Design considerations for a solar-powered desalination system for remote communities in Australia[edit | edit source]
[12]B. S. Richards and A. I. Schäfer, "Design considerations for a solar-powered desalination system for remote communities in Australia," Desalination, vol. 144, no. 1–3, pp. 193–199, Sep. 2002.
Water in many areas of Australia is scarce and of poor quality. In some areas high levels of treatment are required either due to contamination of waters or due to high salinity. Nanofiltration (NF) and low-pressure reverse osmosis membranes are well-recognized technologies to treat waters of qualities ranging from low salinity surface water to high salinity seawater. In remote communities the operation of such facilities may be limited by the availability of electricity. Solar, or photovoltaic, energy is the ideal source of renewable energy in Australia to overcome this problem. This paper considers the various options for a small system, designed to deliver a permeate flow of 400–1000 l/d from brackish wells. The most suitable membrane for salt retention and very high organics retention was selected and the pump energy requirements calculated. A submerged ultrafiltration (UF) membrane is used as an alternative to the traditional sand and/or prefilter cartridges. The removal of natural organics is important where disinfection of the water is required, as chlorination of waters containing natural organics may produce potentially carcinogenic by-products.
Notes:
- modularity advantage of PV notable
- BP Solar 85W Si solar cells, 15.5% energy conversion efficiency
- crystalline Si- performance decreases to 13.3% when at proposed operating temp of 60 degrees C
- battery disadvantages- short lifetime (5-8 yrs), require maintenance, increased costs, 20% losses in current to and from battery system
- battery advantages- ability to run system at night (large battery bank probably needed)
- for recyclebot purposes, batteries may not be needed (aiming for running time of around 4-8 hrs)
- solar tracker increases water pumped by 30%, but increased cost and maintenance due to need for mechanical parts + control systems
- electronic charge controller necessary
Photovoltaic-powered desalination system for remote Australian communities[edit | edit source]
[13]B. S. Richards and A. I. Schäfer, "Photovoltaic-powered desalination system for remote Australian communities," Renewable Energy, vol. 28, no. 13, pp. 2013–2022, Oct. 2003.
This paper reports on the design and successful field testing of a photovoltaic (PV)-powered desalination system. The system described here is intended for use in remote areas of the Australian outback, where fresh water is extremely limited and it is often necessary to drink high salinity bore water. A hybrid membrane configuration is implemented, whereby an ultrafiltration (UF) module is used for removing particulates, bacteria and viruses, while a reverse osmosis (RO) or nanofiltration (NF) membrane retains the salts. The concepts of water and energy recovery are implemented in the design. Field trials, performed in White Cliffs (New South Wales), demonstrated that clean drinking water was able to be produced from a variety of feed waters, including high salinity (3500 mg/l) bore water and high turbidity (200 NTU) dam water. The specific energy consumption ranged from 2 to 8 kW h/m3 of disinfected and desalinated drinking water, depending on the salinity of the feed water and the system operating conditions. The optimum operating pressure when filtering bore water was determined to be in the range 6–7 bar.
Notes:
- successful field testing of previously proposed PV powered desalination system (see [12])
- total power draw of 150W from pumps
- optimized to run without batteries due to battery disadvantages- electrical losses, increased maintenance, strong chemical usage, problems with battery recycling in developing countries
- direct relation between power consumption and system pressure
- 3 85W PV panels-excess power availability (could be optimized)
Small-scale photovoltaic-powered reverse osmosis plant without batteries: Design and simulation[edit | edit source]
[14]D. B. Riffel and P. C. M. Carvalho, "Small-scale photovoltaic-powered reverse osmosis plant without batteries: Design and simulation," Desalination, vol. 247, no. 1–3, pp. 378–389, Oct. 2009.
