ha. The limited water resources can be used to clean the PV panels as well as watering the plants by directing the water onto the PV panels which would drain off on the agave plants resulting in efficient usage of limited resources. The Agave plants are used in the production of ethanol fuel.

Summary:

  • Revenues from the solar PV per unit of water used was 100 times greater than that of traditional crops. Combination of solar PV and agave resulted in the highest returns per cubic meter of water used.
  • Competition for land for growing biofuel and food crops is reduced and the agave crops can help in reduction of dust collection on the PV panels.

Renewable energy and food supply: will there be enough land?[8][edit | edit source]

Abstract: Renewable energy schemes such as PV farms require large tracts of land to capture sunlight and produce electricity in large quantities. Ideally, the best place to set up PV farms is on barren land. However, if barren land is not available, PV farms have to be set up on cultivable land used for growing food/cash crops. The land required for energy and food production depends on the demand and supply of that particular area. This paper discusses biomass as a short term renewable energy source and the long term potential of solar energy and their effects on limited land resources.

Summary:

  • The food and electricity yield figures obtained are very sensitive to the changes in the estimated input parameters with respect to land requirements.
  • Two scenarios are considered i.e. rich and poor. In the poor scenario, land requirements fall short when biomass is used as an energy source. In the rich scenario, land requirements for food and energy production are satisfied.
  • Widespread changes are to be incorporated into the existing energy infrastructure to accommodate solar PV systems such as storage batteries that store the energy from the PV panels for use at night or during low light periods.

What is the maximum efficiency with which photosynthesis can convert solar energy into biomass?[9][edit | edit source]

Abstract: This paper examines the efficiency of the photosynthesis process at each step in the conversion of solar radiation into biomass and to understand the factors that limit this efficiency. The efficiency of photosynthesis ranges 4.6% to 6%.

Summary:

  • Plants can tap solar radiation between 400-740 nm which is about 48% of the incident solar radiation on Earth.
  • Reasons for losses in the photosynthesis process include reflection and transmission of solar radiation, photochemical process inefficiency, inability of plants to tap solar radiation wavelengths less than 400nm and greater than 740nm, losses due to photo-respiration.
  • Photosynthesis efficiency can be improved by overcoming the photo respiration losses which is the one of the main limiting factors.

Determination of the optimal tilt angle and orientation for solar photovoltaic arrays[10][edit | edit source]

Abstract: The optimum tilt angle of a PV panel can be determined by maximizing the incident solar radiation on the panel subject to minimization of the variance in the power output. The most accurate solar irradiance figures can be selected from existing data for several PV models. A database is then prepared using the existing data for different tilt angles over different periods of time. Meta-models are produced to co-relate the tilt angle with the solar radiations at different times of the day using the data from the database. An optimization problem is then formulated with an objective to maximize solar irradiation on the panel.

Output energy of a photovoltaic module mounted on a single-axis tracking system[11][edit | edit source]

Abstract: This paper deals with the power output of a PV panel installed in Taiwan at different azimuth's and tilt angles. The gain of a single axis mounted panel was compared with that of a traditionally mounted panel. Simulation results show that the optimal tilt angle for observed radiation is flatter than that from extraterrestrial and global radiation.

Summary:

  • Yearly gains from extraterrestrial, global and observed radiation is 51.4%, 28.5%, 18.7% for a module installed at the yearly optimal tilt angle for over a year. Similarly, the gains for a PV panel mounted at the monthly optimal tilt angle are 45.3%, 25.9% and 17.5% respectively.
  • Conversion efficiency of the PV panel mounted at the yearly optimal angle is 10.2%, 9.2% and 8.3% for extraterrestrial, global and observed solar irradiation.
  • The panels can be mounted either at the optimal yearly tilt angle and changed yearly or at the monthly optimal tilt angle which would be changed on a monthly basis.

&arnumber=4522840&isnumber=4522647 A reconfigurable solar photovoltaic array under shadow conditions][12]

Abstract: This paper proposes a method to reconfiguration scheme to reduce the effect of shading on the PV panels. In this method, a smaller reconfigurable adaptive PV bank is connected to a larger fixed PV bank and the maximum power point(MPP) can be tracked with a single MPP tracker. During non-uniform illumination periods, the number of adaptive solar cells connected to the shaded modules depends on the area of shading. A control algorithm is designed to open and close the switches linking the adaptive and the fixed PV modules. The adaptive reconfiguration is bought about by a switching matrix defined in the control algorithm.

Summary:

  • A matrix of switches is used to connect an adaptive PV array to a larger fixed array with an objective to maximize output power in case of non-uniform illumination.
  • An experimental prototype was built and was used to test said algorithms.
  • This configuration is aimed at avoiding the local MPP of each module and focus on the central MPP of the entire array to maximize power output.[13]====

Abstract: The power output of a PV system depends on its nominal power, incoming solar radiation and the losses in the system. It also depends on the other factors such as response to low light response, temperature of modules, light spectrum range, deviation from MPP etc. The paper compares theoretical calculations with actual experiments conducted on the field.

Summary:

  • Theoretical calculations compared with experimental data obtained from PV farms set up at Nicosia, Cyprus and Heraklion, Greece
  • Reduction in power output is due to excess photon concentration caused by overheating cells.
  • Part of the experimental data used was involving PV modules made of multicrystalline modules having stable performance characteristics. For example, amorphous Silicon initially have a higher power output, but the output drops after a few months of use.

On morphogenesis of lettuce leaves in relation to light and temperature[14][edit | edit source]

Abstract: The growth of lettuce under different light and temperature conditions was examined with special emphasis on the head of the lettuce. The number of leaves increased as light intensity and temperature increased. Leaf length and width depend on the environmental conditions i.e high light intensity can cause changes in the width of the leaves. The light intensity in turn is responsible for the temperature effect on the leaves. Similarly, variations in the leaf length are more prevalent at low light intensities i.e they elongate faster at lower light intensities. In contrast, light intensity affects the growth rate and duration of the leaf width which are reduced greatly at low light intensities.

[Are species shade and drought tolerance reflected in leaf‐level structural and functional differentiation in Northern Hemisphere temperate woody flora?][15][edit | edit source]

Abstract: This paper explores the shade and drought tolerances of the leaves of woody species of fauna found in the Northern Hemisphere. A consolidated database was prepared combining the information regarding leaf traits and species tolerances.

Summary:

  • Plant species with higher drought tolerance were resource conserving species with low nitrogen and photosynthetic capacity, longer life span and higher dry leaf mass.
  • Variation in shade tolerance amongst species did not significantly affect the life of the plant.
  • The shade tolerance of the plant depends upon the type of foliage and also suggests a corelation between the leaf structure and the plant's tolerance to environmental conditions.
  • The ability of plant species to develop tolerance against both, drought and shade is an inherent limitation of the plant species in question.

http://www.jstor.org/stable/2401901?seq 1#page_scan_tab_contents Solar radiation and productivity in tropical ecosystems[16][edit | edit source]

Abstract: This paper attempts to develop an approach relating efficiences of dry matter production to factors that determine growth rates. Tropical fauna examples were used to develop this approach.

Summary:

  • Solar energy storage efficiency is expressed as a product of factors describing the dependence of dry matter production, seasonal variation etc.
  • The limitations used to predict crop growth rates are ignorance about the decrease of leaf diffusion resistance, ignorance about the relation between respiration rates and rate of photosynthesis etc.
  • Another limitation for tropical fauna models is the need to do measurements instead of predictions.

Different methods for separating diffuse and direct components of solar radiation and their application in crop growth models[17][edit | edit source]

Abstract: This paper discusses the effect of diffused solar radiation on the dry matter production of leaves under different climatic conditions. Daily and hourly values of incoming direct and diffuse radiation are compared for incorporation into the simulation of wheat growth models.

Summary:

  • By comparison, accuracy of direct and diffuse components of solar radiation varies with changes in climatic conditions.
  • Final yield calculation results are influenced by the methods used to calculate the incoming radiation.
  • Small errors in calculating solar irradiation affects the final yield figures.

Biofuels: environment, technology and food security.[18][edit | edit source]

Abstract: Dwindling fossil fuel resources have pushed up biofuel production levels significantly over the past 10 years and there has been an impetus towards the intensification towards biofuel use. The life cycle analysis helps in understanding the environmental impacts of biofuel production, land requirements and its impacts on food production. Certain protocols have to be established regarding the social impacts of the biofuel production chain.

Summary:

  • In a nutshell, biofuel production and its supporting social and economic factors depend on the development scale of each country.
  • Biofuel cannot be called as a long term replacement for fossil fuels. It can only act as an intermediate solution.
  • Technological development will allow the transition from simple biofuels like bioethanol, biodiesel to cellulosic ethanol, methanol and bio-hydrogen which would alleviate the impact on food production while using large amounts of raw materials at the same time.
  • The by-product obtained from ethanol production from sugarcane bagasse can be used as fodder for livestock, thus benefiting the livestock industry which in turn would reduce the burden on grazing lands and pastures.
  • Regulatory framework imposes limits on land use and also to improve and safeguard the conditions of personnel involved in the biofuel production industry.

Semi-transparent PV: Thermal performance, power generation, daylight modelling and energy saving potential in a residential application[19][edit | edit source]

Abstract: This paper proposes the use of semi-transparent PV panels for residential applications. The characteristics of semi-transparent PV panels are obtained from field tests which give vital information regarding power output, thermal characteristics etc. Semi-transparent PV panels can also be used for daylighting indoor areas, but the saving from this is not very significant as indoor electricity demands are mostly during nights.

Summary:

  • A semi-transparent PV panel with 50% transmission capacity produces a 5.3% reduction in the heating and cooling energy as compared to a normal PV panel.
  • Net energy savings in terms of total energy consumed would be in the range of 3-8.7% by a semi-transparent PV panel.
  • The inner and outer temperatures of the semi-transparent PV panel were measured during summer and winter seasons. Outside temperatures ranged from 35-75oC in winter and summer respectively. Similarly, inner temperatures ranged from 30-40oC in the summer.
  • In terms of power generation by the PV, the paper assumes poly-crystalline Silicon whose power generation capacity deteriorates after a few months.
  • Optimization of PV panels corresponding to the climate and building characteristics contribute to further savings.