A small-scale photovoltaic (PV) powered reverse osmosis (RO) plant is designed to operate at variable flow/pressure conditions for stand-alone applications in equatorial areas to desalinate brackish water. Two operation strategies for a PV array of 165 Wp (3 modules of 55 Wp) are simulated and compared: Plant 1 uses two modules for the RO pump and one module for the well pumping; Plant 2 uses the three modules for both applications. A DC–DC buck converter with maximum power point tracking (MPPT) was developed especially for Plant 2. Results show that Plant 2 has a better performance, such as: increase of 60% in the daily permeate production and of 32% in the daily operation period, 1.57 kWh.m−3 of average specific energy consumption and a PV power-permeate daily production rate of 0.64 Wp.L−1 for a feed water with 800 mg.L−1 of total dissolved solid.
Notes:
- PV array-3 55W modules were simulated
- dc-dc buck converter and MPPT
- without batteries, variations in operation expected-problem for recyclebot or just for mechanical pumps?
- two array configurations-1. 2 modules RO, 1 module well pump 2. 3 modules for both together
- for PV arrays, max point on I-V characteristic: max power point
- control algorithm to maintain array at best fixed voltage
- master-slave config w/o microcontrollers
- config 2-60% greater production than config 1
Design optimization of photovoltaic powered water pumping systems[edit | edit source]
[15]A. A. Ghoneim, "Design optimization of photovoltaic powered water pumping systems," Energy Conversion and Management, vol. 47, no. 11–12, pp. 1449–1463, Jul. 2006.
The use of photovoltaics as the power source for pumping water is one of the most promising areas in photovoltaic applications. With the increased use of water pumping systems, more attention has been paid to their design and optimum utilization in order to achieve the most reliable and economical operation. This paper presents the results of performance optimization of a photovoltaic powered water pumping system in the Kuwait climate. The direct coupled photovoltaic water pumping system studied consists of the PV array, DC motor, centrifugal pump, a storage tank that serves a similar purpose to battery storage and a maximum power point tracker to improve the efficiency of the system. The pumped water is desired to satisfy the domestic needs of 300 persons in a remote area in Kuwait. Assuming a figure of 40 l/person/day for water consumption, a volume of 12 m3 should be pumped daily from a deep well throughout the year.
A computer simulation program is developed to determine the performance of the proposed system in the Kuwait climate. The simulation program consists of a component model for the PV array with maximum power point tracker and component models for both the DC motor and the centrifugal pump. The five parameter model is adapted to simulate the performance of amorphous silicon solar cell modules. The size of the PV array, PV array orientation and the pump–motor–hydraulic system characteristics are varied to achieve the optimum performance for the proposed system.
The life cycle cost method is implemented to evaluate the economic feasibility of the optimized photovoltaic powered water pumping system. At the current prices of PV modules, the cost of the proposed photovoltaic powered water pumping system is found to be less expensive than the cost of the conventional fuel system. In addition, the expected reduction in the prices of photovoltaic modules in the near future will make photovoltaic powered water pumping systems more feasible.
Notes:
- radiation threshold-level of radiation at which pump will start operating
- four parameters model does not take into account shunt resistance, important for a-Si -> five parameters model for simulating a-Si PV cells
An improved MPPT converter with current compensation method for small scaled PV-applications[edit | edit source]
[16]H.-J. Noh, D.-Y. Lee, and D. Hyun, "An improved MPPT converter with current compensation method for small scaled PV-applications," in IECON 02 [Industrial Electronics Society, IEEE 2002 28th Annual Conference of the], 2002, vol. 2, pp. 1113–1118 vol.2.
An improved MPPT converter with current compensation method for small-scaled PV-applications is presented in this paper. The proposed method implements maximum power point tracking (MPPT) by variable reference current which is continuously changed during one sampling period. Therefore, the proposed MPPT converter with current compensation method increases the power transferred to the load above 9%. As a result, the utilization efficiency of the photovoltaic (PV)-module can be increased. In addition, as it doesn't use a digital signal processor (DSP), this MPPT method has the merits of both being cost efficient and having a simple control circuit design. Therefore, it is considered that the proposed MPPT method is proper to use for low power, low cost PV-applications. The concept and control principles of this improved MPPT method are explained in detail and the validity of the proposed method is verified through several simulated results.
Notes:
- output power increased 9% compared to conventional mppt method
- simple control circuit- best for low-cost applications
A review of solar photovoltaic technologies[edit | edit source]
[17]B. Parida, S. Iniyan, and R. Goic, "A review of solar photovoltaic technologies," Renewable and Sustainable Energy Reviews, vol. 15, no. 3, pp. 1625–1636, Apr. 2011.
Global environmental concerns and the escalating demand for energy, coupled with steady progress in renewable energy technologies, are opening up new opportunities for utilization of renewable energy resources. Solar energy is the most abundant, inexhaustible and clean of all the renewable energy resources till date. The power from sun intercepted by the earth is about 1.8 × 1011 MW, which is many times larger than the present rate of all the energy consumption. Photovoltaic technology is one of the finest ways to harness the solar power. This paper reviews the photovoltaic technology, its power generating capability, the different existing light absorbing materials used, its environmental aspect coupled with a variety of its applications. The different existing performance and reliability evaluation models, sizing and control, grid connection and distribution have also been discussed.
Notes:
- c-Si improved efficiency over a-Si (14-19%)
- thin film PV- c-Si cells with efficiencies >19%
- paper touches on multiple aspects of PV technologies, useful reading for an intro to PV
A fast maximum power point tracker for photovoltaic power systems[edit | edit source]
[18]C.-T. Pan, J.-Y. Chen, C.-P. Chu, and Y.-S. Huang, "A fast maximum power point tracker for photovoltaic power systems," in The 25th Annual Conference of the IEEE Industrial Electronics Society, 1999. IECON '99 Proceedings, 1999, vol. 1, pp. 390–393 vol.1.
In this paper, the authors proposed a novel maximum power point controller, which not only can track the maximum power of an array quickly without perturbation and observation process but also can be implemented easily. The main idea is based on the graphical interpretation of the maximum power point as the intersecting point of two curves on the phase plane corresponding to the solution of two algebraic equations. In other words, the operating point is the intersecting point of the PV-array characteristic curve and the maximum power line. A circuit is constructed based on a boost circuit and a three phase full bridge inverter
Notes:
- extremely simply analog MPPT controller circuit- might be better/cheaper than trying to implement a microcontroller
- this is an older paper
Optimization of perturb and observe maximum power point tracking method[edit | edit source]
[19]N. Femia, G. Petrone, G. Spagnuolo, and M. Vitelli, "Optimization of perturb and observe maximum power point tracking method," IEEE Transactions on Power Electronics, vol. 20, no. 4, pp. 963–973, Jul. 2005.
Maximum power point tracking (MPPT) techniques are used in photovoltaic (PV) systems to maximize the PV array output power by tracking continuously the maximum power point (MPP) which depends on panels temperature and on irradiance conditions. The issue of MPPT has been addressed in different ways in the literature but, especially for low-cost implementations, the perturb and observe (P&O) maximum power point tracking algorithm is the most commonly used method due to its ease of implementation. A drawback of P&O is that, at steady state, the operating point oscillates around the MPP giving rise to the waste of some amount of available energy; moreover, it is well known that the P&O algorithm can be confused during those time intervals characterized by rapidly changing atmospheric conditions. In this paper it is shown that, in order to limit the negative effects associated to the above drawbacks, the P&O MPPT parameters must be customized to the dynamic behavior of the specific converter adopted. A theoretical analysis allowing the optimal choice of such parameters is also carried out. Results of experimental measurements are in agreement with the predictions of theoretical analysis.
Notes:
- "perturb and observe" MPPT is most common for low-cost applications
- if V is perturbed in a direction that such that the power increases, the system has moved toward MPP
- obvious drawback- perturbation leads to momentary decreases in power while oscillating around MPP
- no general agreement in literature of whether P+O or incremental conductance is best
A Maximum Power Point Tracking System With Parallel Connection for PV Stand-Alone Applications[edit | edit source]
[20]R. Gules, J. De Pellegrin Pacheco, H. L. Hey, and J. Imhoff, "A Maximum Power Point Tracking System With Parallel Connection for PV Stand-Alone Applications," IEEE Transactions on Industrial Electronics, vol. 55, no. 7, pp. 2674–2683, Jul. 2008.