Operating temperature of photovoltaic modules: A survey of pertinent correlations[20][edit | edit source]

Abstract: This paper discusses the operating temperature for the best performance of PV panels.

Summary:

  • The temperature of a PV panel can be co-related to factors such as ambient temperature, wind speed, solar radiation.
  • With respect to the weather, temperature rise of the PV cell is sensitive to wind speed changes and practically independent of atmospheric temperature.
  • Temperature of the PV cell depends strongly on the solar radiation on the PV module.

Light distribution, photosynthetic rate and yield in a Paulownia-wheat intercropping system in China[21][edit | edit source]

Abstract: This paper discusses the effect of shading in a Paulownia-wheat intercropped system and its effect on the wheat yields. Factors such as photosynthetically active radiation(PAR), leaf photosynthesis, canopy leaf area index were measured to study the effects of shading on the wheat yields.

Summary:

  • Shading reduced the PAR by 22%, 44% and 56% during the flowering, grain filling and maturing stage.
  • The amount of PAR intercepted in an intercropped system is less than that in a mono cropped system which in turn reduced the number of grains and the grain dry matter.
  • Wheat yields in the intercropped system was less by 51% than that in the mono cropped system.

An overview of the crop model STICS[22][edit | edit source]

Abstract: STICS was a model developed by INRA in 1996. The model simulates crop growth, water balance and nitrogen balance in the soil with respect to the climatic data obtained on a daily basis. This paper discusses the STICS model concerning interractions between the soil and roots and the relation between crop management and the soil-crop system. In addition to this, specific crop species related data is provided by the experts in this field. The paper also discusses the limitations of this model

Advantages:

  • STICS relies on well established data rather than untested assumptions.
  • Adaptability to different crops.
  • Professionals from various related fields can equally contribute to this model, thus evolving as more and more data is provided, making this model grow.

Agrivoltaics in Ontario Canada: Promise and Policy[edit | edit source]

Pearce, J. M. (2022). Agrivoltaics in Ontario Canada: Promise and Policy. Sustainability, 14(5), 3037.

  • Electricity production in Canada via PV < 1% of total energy generation
  • Ontario accounts for the highest share of PV generation - approx. 94%
  • Agricultural Land Use Regulations restrict solar PV deployment
    • Reason - protect farmland/agricultural land from adverse impacts
  • On the contrary, latest studies manifest dual use of land for both PV development and agriculture (known as Agrivoltaics) is entirely possible and even beneficial:
    • Study conducted on pepper, corn and winter wheat showed financial promise; data of different countries utilized
    • Enhanced agricultural production of the crops (especially shade tolerant crops and leafy vegetables)
    • 1% increased PV output since cooler than conventional PV farms
    • Steady stream of revenue for farmers is ensured through electricity
    • Risk of food price fluctuation is alleviated
  • Ontario's three-tiered land-use policy: 1) agricultural land, 2) specialty crop areas and 3) rural area
    • Defines what types of uses will be allowed on each
    • Uses should either be 1) agricultural, 2) agricultural-related and 3) on-farm diversified
    • Current criteria "on-farm diversified" highly restrictive for agrivoltaics

Future Scope

  • Use Ontario's data (especially solar) for analyzing financial gains when using agrivoltaics for pepper, corn and winter wheat farming
  • Regulations being developed on municipal level to be leveraged for agrivoltaic development
  • Consider Agrivoltaics as an agricultural use or agricultural-related use or use on-farm diversified criteria - detailed criteria discussed in paper
  • For crop rotation, agrivoltaic system may have dynamic designs - requires further research
  • Social acceptance in Ontario - requires further research
  • Four policy areas need to be focused for Agrivoltaics:
    • Research & Development
      • Concentrate Ontario's major markets of crops/vegetables
      • Investigate results for target crops and optimize agrivoltaic systems
      • Test "red greenhouse modules" for field and greenhouse deployment
      • Further research on variety of crops and PV systems designs
    • Education/Public Awareness
      • Citizen science approach to be adopted - devices such as parameteric open-source cold frame agrivoltaic system (POSCAS) to be used
      • Conduct open pilot studies
    • Policy Mechanisms to Support Farmers
      • Explicitly define Agrivoltaics
      • Investigate policy of other countries (Japan, U.S etc.)
      • Introduce Feed-in Tariff (FIT)
      • Study Europe's testing methods and utilize to develop similar standards for Ontario's
      • Align provincial and municipal policies
    • Utilize Agrivoltaics as a Trad Surplus with U.S.
      • International power lines connect Canada to U.S.
      • Many states in U.S. have appalling carbon emission
      • Offset emissions and adverse health impacts with renewable solar power
      • Investigate techno-commercial viability

Limitations

  • Farming methods to be revised - additional cost may incur
  • Limited studies conducted on crop rotation
  • Initial costs of deploying Agrivoltaics is higher than conventional farming or PV systems
    • Sustainable business models required to promote Agrivoltaics adoption
  • Cross-border electricity trade may be called into question on political front
  • Social acceptance in Ontario

Parametric Open Source Cold-Frame Agrivoltaic Systems[edit | edit source]

Pearce, J. M. (2021). Parametric Open Source Cold-Frame Agrivoltaic Systems. Inventions, 6(4), 71.

  • Costs of PV are expected to further decline (approx. 60%)
  • Several technical improvements foreseen in PV development
    • Black silicon
    • Bifacial PV
  • Massive areas required for PV deployment coin land use conflicts
  • The issue can be addressed using Agrivoltaics - dual use of of land for PV electrical generation and agriculture
  • Combinations of different edible plants with PV system variables can be overwhelmingly large
  • Method required for agrivoltaic testing for technology optimization
  • Parametric Open Source Cold-Frame Agrivoltaic System (POSCAS) can be utilized for such testing
    • Replaces the cold frame with semi-transparent PV
  • Frame Design
    • Parametric to adopt for different sizes of PV module
    • Design variables can be controlled via parametric OpenSCAD script
    • 3 printable file generated using distributed recycling and additive manufacturing (DRAM)
  • DRAM to fabricate a POSCAS
    • A wide range of thermopolymers may be used
    • Ensures material flexibility and accessibility
  • Module Design
    • Thin film based thickness of active layer adjusts transparency
    • Crystal silicon technology - spacing adjusts transparency
  • Source of raw material has the highest impact on economics of POSCAS - details discussed in research paper
    • Double POSCAS design also alleviates costs
  • Partially transparent PV with colored designs are also being studied
    • Can increase crop yield
    • May be used in greenhouses
  • POSCAS comparison with cold frame and ground-mounted PV systems indicate economic competitiveness
  • Parametric scripts allows variations in POSCAS framework to be customized on any agricultural crop and agrivoltaic system
  • Considering economic viability, researchers can use DRAM POSCAS for agrivoltaic studies

Future Works:

  • Investigate interplay between PV and nanoparticles responsible for spectral shifting in PV with colored designs for a range of crops
  • Identify ideal PV designs for crops using large no. of POSCAS
  • Include accessories (sensors, fans, cameras etc.) to automate care of plants and soil
  • Sensors can be integrated with Internet of Thigs (IoT)/Artificial Intelligence (AI) for data accumulation
    • Data can subsequently be utilized o optimize crop and PV production
  • Verify impact of reflection of solar energy from crops on bifacial PV modules

Crop-specific Optimization of Bifacial PV Arrays for Agrivoltaic Food-Energy Production: The Light-Productivity-Factor Approach[edit | edit source]

Riaz, M. H., Imran, H., Alam, H., Alam, M. A., & Butt, N. Z. (2022). Crop-Specific Optimization of Bifacial PV Arrays for Agrivoltaic Food-Energy Production: The Light-Productivity-Factor Approach. IEEE Journal of Photovoltaics.

  • Agrivoltaics systems installation for improved sunlight sharing between PV arrays and crops
    • Height of PV modules kept between 4 - 7 m above crops
    • Low density - p/h ratio 2 to 3 times of standard PV
  • Paper introduces Light Productivity Factor (LPF) - factor that determines efficacy of light sharing between PV modules and crops
    • For PV only - LPF=1; with Agrivoltaics methodology 1 < LPF > 2
    • Used lettuce, turnip and corn
  • Land Equivalent Ratio (LER) - factor that provides food-energy performance
    • Uses crop yield and electrical output
  • Crop yield is directly proportional to useful photosynthetically active radiation (PAR)
  • Crops have a threshold PAR above which the process of photosynthesis saturates
  • Custom tracking; combination of standard and reverse tacking maximizes PAR requirement
  • Results indicate:
    • For shade tolerant crops, full density PV arrays may be utilized
    • For shade sensitive crops. reduced density PV arrays may be utilized
    • E/W faced vertical PV orientation - preferable fixed tilt scheme
      • Benefits: Low elevation mounting, ease of operation of farm machinery and reduced soil loss

Integration of bifacial photovoltaics in agrivoltaic systems: A synergistic design approach[edit | edit source]

Katsikogiannis, O. A., Ziar, H., & Isabella, O. (2022). Integration of bifacial photovoltaics in agrivoltaic systems: A synergistic design approach. Applied Energy, 309, 118475.

Objective - Devise a multi-scale modelling approach and ascertain optimal topology for APV

  • Idea of APV first coined in 1981
  • Conventional topologies are harmful for crop production
  • Maximum crop productivity (or photosynthesis process) achieved at light saturation point (LSP) - exceeding irradiance alleviates productivity
  • Crops can be classified as C3 & C4 based on carbon assimilation - C3 preferable for APV systems as they saturate at low photosynthetically active radiation (PAR)
  • Plant productivity increased by 5% by using diffusion cover - (cucumbers 8%, roses 10% & tomatoes 8-11%)
  • PV array may reduce soil temperature, crop temperature during noon positively impacting crop productivity
  • Results indicate:
    • Increased irradiance and bifacial gain (BG) by elevated height of PV array; however, main advantage is ease of operation of agricultural machinery
    • Increasing row spacing (RS) reduced electrical output, though, it increased ground irradiation and bifacial gain (BG)
    • South-west orientation augments light penetration in morning while provides shading in noon
    • South facing topologies conducive for cultivation during summer and shade tolerant crops
    • E-W vertical for permanent crops and during winter

Improving Productivity of Cropland through Agrivoltaics[edit | edit source]

Nassar, A., Perez-Wurfl, I., Roemer, C., & Hameiri, Z. Improving Productivity of Cropland through Agrivoltaics.

Objective - Review existing literature of Agrivoltaics and ascertain its applicability in Australia

  • Land equivalent ratio (LER) - parameter used for this study
  • Electrical output of PV system modelled via System Advisory Model
  • Crops (lettuce and silverbeet) grown without shading and under shade (using black tarps) for the study - solar panels not installed
  • Yield produced in Agrivoltaics setting: 72% of lettuce yield compared with traditional farms; 60% of silverbeet yield compared with traditional farms (based on fresh mass)
  • Reduced crop yield most probably due to increased shading

Solar Sharing for Both Food and Clean Energy Production: Performance of Agrivoltaic Systems for Corn, A Typical Shade-Intolerant Crop[edit | edit source]

Sekiyama, T., & Nagashima, A. (2019). Solar sharing for both food and clean energy production: performance of agrivoltaic systems for corn, a typical shade-intolerant crop. Environments, 6(6), 65.

  • Agrivoltaics may have beneficial application for shade-tolerant crops as per past researches
    • Shade tolerance - ability of crops to sustain low levels of light
    • Stilt-mounted agrivoltaics alleviate trade off between crop production and energy generation
    • First agrivoltaic farm experimentation conducted in France with lettuce - research depicted no major impact on lettuce yield
    • Experimentation on durum wheat showed increase (35-72%) in yield
    • 30% increased economic value by employing agrivoltaics on shade-tolerant crops
  • Research conducted on corn in three configurations: traditional farming without solar panel installation (control), low module and high module density
    • PV modules used self-cleaning glass
    • Identical soil, fertilizer and water used
    • Organic farming adopted
    • No pesticides used
    • Feed-in-tariff of 48 yen per kWh
  • Corn yield increased by 5.6% for low density configuration compared with control configuration; total revenue increase 4.7 times larger than control configuration
  • Corn yield reduced by 3.6% for high density configuration compared with control configuration; total revenue increase 8.3 times larger than control configuration
  • High density configuration produced approx. twice electrical output than low density configuration
  • Both low and high density configuration are economically beneficial even if the tariff is reduced to 8 yen per kWh
  • Reasons for high crop yield:
    • Increasing light beyond light saturation point
    • Too high light exposure
    • Reduced water evaporation due to installed PV panels

Future Works:

  • Extend work to shade intolerant crops (watermelon, tomato cucumber, pumpkin, cabbage, turnip & rice)
    • Especially incorporating stilt-mounted configuration
  • Verify results with large sample size
  • Carry out further financial feasibility studies
  • Improved PV designs for enhanced electrical output and agricultural yield

Crop production in partial shade of solar photovoltaic panels on trackers[edit | edit source]

Hudelson, T., & Lieth, J. H. (2021, June). Crop production in partial shade of solar photovoltaic panels on trackers. In AIP Conference Proceedings (Vol. 2361, No. 1, p. 080001). AIP Publishing LLC.

Objective: Ascertain economic viability of crop production under tracking-based PV solar system

  • With PV tracking system, 7 acres land may be required for 1 MW of electrical output
  • Crops experimented: kale, chard, broccoli, spinach, peppers and tomatoes
  • PV panels adopted with tracking system
    • Panel rows (PR) 1 to 7 - crops grown under solar panels
    • Panel row (PR) 8 - traditional crop farming without solar panels (control configuration)
  • Average ambient air temperature increased in morning and reduced in afternoon when compared with control (no panel) configuration
  • No substantial difference in relative humidity in any PR configuration (with or without solar panels)

Results:

  • Biomass accumulated as a function of photosynthetically active radiation (PAR) - varied for different crop type
  • Yield of kale reduced by 23% when compared with control configuration - similar yield production between 55% and 85% of full sun PAR level
  • Yield of chard similar to control when PAR was 85% of full sun values - slight less yield when PAR level was 55% and 62% of full sun numbers
  • Yield of broccoli attainable with at least 85% of full sun PAR - intolerant to high shading
  • Yield of pepper attainable above 55% of full sun PAR - however, quantity will be reduced. For considerable yield, PAR to be greater than 85% of full sun
  • Yield of tomato attainable above 55% of full sun PAR - can tolerate slight shading
  • Yield of spinach extremely sensitive to PAR
  • Maximum daily temperatures 3oC cooler under panel during summer while 2oC warmer during spring
  • For a 24-hour period - temperatures remained warmer in the morning and cooler in the afternoon when compared with full-sun conditions
  • Kale, chard and tomatoes can be cultivated as long as 55% of full-sun irradiance can be attained with PV arrays
  • Cultivation of spinach not advisable considering its high reliance on on solar irradiance

Efficiency Improvement of Ground-Mounted Solar Power Generation in Agrivoltaic System by Cultivation of Bok Choy (Brassica rapa subsp. chinensis L.) Under the Panels[edit | edit source]

Kumpanalaisatit, M., Setthapun, W., Sintuya, H., & Jansri, S. N. (2022). Efficiency Improvement of Ground-Mounted Solar Power Generation in Agrivoltaic System by Cultivation of Bok Choy (Brassica rapa subsp. chinensis L.) Under the Panels. International Journal of Renewable Energy Development, 11(1).

Objective: Investigate improvement in efficiency of PV electrical generation by cultivation of crops beneath the PV modules

  • Study conducted on 25kW power plant using amorphous PV modules; crop selected: bok choy since it can grow well under shade
  • Average solar intensity recorded = 569W/m2
  • Temperature of solar panels was 0.18oC less with crop production beneath when compared with control configuration
  • Crops below solar panel may result in reduced module temperature and higher electrical power output (0.09%)
  • Crop production without solar panels was higher when compared with crop yield with solar panels

Future Works:

  • More crops to be investigated which are favorable for growth under PVs for instance lettuce, spinach, celery, spring onion, ginger, galangal, sweet potato, carrots and chili

Yield Optimization Through Control Strategies in Tracked Agrivoltaic Systems[edit | edit source]

Gfüllner, L., Muller, O., Meier-Grüll, M., Jedmowski, C., & Berwind, M. Yield Optimization Through Control Strategies in Tracked Agrivoltaic Systems.

Objective: To optimize light distribution for gaining maximum crop yield and electrical output via unique solar tracking systems

  • Three strategies were studied:
    • Focus on PV generation - horizontal single axis east west tracking system
    • Focus on plant growth
    • Focus on dual-use (crop production and PV electrical generation)
  • Crop selected: Potatoes; experimental setup was simulation based
  • Results indicate that crop yields are higher in an agrivoltaic system - reason could be increased soil moisture levels

Future Works:

  • Develop a crop model based on hourly timesteps
  • Improved weather files to better investigate impact on crop yields
  • Investigate water resource as a function of optimized tracking system

Comparison of Yield and Yield Components of Several Crops Grown under Agro-Photovoltaic System in Korea[edit | edit source]

Jo, H., Asekova, S., Bayat, M. A., Ali, L., Song, J. T., Ha, Y. S., ... & Lee, J. D. (2022). Comparison of Yield and Yield Components of Several Crops Grown under Agro-Photovoltaic System in Korea. Agriculture, 12(5), 619.

Objective: Investigate crop yields with agrivoltaic systems and compare with control configuration

  • Korea - one of the five top-most importers of fossil fuels
  • Crops experimented: Rice, onion, garlic, rye, soybean, adzuki bean, monocropping corn and mixed planting of corn with soybean
  • Experiment conducted with dummy solar panels
  • Advantages of cultivating crops under PV panels:
    • Effective water/rain distribution and protection against climatic uncertainty
    • Reduced evapotranspiration, soil and crop temperature
    • Increased carbon uptake and water use, land productivity

Results:

  • Yield of rice: Reduced by 18.7% and 8.9% in 2018 and 2019 when compared with open field
  • Yield of soybean: No difference in 2019 while significantly higher in 2020 for open field
  • Yield of adzuki bean: No difference in 2019 while higher in 2020 for open field
  • Yield of garlic and onion: Reduced by 18.7% and 14.6% in 2018-19 and 2019-20 when compared with open field
  • Yield of rye: No significant difference between APV system and open field
  • Yield of corn: No significant difference between APV system and open field
  • Yield of mixed planting of corn with soybean: Reduced when compared with open field
  • Yield of onion: Reduced by 14.4% when compared with open field
  • Yield of garlic: Reduced by 18.7% when compared with open field
  • Conclusive results deduced for corn, rye and rice - for remaining crops, results were inconclusive

Future Works:

  • Research on crop yield for soybean and adzuki bean under APV systems
  • Determine various crop's critical sunlight period requirements to understand their physiological mechanisms
  • Further trials for rice, soybean, adzuki bean, onion and garlic under APV system

Effects of Agrivoltaics (Photovoltaic Power Generation Facilities on Farmland) on Growing Condition and Yield of Komatsuna, Mizuna, Kabu, and Spinach[edit | edit source]

KIRIMURA, M., TAKESHITA, S., MATSUO, M., ZUSHI, K., GEJIMA, Y., HONSHO, C., ... & NISHIOKA, K. (2022). Effects of Agrivoltaics (Photovoltaic Power Generation Facilities on Farmland) on Growing Condition and Yield of Komatsuna, Mizuna, Kabu, and Spinach. Environmental Control in Biology, 60(2), 117-127.

Objective: Investigate crop yields with agrivoltaic systems

  • Crops experimented: Komatsuna, kabu, mizuna and spinach
  • PV panels covered 62% of ground area farm - constant tilt (CT) tracking treatment (TT) as well as control configuration was adopted for study
    • Tracking treatment - single axis
  • Electrical generation income calculated at 37 yen/kWh

Results:

  • Solar radiations transmitted below PV panels
    • TT - 24% of open field radiations
    • CT - 39% of open field radiations
  • Growth rate of komatsuna, mizuna and kabu slower under PV panels - no difference in yields between CT & TT configurations
  • Significant reduction in yield of spinach - not suitable for growth under conditions of alleviated solar radiations
  • Yield, solar radiation, light intensity and air & soil temperature were lower under PV panels
  • Results indicate that
    • Mizuna and kabu are suitable for cultivation in winter season
    • Komatsuna most suitable for growth under PV panels
    • TT conditions suitable for komatsuna and kabu while CT for mizuna
  • Extended cultivation times could result in sufficient yields

Global energy assessment of the potential of photovoltaics for greenhouse farming[edit | edit source]

  • World temperatures may increase to 3.2oC till 2100AD
  • Fossil fuels are responsible for 3/4th of greenhouse gases (GHGs)
  • Estimated world population by 2050 - 9 billion
    • 70% increase in production of food will be needed
  • Energy demands could be met if only 1% of agricultural land is converted to APV
  • The paper discusses a novel Agrivoltaic Model - output: electricity generated and crop photosynthesis rate with regards to Agrivoltaics transparency
    • Three sub models - solar radiation, PV and crop
      • Outputs - PV model: energy harvested with time; crop model: CO2 abosrbed during photosynthesis over time;
  • Experimental locations: El Ejido (Spain), Pachino (Italy), Antalya (Turkey) and Vicente Guerrero (Mexico).
  • PV technology adopted semi-transparent c-Si technology based on opaque cells
    • Reason: High efficiency & reliability
  • Crops selected: 15 species from 5 different families, i.e. Cucurbitaceae, Fabaceae, Solanacae, Poaceae, Rosaceae
  • TRF - Gobal transparency of PV module; TRF value is 0 for fully opaque and 1 for fully transparent
    • Increase TRF - PV energy alleviates while crop performance augments
  • Optimum PV system considered for the application - transparency set as such that net photosynthesis rate (PSN) does not reduce more than 10%
  • Lower photosynthetic photon flux density (PPFD) at which maximum photosynthesis rate (Amax) is achieved, lower will be the TRF resulting in higher PV energy without adversely affecting the crops
  • Solanacae, followed by the Rosaceae and the Curcubitaceae - most suitable families for APV applications in greenhouses

Effects of different photovoltaic shading levels on kiwifruit growth, yield and water productivity under “agrivoltaic” system in Southwest China[edit | edit source]

Jiang, S., Tang, D., Zhao, L., Liang, C., Cui, N., Gong, D., ... & Peng, Y. (2022). Effects of different photovoltaic shading levels on kiwifruit growth, yield and water productivity under “agrivoltaic” system in Southwest China. Agricultural Water Management, 269, 107675.

Objective: Investigate impact of different shading levels on kiwifruit

  • Previous studies indicated no adverse impact of Agrivoltaic setup on tomato and cucumber
  • Experiment conducted using three (03) different densities (19%, 30.4%, 38%) of translucent PV - same compared with control configuration
  • Kiwifruit used for experimentation due to its compatibility with shading for growth
    • Kiwifruit plant is capable to acclimatize to shaded environment
  • Results indicate
    • Solar radiation reduced as compared to control configuration - percentage of reduction increased with increased shading
    • No impact of shading on temperature
    • Relative humidity augmented with increased shading

Leaf transpiration rate, accumulated transpiration, soil evaporation, photosynthetic rate and water use efficiency reduced with increased shading

    • Higher densities (30.4% & 38%) had a significant adverse impact on kiwifruit yield and volume
    • With 19% of translucent PV panels, kiwifruit yield slightly reduced - configuration suitable for kiwifruit growth with Agrivoltaic setup as no major impact on yield

Consumer Study of Agrivoltaics Food Products Including Tomato, Basil, Potato, Bean, and Squash[edit | edit source]

Rogers, M. (2022). Consumer Study of Agrivoltaics Food Products Including Tomato, Basil, Potato, Bean, and Squash (Doctoral dissertation, The University of Arizona).

  • Not much reasearch on senorial charateristics and consumer acceptability of AV based crops
  • For AV to be successful, it must be sustainable (economically, socially and environmentally) - the study explores all three aspects
    • It analysed users' responses to AV configuration and control configuration to gauge any differences/preferences for the crops

Objective:

  • To carry out study of AV crops (tomatoes, basil, beans, potatoes and squash) to ascertain any impact of growth conditions on sensory charatecteristics
  • Testing techniques employed
    • Triangle test - determine perceptible difference between samples grown in different growth conditions
    • Paired comparison test - determine difference in sensory attributes between AV and control growth configuration
    • Paired preference test - determine preference of changed/modified product vs established product
    • 5-point ordinal Likert scale
    • Multinomial logistic regression and logistic regression

Economic Sustainability:

  • AV have no major history of profitability
  • Installation and maintenance costs are high
  • Subsidies and amneties for AV could promote the technology
  • Fair wages for farm workers to be ensured or its growth

Social Sustainability:

  • Producers/suppliers of AV can promoted social sustainability of the technology by ensuring fair wages to workers, healthcare benefits, safe working environment, fair pricing and preserving cultural heritage
  • Consumers can do the same by reducing waste, eating locally and seasonally
  • AV provides safer environment to workers by protecting them from excessive heat
  • Electrical risk is associated with AV - threat to human and animal life
  • Local workforce and involvement to be enhanced to develop AV technology
  • Diversification of workforce (gender, races etc.) is also imperative to promote AV technology

Environmental Sustainability:

  • Potential environmental issues associated with AV: soil erosion, PV waste and pollinator pattern
  • Rainwater collection system can reduce the risk of soil erosion
  • Proper soil selection is also imperative to protect cropland beneath PV
  • To reduce PV waste, it can be recycled

Conclusion:

  • No major differences/preferences were reported by the tasters between AV-based crops and control grown crop
    • Fruits more likely to be identified as different than vegetables
    • Only beans were preceived as different from the tests
  • Individuals were also inclined to pay more for AV based crops

Future Works

  • Carry out similar research at other geographical locations with variety of crops
  • Reward participants of the study
  • Record data at different times of the season
  • Consider participants prior knowledge and perceptions about solar industry for better understanding of their responses and their utilization in the study
  • Larger sample size for similar research

Increasing the total productivity of a land by combining mobile photovoltaic panels and food crops[edit | edit source]

Valle, B.; Simonneau, T.; Sourd, F.; Pechier, P.; Hamard, P.; Frisson, T.; Ryckewaert, M.; Christophe, A. Increasing the Total Productivity of a Land by Combining Mobile Photovoltaic Panels and Food Crops. Applied Energy 2017, 206, 1495–1507, doi:10.1016/j.apenergy.2017.09.113.

  • Crop Type: Lettuce
  • Fixed PV type; inter row spacing 0.80 for half density (HD) and 1.6m for full density (FD)
  • Tracking PV; two types (ST: normal PV tracking; CT: PVs move parallel to sun rays except between 11AM and 03PM during which the operation was normal as for normal solar PV tracking)

Results:

Radiation at Plant Level:

  • Less for all systems when compared with control systems (without PV modules)
  • When compared with ST and HD, CT showed 30 and 40% more radiation
  • HD configuration manifested 8% and 23% higher radiations in spring and autumn whenc compared with FD
  • For overcast conditions, there was less effect of PV system configuration on radiations received below the panels due to dominance of diffuse radiations

Leaf temperature:

  • No major difference in control and agrivoltaic configuratoin for cloudy days or morning/evening times
  • Major difference during sunny days
  • However, 24h average did not show major difference in sunny or non-sunny days

Plant Dry Mass:

  • Reduction observed between up to 18%when compared with traditional crops - more important in spring and summer seasons than in autumn

Leaf Number and Project Leaf Area:

  • No. of leaves reduced when compared with full sun (FS) conditions

Specific Leaf Area and Leaf Dimensions:

  • Increased generally for all the configurations when compared with FS conditions

Electricity:

  • 2.7 (CT) to 4.8 (ST) times higher for sunny days as compared to overcast days
  • Total energy production for unit land area for ST 74% higher than HD
  • Total energy production for CT reduced 23% when compared with HD
  • For overcast conditions, electricity generaiton for ST and CT was higher
  • Total energy production for ST 65% to 90% higher than FD

Land Equivalent Ratio (LER):

  • LER was found to be between 1.25 and 1.5

Biomass:

  • For ST, in summer and spring, biomass was 67% to 77% of biomass produced in FS
  • For CT, biomass was 77% for Madelona and 99% for Kiribati
  • Thinner, longer and narrower leaves resulted in AV systems compared to FS – thus, higher SLA. This compensated partial shading due to more area for light interception.
  • Kiribati performance better than Madelona.
  • In CT crop yield 71% in spring and 82% in summer compared with FS.

Agrivoltaic systems to optimise land use for electric energy production[edit | edit source]

Amaducci, S.; Yin, X.; Colauzzi, M. Agrivoltaic Systems to Optimise Land Use for Electric Energy Production. Applied Energy 2018, 220, 545–561, doi:10.1016/j.apenergy.2018.03.081.

  • Crop Type: Maize
  • Two difference schemes (based on solar PV panels densities) for fixed and solar tracking employed
  • Solar Tracking 1: Total panels surface/soil surface = 0.13; Electricity: 17.42 kWh/m2; Grain Yield: 735 g/m2; Biomass Yield: 2091 g/m2; LER based on biomass yield: 1.28
  • Fixed Tilt 1: Total panels surface/soil surface = 0.13; Electricity: 17.42 kWh/m2; Grain Yield: 793 g/m2; Biomass Yield: 2178 g/m2; LER based on biomass yield: 1.23
  • Solar Tracking 2: Total panels surface/soil surface = 0.36; Electricity: 17.42 kWh/m2; Grain Yield: 743 g/m2; Biomass Yield: 2131 g/m2; LER based on biomass yield: 2.02
  • Fixed Tilt 2: Total panels surface/soil surface = 0.36; Electricity: 17.42 kWh/m2; Grain Yield: 781 g/m2; Biomass Yield: 2202 g/m2; LER based on biomass yield: 1.74
  • Full light biomass yield: 2080 g/m2.

Crop production in partial shade of solar photovoltaic panels on trackers[edit | edit source]

Hudelson, T.; Lieth, J.H. Crop Production in Partial Shade of Solar Photovoltaic Panels on Trackers. AIP Conference Proceedings 2021, 2361, 080001, doi:10.1063/5.0055174.

  • Crop: Kale, Chard, Broccoli, Tomato, Spinach, Peppers
  • Solar tracking configuration; inter-row spacing when the panels were flat was 5.7 meters
  • Values of PAR reduced to 7% of control in PR1 and PR7, 62% and 55% in PR2 and PR6 and 85% in PR3 and PR5
  • Across the 24-hour day, average ambient air temperatures beneath the PV panels for all locations increased during morning and decreased in afternoon when compared with control configuration.
  • No major difference was observed in relative humidity
  • No impact on Kale yield when PAR values are between 55% and 85% of FS conditions; yield was 23% less than control configuration
  • Yield similar to control configuraiton is observed when PAR is 85% or more of full sun conditions
  • 85% or more PAR values are required referenced to FS for broccoli to have harvestable yield
  • More yield observed for peppers when PAR was 85% or greater - although harvestable biomass is observed above 55% PAR

Effects on Crop Development, Yields and Chemical Composition of Celeriac (Apium graveolens L. var. rapaceum) Cultivated Underneath an Agrivoltaic System[edit | edit source]

Weselek, A.; Bauerle, A.; Zikeli, S.; Lewandowski, I.; Högy, P. Effects on Crop Development, Yields and Chemical Composition of Celeriac (Apium Graveolens L. Var. Rapaceum) Cultivated Underneath an Agrivoltaic System. Agronomy 2021, 11, 733, doi:10.3390/agronomy11040733.

  • Crop: Celeriac
  • PAR reduced about 30% for AV systems
  • Crop height and leaf area index incrasaed for shaded conditions
  • Under AV, in 2017, yields were lowerer when compared with 2018 - possible reason hot and dry weather made lower soil temperatures and lower PAR favorable for plant growth
  • Celeriac could be a good option for cultivation under AV

Agrivoltaics provide mutual benefits across the food–energy–water nexus in drylands[edit | edit source]

Barron-Gafford, G.A.; Pavao-Zuckerman, M.A.; Minor, R.L.; Sutter, L.F.; Barnett-Moreno, I.; Blackett, D.T.; Thompson, M.; Dimond, K.; Gerlak, A.K.; Nabhan, G.P.; et al. Agrivoltaics Provide Mutual Benefits across the Food–Energy–Water Nexus in Drylands. Nat Sustain 2019, 2, 848–855, doi:10.1038/s41893-019-0364-5.

  • PV panel efficiency deteriorates 0.6% as temperature increases 1oC.
  • Large PV arrays can accumuate heat which can cause further deterioration in performance
  • Fixed PV used for experimentation
  • PAR for control configuration as higher than AV
  • Lower PAR in AV resulted in lower temperatures during day approximately 1.2 + 0.3 oC while night temperatures were higher 0.5 + 0.4 oC
  • Vapor pressure deficity (VPD) was lower (0.52 + 0.15 kPa) in AV
  • Yield: Chiltepin fruite three times and tomato two times higher under AV while nearly equal yield for jalapeno
  • Soil moisture: 5% greater and 15% greater than control configuration when irrigated every day and every second day respectively. Mositure was found higher in AV after 2 days of irrgation than the driest points in control configuraiton afte daily irrigation.
  • Electricity: Temeprature reduction resulted in 3% increase in generation between May and July while for the whole year, the advantage gained was 1%

Remarkable agrivoltaic influence on soil moisture, micrometeorology and water-use efficiency[edit | edit source]

Adeh, E.H.; Selker, J.S.; Higgins, C.W. Remarkable Agrivoltaic Influence on Soil Moisture, Micrometeorology and Water-Use Efficiency. PLOS ONE 2018, 13, e0203256, doi:10.1371/journal.pone.0203256.

  • Crops: Pasture
  • Design : East-west oriented, tilt of 18 degrees, inter-row spacing of 6m
  • PV system capacity: 1435 kW
  • Mean Temperature: Major difference in temperature closest to PV panel
  • Relative Humidity/Wind Speed: Major difference in readings for different heights
  • Solar Radiation: Major reduction below the solar panel installed
  • Wind Direction: Wind direction is reoriented for AV configuration - south to north; while for control it is oriented at different directions
  • Soil Moisture: Reduces rapidly in the area between the panels for AV configuration than the shaded or control configuration. Ideally, it should be the same as for control configuration - reason could be reduced view factor and long wave radiation transfer. Shaded area has more moisture in general than control configuration and the alley area between the panels for AV
  • Yield: 126% more biomass yield is observed for shaded area when compared with alley area for AV and 90% more for when compared with control configuration
  • Water Efficiency: 328% more efficient than control configuration

Performance of Agrivoltaic Systems for Shade-Intolerant Crops: Land for Both Food and Clean Energy Production[edit | edit source]

Sekiyama, T. Performance of Agrivoltaic Systems for Shade-Intolerant Crops: Land for Both Food and Clean Energy Production. 2019.

  • Crop: Corn
  • Three configurations - control, low density AV (1.67m) and high density AV (0.71m)
  • System capacity: 4.5 kW
  • Biomass in low density AV configuration was 4.9% higher than control and corn yield per sq meter was 5.6% higher.
  • Revenue from high density system and low dnesity system was 8.3 times and 4.7 times larger.
  • Electricity production from high density system was twice the amount of low density system.

A new predictive model for the design and evaluation of bifacial photovoltaic plants under the influence of vegetation soils[edit | edit source]

Rodriguez-Pastor, D.A.; Ildefonso-Sanchez, A.F.; Soltero, V.M.; Peralta, M.E.; Chacartegui, R. A New Predictive Model for the Design and Evaluation of Bifacial Photovoltaic Plants under the Influence of Vegetation Soils. Journal of Cleaner Production 2023, 385, 135701, doi:10.1016/j.jclepro.2022.135701.

  • For the anlaytical model, view factors, heat transfer calculations and electrical model are considered
  • Study performed on 11.24 MWp system; solar tracking based and the distance between the trackers i 9.7m
  • Electricity generation increased for the crops because:
    • Decreased module temperatures;
    • Increased albedo
  • Hourly analysis shows module temperautre 1 to 1.5oC lower in AV configuration
  • Difference between energies was around 250 kWh for AV and control configuration

Key Word - Agrivoltaic Electric[edit | edit source]

Agrivoltaic Engineering and Layout Optimization Approaches in the Transition to Renewable Energy Technologies: A Review[edit | edit source]

Reasoner, M.; Ghosh, A. Agrivoltaic Engineering and Layout Optimization Approaches in the Transition to Renewable Energy Technologies: A Review. Challenges 2022, 13, 43, doi:10.3390/challe13020043.

  • Crops: Lettuce and tomato
  • Tracking: Comparison of N/S and E/W tracking on PAR - E/W tracking gives best electricity output while E/W fixed gives best PAR
  • PV Cell Type: Different types being used including high concentration PV, ulta-thin amorphous germanium and semi transparent PVs
    • Tuning the transmitted light is feasible, however, maximum efficiency achieved is 5%
  • Half density provides better output than full density but only in summers
  • Shading under PV was found between 18% and 58% for vertical PVs with different row spacing
  • Spacing increases crop productivity - half density provides 24% better output
  • Vertical bifacial PVs improves spacial distribution of sunlight as well as LER
  • Spacing between the panels (not inter-row spacing) also decreased shading
  • Checkerboard arrangement of PV panels reduces irradition losses by 6%
  • Higher density tracking increased yield of maize as opposed to fixed configuration which decreased it
  • Bifacial optimum spacing is 9.7m for oats and potatoes
  • Crop production
    • Alfalfa - Oregon, US; 2.63$ per acre improvement
    • Basil - Italy; 15% decrease in yield but 2.5% financial benefit
    • Bok Choy - Thailand; PV system efficiency but loss in production
    • Canola - Spain; decreased yield 20%
    • Carrots - Spain; decreased yield 10%
    • Celeriac - Germany; 12 % increased yield; 1.76 LER
    • Chiltepin Pepper - AK, USA; 3 times greater production with same water efficiency
    • Clover grass - Germany; decreased production 8% in 2017 adnd 5 % in 2018
    • Fava Bean - Spain; no impact on yield - same
    • Grape
      • Korea; no difference in yield but harvest delayed by 10 days
      • India; same yield and 15 times economic advantage
    • Jalapeno - Arizon, USA; same yield with 157% water efficiency
    • Melon - Spain; Reduced yield 17%
    • Misai Kuicy - Malaysia; no impact on yield, however, 14.27% efficiency improvement of PV
    • Onion - Spain; reduced yield of 6%
    • Potato
      • Germany; reduced harvest yield of 10% in 2017, 11% increase in 18% while LER was 1.76
      • Spain; 23% decrease in crop yield
    • Rice - Japan; limit for shading is 27-39%
    • Soybeans - North Carlolina, US; 2.473$ per acre benefit
    • Spinach - Italy; 26% decrease in marketable yield but 35% economic benefit
    • Tomato
      • Arizon, US; twice production with 65% efficiency of water
      • Oregon, US; 51% reduction under the panelwhile between the panel the reduction was 39%
      • Spain; 5% decrease in crop yield
    • Wheat - Germany; 19% reduction in 2017 while 3% increase in 2018 in harvest yield while LER was 1.71
  • Dual axis tracking is the most beneficial - highest electricity output without any adverse impact on crops
  • South-facing E-W axis tracking gives best result for electricity output with minimal impact on yield

Agrivoltaic Systems Enhance Farmers’ Profits through Broccoli Visual Quality and Electricity Production without Dramatic Changes in Yield, Antioxidant Capacity, and Glucosinolates[edit | edit source]

Chae, S.-H.; Kim, H.J.; Moon, H.-W.; Kim, Y.H.; Ku, K.-M. Agrivoltaic Systems Enhance Farmers’ Profits through Broccoli Visual Quality and Electricity Production without Dramatic Changes in Yield, Antioxidant Capacity, and Glucosinolates. Agronomy 2022, 12, 1415, doi:10.3390/agronomy12061415.

  • Bifacial modules may provide 20% higher capacity for PV applicaitons
  • Broccoli plant was selected for experiment
    • Higher vitamin C than broccolis and cabbages
    • Anticancer compounds
  • Major variation in antioxidant capacity between seasons but no disparity in control and AV configurations
  • Lower PPFD (AV configuration) may be more conducive for broccoli growth than pepper
  • Average soild temperature found higher than AV configuration
  • Reduction in yield was 10% for simple AV configuration and 16% for AV + additional shading when compared with control configuration
  • Reduction in PPFD was 58% for simple AV configuration and 41% for AV + additional shading when compared with control configuration
  • Yearly financial advantage from solar energy was 10.4 times than economic benefits from broccoli

Current status of agrivoltaic systems and their benefits to energy, food, environment, economy, and society[edit | edit source]

Kumpanalaisatit, M.; Setthapun, W.; Sintuya, H.; Pattiya, A.; Jansri, S.N. Current Status of Agrivoltaic Systems and Their Benefits to Energy, Food, Environment, Economy, and Society. Sustainable Production and Consumption 2022, 33, 952–963, doi:10.1016/j.spc.2022.08.013.

  • Objective: To determine the best configuration fo fixed bifacial based AV configuration
  • EW configuration provides the best shading schedule and most predictable microclimate
  • Plantation between Arrays
    • Water for cleaning PV used for irrigation of aloe vera
    • Economic value of AV configuration was 15 times more than control configuration for grape farming
  • Animal grazing and PV
    • Fish growth improved and PV system efficiency improved by 30% (due to reduced temperature of panels)
    • Efficiency of PV panels improve when coated with AlO or tantalum pentoxide
    • Sheep spent 70% of time under th shades of PVs when solar irradiation was 800 W/m2
    • Dry mass of lettuce cultivated under solar tracker based AV was almost equal to control agrivultural configuration
  • Power
    • Temperature for panels installed in AV configuration was 2.8oC and 0.71oC lower for sunny and cloudy days when compared with normally installed PV panels
    • Increased PV efficieny for AV configuration - 1.13%-1.42% for sunny days and 0.28% -0.35% for cloudy days
    • Increase energy for AV configuration - between 3.05% and 3.2%
    • Another study showed 0.18oC decrease in PV panels temperature for AV scheme while 0.09% voltage and power output improvement
  • Crop
    • Decrease in yield observed - 3.98% to 91.30%
    • One study found no difference in crop yield quality
  • Land Equivalent Ratio
    • LER for AV system were found between 1.29 and 1.73
  • Greenhouse Gas Emissions
    • Agricultural sector contributes 10-14% of total increase in greenhouse gases glabally
    • 1500kW PV system reduces greenhouse gases by 1549tCO2e/year
  • Finances
    • Simple payback period for AV system - between 5 year and 8 years
    • Installation of PV for an AV system could generate 117,000 empolyment opportunities in US for a 20 year timeframe

Future Works

  • Corrosion and lifetime analysis of PV racking materials/structural materials for use in AV configuration - considering more moisture/water

Integration of bifacial photovoltaics in agrivoltaic systems: A synergistic design approach[edit | edit source]

Katsikogiannis, O.A.; Ziar, H.; Isabella, O. Integration of Bifacial Photovoltaics in Agrivoltaic Systems: A Synergistic Design Approach. Applied Energy 2022, 309, 118475, doi:10.1016/j.apenergy.2021.118475.

Plant Growth

  • Crops may be categorized as C3 or C4 based on PAR levels - C3 crops saturate earlier than C4 and hence, more suitable

Diffuse Light

  • Short and compact canopies provide substantial shading - compensation through diffuse radiation can be performed
  • Lower Leaf Area Index (LAI) provide least shading - no requirement for diffuse cover
  • Light diffusion film can improve crop production by 5% - For cucumber 8%, roses 10% and tomatoes 8-11% improvement

Effect of Plant Canopy

  • Mean daily air tempeature - no major difference when compared with FS conditions
  • Reduced soil temperature observed for shaded regions
  • Low temperature observed for crops during the day while higher at night

Elevation

  • Bifacial gain, elevation and energy output showed a linear trend

Transparency

  • Augmenting transparency in module by 50% improved rear irradiance gain by 10%
  • PV temperatures also reduce due to better heat dissipation

Tilt

  • Optimum - latitude of slightly higher

Azimuth

  • E-W vertical performs better than N-S for albedo and latidues values of 0.5 and 30o

Row Spacing

  • Logarithmic trend observed for bifacial gain with increased spacing between row - changes from 27.7 to 31.5 for an albedo of 0.5 and spacing of 2.5m
  • Irradiance increased by 1% S-N and 7.9% E-W as inter row spacing changes from 2.9 to 3.9m
  • N-S generates 32% more electrical output
  • With an inter-row spacing of 2m, E-W orientation results in10-20% more electrical ouput when compared with a monofacial optimally inclined system

Soiling Loss

  • 0.35%/day in Chile; almost none for E-W vertical

Results

  • Linear increment upto 3.4% observed for annual and average ground irradiation as the array height increased from 2m to 7m
  • Increasing the row-spacing by twice increased ground irradiation from 58.1% to 79.6% for south oriented panels at a tilt of 35o
  • Increasing the row-spacing for E-W vertical orientation increased ground irradiation from 75.9% to 88.6%
  • E-W orientation improves light penetration especially during winter season - hence, preferable for permanent crops; N-S suitable for summer
  • For conventional PV modules - S-N orientation is preferreable for shade tolerant crops; E-W vertical improves improves sunlight intensity during winters, hence, compatible with permanent crops while E-W wings for crops that require shading mid-day
  • Increasing transparenecy from 7% to 55% incrases bifacial gain by 3.8%

Progress and challenges of crop production and electricity generation in agrivoltaic systems using semi-transparent photovoltaic technology[edit | edit source]

Gorjian, S.; Bousi, E.; Özdemir, Ö.E.; Trommsdorff, M.; Kumar, N.M.; Anand, A.; Kant, K.; Chopra, S.S. Progress and Challenges of Crop Production and Electricity Generation in Agrivoltaic Systems Using Semi-Transparent Photovoltaic Technology. Renewable and Sustainable Energy Reviews 2022, 158, 112126, doi:10.1016/j.rser.2022.112126.

  • For rice output to be at least 80% of control, shading rate was between 27% and 39%
  • No significant impact on greenhouse microclimate if 40% of roof area covered by PVs

Integration of c-Si Semi-transparent Photovoltaics (STPV)

  • System
    • South-facing greenhouse; crop: lettuce and tomatoes; cover ratio: 20%
  • 35-40% reduction in light and reduced air temperature, no major difference in growth of lettuce/tomatoes
  • Payback period was found to be 9 years
  • STPV configuration provides better yield than checkerboard arrangement

c-Si STPV

  • Diffuse films with STPV modules may improve agricultural yield as more light reaches lower parts of the plant
  • When compared with traditional PVs, better light penetration and higher yields achieved

Thin Film PV

  • Mostly used in greenhouses due to lower performance and high costs

Organic Photovoltaics (OPV)

  • Uses UV or IR for electricity and lets visible spectrum to pass
  • Can be used as a substitute for plastics in greenhouses and in place of foils /nets for open spaces
  • OPVs offer improved light control and better integration with environment
  • OPVs less stable
    • Hence, not much commercial appetite
    • Lowers lifetime when compared with c-Si PV
  • More research required to understand crop response

Dye-sensitized Solar Cell (DSSC)

  • Electrochemical device using light-absorbing dye molecules to generate electricity from irradiation
  • Provide selective spectrum absorption characteristic - similar to OPVs
  • More aesthetic/more colorful - perhaps better social acceptance; flexible and lightweight
  • Ability to operate under diffuse light conditions
  • Through application of light scattering layer, light absorption can be increased (sunlight scatter when it reaches to the canopy)

Concentrated PV (CPV)

  • Diffuse sunlight passes through CPV - can be used for AV applications
  • Can generate higher electricity when compared with c-Si PV for the same diffuse light
  • More research required to understand crop response

Wavelength Selected PV (WSPV)

  • Can substitute plastic and glass coverings for greenhouses
  • Initial studies indicate better plant response for WSPV

A review of research on agrivoltaic systems[edit | edit source]

Mamun, M.A.A.; Dargusch, P.; Wadley, D.; Zulkarnain, N.A.; Aziz, A.A. A Review of Research on Agrivoltaic Systems. Renewable and Sustainable Energy Reviews 2022, 161, 112351, doi:10.1016/j.rser.2022.112351.

  • France - no significant difference observed between AV and control configuration for mean daily air temperature
  • Germany - reduced air temperature under PV when compared with control configuration
  • Some researchers found similar temperature while others found major difference in humidity and daily air temperatures - reason could be ground clearance, confiiguration or shading pattern
  • Wind speed - wind speed found different at different ground clearance levels while wind direction was random
  • Soil Temperature - soil temperature reduces under the PVs when compared with open conditions
  • Daily Temperature - major disparity in mean daily air temperature for AV and control configurations - for AV slightly lower
  • Humidity - difference in humidity observed - during summer, daily change in humidity was less under PVs
  • Wind speed - large AV systems can change wind profile
  • Changing soil temperatures impacted the leaf emission rate in cucumbers and lettuce
  • Soil Moisture - changes observed due to varying shades
  • Crop Temperature and Growth Rate - crop temperature did not change for AV or control configurations while the growth was similar as well
  • Vapor Pressure Deficit - VPD lower (0.52 + 0.15 kPA) in AV system when compared with open air
  • PAR - Quite low for shaded regions in AV configuration
  • For tomato, 50% of incoming radiation makes up the required PAR
  • In situation of water scarcity, maize yield is found to be better in AV configuration
  • Perennial pasture perform satisfactorily in AV configurations
  • Crops perform better under under amorphous silicon (a-Si) and cadmium telluride (CdTe) PV when compared with mc-Si (crystalline silicon) PVs
  • Efficiency of PV reduced by 0.5% as air temperature increases by 10oC
  • PV temperature are found 8.9 + 0.2 oC less in AV configuration than for conventional PV plants
  • Recommended ground clearance - 4m; while inter-row spacing - 6.4m
  • Approx. 2% of agricultural land is covered with installation for AV - impact crop yield
  • Irradiation reduces 15-40% in AV configuration
  • Lettuce performs satisfactorily till 30% reduced irradiation
  • Life Cycle Analysis (LCA) - payback period is 9 years for AV, 8 for ground-mounted and 6 for roof-mounted

Future Works

  • Economics of AV - detailed modelling

Agrivoltaic systems have the potential to meet energy demands of electric vehicles in rural Oregon, US[edit | edit source]

Agrivoltaic Systems Have the Potential to Meet Energy Demands of Electric Vehicles in Rural Oregon, US | Scientific Reports Available online: https://www.nature.com/articles/s41598-022-08673-4 (accessed on 26 February 2023).

  • 25% of CO2 emissions world-wide comes from fossil fuels
  • Range anxiety is a mjor challenge for Electric Vehicles (EVs) expansion/adoption
  • Customers are comfortable if the distance between EV chargin stations is below 5 kms
  • 3% of land is required in Oregon, US to power 86% of rural highway access points through AV

Future Works

  • Similar study for Canadian provinces

Agrivoltaic system: Experimental analysis for enhancing land productivity and revenue of farmers[edit | edit source]

Giri, N.C.; Mohanty, R.C. Agrivoltaic System: Experimental Analysis for Enhancing Land Productivity and Revenue of Farmers. Energy for Sustainable Development 2022, 70, 54–61, doi:10.1016/j.esd.2022.07.003.

  • System: 0.675 kWp; 11m2 of land; gap between solar panel - lower row 0.01m and upper row 0.65m; inter-row spacing 3.1m
  • Location: Odisha, India
  • 70-75% shading from AV observed - microclimate for turmeric growth maintained while air temperature under PV reduced 1 to 1.5 oC when compared with ambient
  • Irradiation between the panels similar to control configuration
  • Economically advantageous to have AV

Results:

  • Annual electricity output for AV - 1120 kWh; without crops - 1024 kWh
  • Turmeric yield for AV - 16 kg; without AV - 18.5 kg
  • LER for AV with turmeric cultivation - 1.73

Keyword: Agrivoltaic

Computational fluid dynamics modelling of microclimate for a vertical agrivoltaic system[edit | edit source]

Zainali, S.; Qadir, O.; Parlak, S.C.; Lu, S.M.; Avelin, A.; Stridh, B.; Campana, P.E. Computational Fluid Dynamics Modelling of Microclimate for a Vertical Agrivoltaic System. Energy Nexus 2023, 9, 100173, doi:10.1016/j.nexus.2023.100173.

  • World's total primary energy consumption - 165,319 TWh (2021)
  • AV system investigated in Sweden; vertical E-W configuration and bifacial PVs used
  • Solar irradiance estimated from CFD simulations were near to the measured values although undervalued (especially for cloudy conditions)
  • Solar insolation on ground changes massively for vertical AV systems - found a reduction of 38% on a given day
  • Temperature of PV module can also be determined from CFD model - error between 0-2oC as compared to thermography
  • Ground temperature may also be predicted from CFD model - error less than 1oC
  • 0.3oC increase in air temperature also observed for AV

The development of utility‑scale solar projects on US agricultural land: opportunities and obstacles[edit | edit source]

Daniels, T.L. The Development of Utility-Scale Solar Projects on US Agricultural Land: Opportunities and Obstacles. Socio Ecol Pract Res 2023, doi:10.1007/s42532-023-00139-9.

  • Large solar farms need to be less than one mile in distance from substation/transmission line to ensure economic viability
  • AV increases the cost of a conventional solar project by 5 to 50% considering height of stilt mounted panels
  • To protect farmland, the developer may be required to fill a bond for restoration works - might improve social acceptance
  • A mitigation levy can be introduced for any farmland transformed to solar farm - restricting only solar development
  • Crop yield must be at least 66% in Germany for AV; in France, 80%

Crop-driven optimization of agrivoltaics using a digital-replica framework[edit | edit source]

Mengi, E.; Samara, O.A.; Zohdi, T.I. Crop-Driven Optimization of Agrivoltaics Using a Digital-Replica Framework. Smart Agricultural Technology 2023, 4, 100168, doi:10.1016/j.atech.2022.100168.

  • Model agrivoltaic system through digital replica and genomic optimization framework
    • Incident solar radiations are simulated for an identified crop, location and season
    • Incident light abosrbed by PVs and crops are estimated
  • The estimates are input into crop model for ascertaining AV performance
  • Genomic optimization technique is used to come up the most suitable agrivoltaic design for a particular crop, season and location

Method

  • Solar angles are estimated from pysolar
    • Irradiation acquired from weather files
  • SIMPLE crop model used in the paper
    • Growth stage of crop is determined based on crop temperature (cumulative thermal time)
    • Daily biomass growth is ascertained using the growth stage and incident along with other variables
  • Light is used to estimate the irradiation levels absorbed at ground as well as by solar PVs
  • The reference and agrivoltaic crop yield is estimated using SIMPLE model throught the estimated irradiation
  • Structure is developed using Python 3.9
  • A secondary program is then used to determine the optimal configuration which takes inputs from ligth model, crop model and other sources
  • The secondary program estimates crop biomass, evapotranspiration, water and light for different designs for optimization

Results

  • The best design was with close to vertical panels
  • 28.9% reduction is cost esimtated from the best configuration
  • Reference yield: 1.70 tons/acre; AV yield: 1.43 tons - 18% loss in AV design

The potential for agrivoltaics to enhance solar farm cooling[edit | edit source]

Williams, H.J.; Hashad, K.; Wang, H.; Max Zhang, K. The Potential for Agrivoltaics to Enhance Solar Farm Cooling. Applied Energy 2023, 332, 120478, doi:10.1016/j.apenergy.2022.120478.

  • Objective: Understanding the implication of changing height of PV panels, albedo and evapotranspiration
  • Study conducted for fixed tilt system located in Sarnia, Ontario; tilt 25 degrees; spacing between arrays - 4m
  • With agriculture underneat the panels, more light is reflected - hence, reduced panel temperatures (according to one study 0.09oC/10% increase in reflection
  • Shading and radiation simulations are used to ascertain the min. height of panels convenient for crop growth
  • CFD model used to estimate the results
  • Root mean square error for temperature estimate - 1.91oC; Coefficient of determination - 0.98

Results

  • Compared with PV panel temperature at 0.5m for a normal PV site, 10oC temperature reduction can be achieved for PV panel installed at 4m above ground with crops (soybeans) underneath
  • Lower reflection - higher PV temperature as higher amounts of radiation absorbed in the ground and emitted as sensible heat; the cooling effect with higher reflection values is more prominent for cases without evapotranspiration than with evapotranspiration
  • In case of agricultural cover underneath - water particles (evaporated) may absorb reflected radiation; resulting in cooling of PVs - the cooling effect though is reduced with increased reflection values
  • In case of low albedo, the PV panel height has greater effect on PV panel's cooling as more radiation is emitted as heat - as albedo decreases, cooling effect increases with increased panel height
  • Increasing panel height to perform passive cooling is dependent of site conditions as well
  • Overall, PV panel temperature reduces as panel heights, reflectiviton is increased with inclusion of evapotranspiration

Economic Efficiency of Climate Smart Agriculture Technology: Case of Agrophotovoltaics[edit | edit source]

Mo, T.; Lee, H.; Oh, S.; Lee, H.; Kim, B.H.S. Economic Efficiency of Climate Smart Agriculture Technology: Case of Agrophotovoltaics. Land 2023, 12, 90, doi:10.3390/land12010090.

  • Generalized least square (GLS) used to ascertain profitability of AV
  • Generalized method of moments (GMM) used tp ascertain productivity of farm
  • AV installation is economically beneficial than not installing
  • AV is more beneficial in areas of low agricultural productivity
  • Crop productivity and AV profitability have inverse trend
  • AV more suited to be adopted by farmers of low-productivity agricultural land
  • Government should support small-scale farmers - especially financially

Designing Plant Transparent PV[edit | edit source]

Stallknecht, E.J.; Herrera, C.K.; Yang, C.; King, I.; Sharkey, T.D.; Lunt, R.R.; Runkle, E.S. Designing Plant–Transparent Agrivoltaics. Sci Rep 2023, 13, 1903, doi:10.1038/s41598-023-28484-5.

  • Each waveband within the PAR spectrum impact plant growth/morphology
  • Green light spectrum better at penetrating in the regions of plant which are shaded
  • Crops: herb basil, petunia and tomato investigated
  • Basil: Yield increases as daily light integral (DLI) was in between 6 to 12 mol/m2-day; not much impact when DLI increased above 12
  • Petunia: Yield increases as daily light integral (DLI) was in between 6 to 12 mol/m2-day; not much impact when DLI increased above 12
  • Tomato: Tomato yield increased linearly with DLI - any reduction alleviates tomato yield
  • One study indicated 25% shading can be tolerated by crops; upto 40% shading can be helpful in spring/summer while DLI's reduction during early springs/winters may be deterimental
  • Semi-transparent PVs shall be designed to absorb blue and green spectrum (more electrical output) than redu and far red spectrum (enhanced yield) - crops: lettuce, kale, geranium and snapdragon
  • Reduced DLI incrases stem length for tomato and decrease stem radii for basil and tomato
  • Crop quality was impacted anyhow with reduced DLI

Integrating Agrivoltaic Systems into Local Industries: A Case Study and Economic Analysis of Rural Japan[edit | edit source]

Nakata, H.; Ogata, S. Integrating Agrivoltaic Systems into Local Industries: A Case Study and Economic Analysis of Rural Japan. Agronomy 2023, 13, 513, doi:10.3390/agronomy13020513.

  • Objective: To ensure AV configuration bodes well within the community and minimizes adverse/undesirable implications
  • Location: Ine, Japan; core industry: Fisheries; crop: soybeans (as it is used as a feed to fishes)
  • For the research, problems associated with AV include safety, implications on local economy as well as contrasting output of agriculture and electricity
  • To ensure sustainable development, the model system considered the following
    • Safety of solar panel installation for AVs ensured by following recommended practices/standards
    • Land use condition included only reduction of agricultural output by 20% from reference yield
    • AV systems to imporve economic condition of the region through financial gains, employment, industrialization
  • The model shall further comply the following
    • AV to be installed on abandoned agricultural areas
      • Advantage - yield reduction to 20% limitation is not applicable
    • Land Area Occupation Ratio (LAOR) to be kept at or below 35%; allows crop rotations but reduces electrical output
    • Plants aiding food production and supplied to local industries to be employed
  • Identifying Abandoned Agricultural Land
    • Literature suggested only 1 ha or less
    • Interviews and surveys conducted
    • GIS technique used to estimate abandoned farmland
    • Total found out to be 52.9 ha
  • Electrical output for a single year is determined with varying LAOR
  • Agricultural production for soybean was esitmated for the same piece of land used for further processing
  • Based on the agricultural output, increased aquaculture production was estimated
  • For economic estimation
    • Sales of electricity, soybeans, soybean oil, soybean oil cake, aquaculture feed, and farmed fish (yellowtail) were defined as sales generated by AVS projects
  • Three different scenarios considered for CAPEX of the project (50kWac)
  • OPEX of the project also calcuated for one year
  • Area focused in the research has electrical potential of92% compared to the area's annual requirement, financial output of 108.9% compared to the location's gross regional product, 69.4% reduction in GHG emissions
  • Levelized Cost of Electricity (LCOE): 14.94 - 25.45 euro cents/kWh - high due to low electricity output and high CAPEX
  • Ripple effect of AV on local industries also esimtated
  • Interviews suggest better acceptance of AV on abandoned farmland

A sustainable development pattern integrating data centers and pasture-based agrivoltaic systems for ecologically fragile areas[edit | edit source]

Zhang, J.; Wang, T.; Chang, Y.; Liu, B. A Sustainable Development Pattern Integrating Data Centers and Pasture-Based Agrivoltaic Systems for Ecologically Fragile Areas. Resources, Conservation and Recycling 2023, 188, 106684, doi:10.1016/j.resconrec.2022.106684.

  • Objective: To come up with a system tying up data centers (DCs) and sustainable electricity through pasture-based photovoltaics (PPV) and understand its viability
  • Data centers are huge consumers of electricity; increase electricity requirements
  • Location: Qinghai Bigdata Industrial Park
  • Electrical production model is dependent on the required energy and atmospheric conditions - installation capacity and required area is ascertained
  • Study determined the electrical demand of DCs, electrical output from photovoltaic panels, decreased GHGs due to offset of electricity from PV and C stock enhancement as barren land is transformed to grassland
    • Power requirement for DCs - 5.046e7 kWh per year
    • PPV capacity - 1.363 e7 kWH per year
    • GHG reduced - 10965.4 tCO2 equivalent (dependent on power usage effectiveness (PUE))
  • Cost benefit analysis (CBA) is performed for socio-commercial assessment - Input-output method used
  • Environmental impact is mainfested from the GHGs reduction
  • Promising results for PPV and DC integration observed - from the base model, other provinces studies as well

Spectral-splitting concentrator agrivoltaics for higher hybrid solar energy conversion efficiency[edit | edit source]

Zhang, Z.; Zhang, F.; Zhang, W.; Li, M.; Liu, W.; Ali Abaker Omer, A.; Zheng, J.; Zhang, X.; Liu, W. Spectral-Splitting Concentrator Agrivoltaics for Higher Hybrid Solar Energy Conversion Efficiency. Energy Conversion and Management 2023, 276, 116567, doi:10.1016/j.enconman.2022.116567.

  • Spectral-splitting concentrator agrivoltaics (SCAPV) used for selective wavelength transmission for crop cultivation and absorptance for electrical output
  • PV cell efficiency - highest 26.7 %; photosynthetic efficiency 4.6% for C3 and 6% for C4 plants
  • Blue, red and far-red light used by plants; even excess radiation within PAR is radiated out and dissipated as heat
    • a-Si - not easy to control transmission;
    • organic photovoltaics (OPVs) - narrow spectrum range transmission (PAR passes through while only UV/IR used for electricity generation), transmission less than 10-20%
    • dye sensitized solar cells (DSSC) - use dye sensitizers for absorption; provides less flexibility, however, high transparency
    • perovskite cells (PVSCs) - high transparency, low absorptance, manufactured through element control tuning the band gap
  • Reduced heat removal from the crop and photoinhibition; shows excessive radiation not taking part in photosynthesis can be used
  • Preparation of SCAPV is done using two poylmers with different properties (refractive indices) allowing spectral transmission - multilayer polymer film (MPF)
    • MPF - transmission 87% between wavelength range of 397 nm to 493 nm and 604 nm to 852 nmPlant yield increased 13% and heat dissipation 50%
  • Parabolic trough concentrator (PTC) of SCAPV - dual axis tracking system used; 6.1m inter-row distance
  • Efficiency of SCAPV is esimated through calculations and practically through measurements; microclimate measurements are also performed
  • 65% transparency achieved in the wavelength range from 400 - 800nm
  • Photons not taking part in photosynthesis (green light and IR) is reflected

Results

  • Due to spectrum selective transmission results in PCE (power conversion efficiency) of 9.9% - experimentally through I-V curves
  • Efficiency of split sunlight versys complete sunlight is 54% for a silicon cells - normal PV efficiency was 22.5% from supplier; PV efficiency estimated to be 10.35%
  • Levelized cost of energy (LCOE) of $0.033/kWh; yearly electricity generation 80 kWh/m2 despite SCAPV operating mainly on direct irradiation
  • Biomass increased by 13% - crops: potato and lettuce;
  • Nonphotochemical Quenching (NPQ) - used as a measure for heat dissipation; under SCAPV NPQ reduces while under normal setting (without SCAPV) higher NPQ observed
  • Air and soil temperature under SCAPV were lower; soil-water nexus improved
  • Combined efficiency - conversion of solar energy into biomass 39% higher than normal sunlight

Techno‑economic analysis of PV systems installed by using innovative strategies for smart sustainable agriculture farms[edit | edit source]

Aziz, Y.; Janjua, A.K.; Hassan, M.; Anwar, M.; Kanwal, S.; Yousif, M. Techno-Economic Analysis of PV Systems Installed by Using Innovative Strategies for Smart Sustainable Agriculture Farms. Environ Dev Sustain 2023, doi:10.1007/s10668-023-02919-5.

  • Feasibilty study performed for different cities in Pakistan to install solar PV system for agricultural farms
  • 14.5 kW (small-scale) and 145 kW (large-scale) PV system established
  • Technical, financial and environmental implications studies for farmlands - positive impact in all faucets

Agrivoltaics: The Environmental Impacts of Combining Food Crop Cultivation and Solar Energy Generation[edit | edit source]

Wagner, M.; Lask, J.; Kiesel, A.; Lewandowski, I.; Weselek, A.; Högy, P.; Trommsdorff, M.; Schnaiker, M.-A.; Bauerle, A. Agrivoltaics: The Environmental Impacts of Combining Food Crop Cultivation and Solar Energy Generation. Agronomy 2023, 13, 299, doi:10.3390/agronomy13020299.

  • To ascertain environmental impacts of converting farmland to AV using Consequential Life-Cycle Assessment (CLCA)
  • Closed AV - refers to greenhouse; Open AV divided in to two categories - overhead (modules mounted as highg as 2 to 7m) and interspace
  • 2% of the area is used for PV installation ibn AV configuration - less area remains for cultivation
  • 1 hectare farm is converted to overhead AV configuration for enivronmental assessment
  • 16 impacts categories used based on Product Environmental Footprint methodology
  • software openLCA 1.10.3 used for modelling and impact calculation
  • 0.15 additional land is required to compensate for the loss in agricultural production - chiefly due to shading and area loss
  • Loss of arable restricted to 10% and agricultural output reduction to 34% in Germany for AV to qualify

Results

  • Environmental impact categories - 15 out 16 showed positive influence (climate change, fossil resource use etc.)
  • Alleviated 572.94t CO2-eq due to conversion of 1 ha land
  • Fossil energy reduction - 6745 GJ
  • Only negative impact is the resource use, minerals and metals - due to production of PV and balance of system (BOS)

Worldwide Research Trends in Agrivoltaic Systems—A Bibliometric Review[edit | edit source]

Chalgynbayeva, A.; Gabnai, Z.; Lengyel, P.; Pestisha, A.; Bai, A. Worldwide Research Trends in Agrivoltaic Systems—A Bibliometric Review. Energies 2023, 16, 611, doi:10.3390/en16020611.

  • Bibliometric analysis carried out using SCOPUS
  • 121 articles reviewed in total after screening
  • Major research performed in last three years - mostly in US and China
  • Yield reductions of 20% observed in few studies, while some showed increase in yield under hot climates
  • One study indicated that almost 70% of sheep grazing was performed under shades of PV in AV configuration when irradiance was 800 W/m2 or more - same study showed 5.19 MWh of annual electrical production, 2.77 tons of GHG emission reduction and economic advantage of 740$ annually
  • CO2 emission reduction potential of AV is between 20-55%
  • Economic value of traditional agriculture increases by 30% when AV is employed
  • With transparency of 68% and no adverse implications on agriculture, AV can produce 200 kWh/m2 of energy
  • LCOE of AV found out to be 38% higher when compared with GM-PV (Groun-mounted Photovoltaics) due to high intial capital investiment; in Germany CAPEX was 73% higher
  • OPEX reduction for AV is 13% when comapred with conventional PV
  • IRR was greater than 8% for AV with 20% yield reduction
  • Global land productivity can be increased between 35% to 73% by employing AV
  • More research required on economics of AV
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