This paper presents the analysis, design, and implementation of a parallel connected maximum power point tracking (MPPT) system for stand-alone photovoltaic power generation. The parallel connection of the MPPT system reduces the negative influence of power converter losses in the overall efficiency because only a part of the generated power is processed by the MPPT system. Furthermore, all control algorithms used in the classical series-connected MPPT can be applied to the parallel system. A simple bidirectional dc-dc power converter is proposed for the MPPT implementation and presents the functions of battery charger and step-up converter. The operation characteristics of the proposed circuit are analyzed with the implementation of a prototype in a practical application.
Notes:
- parallel connection of converter instead of series- reduces losses due to converter efficiency
- classic MPPT algorithms may struggle with series connected modules due to multiple MPPs
Reliability Issues in Photovoltaic Power Processing Systems[edit | edit source]
[21]G. Petrone, G. Spagnuolo, R. Teodorescu, M. Veerachary, and M. Vitelli, "Reliability Issues in Photovoltaic Power Processing Systems," IEEE Transactions on Industrial Electronics, vol. 55, no. 7, pp. 2569–2580, Jul. 2008.
Power processing systems will be a key factor of future photovoltaic (PV) applications. They will play a central role in transferring, to the load and/or to the grid, the electric power produced by the high-efficiency PV cells of the next generation. In order to come up the expectations related to the use of solar energy for producing electrical energy, such systems must ensure high efficiency, modularity, and, particularly, high reliability. The goal of this paper is to provide an overview of the open problems related to PV power processing systems and to focus the attention of researchers and industries on present and future challenges in this field.
Notes:
- inverter often most vulnerable component
- inverters- avoidance of electrolytic capacitors assumed to increase reliability
- MOSFETs often fail due to temperature
- factors for reliability: converter/inverter design, control systems, climatic conditions
- analog MPPT schemes cheaper but less reliable than digital and inflexible (new circuitry needed for any changes)
- losses from shading up to 70% due to MPPT algorithm inability to locate absolute MPP - decentralized modular structure to combat this
Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques[edit | edit source]
[22]T. Esram and P. L. Chapman, "Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques," IEEE Transactions on Energy Conversion, vol. 22, no. 2, pp. 439–449, Jun. 2007.
The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed. The techniques are taken from the literature dating back to the earliest methods. It is shown that at least 19 distinct methods have been introduced in the literature, with many variations on implementation. This paper should serve as a convenient reference for future work in PV power generation.
Notes:
- hill climbing and perturb+observe methods can fail under rapidly changing atmospheric conditions
- incremental conductance - comparing instantaneous conductance to incremental conductance
- ripple correlation control - correlates dp/dt with di/dt to reach MPP
- load current/voltage maximization - load current used as control variable, positive feedback used to control power converter such that load current is maximized (assumes converter is lossless, rarely actually reaches MPP)
- dp/dv or dp/di control - use microcontroller to compute derivative and drive it to zero
Life cycle analysis of distributed recycling of post-consumer high density polyethylene for 3-D printing filament[edit | edit source]
[23]M. A. Kreiger, M. L. Mulder, A. G. Glover, and J. M. Pearce, "Life cycle analysis of distributed recycling of post-consumer high density polyethylene for 3-D printing filament," Journal of Cleaner Production, vol. 70, pp. 90–96, May 2014.
The growth of desktop 3-D printers is driving an interest in recycled 3-D printer filament to reduce costs of distributed production. Life cycle analysis studies were performed on the recycling of high density polyethylene into filament suitable for additive layer manufacturing with 3-D printers. The conventional centralized recycling system for high population density and low population density rural locations was compared to the proposed in home, distributed recycling system. This system would involve shredding and then producing filament with an open-source plastic extruder from post-consumer plastics and then printing the extruded filament into usable, value-added parts and products with 3-D printers such as the open-source self replicating rapid prototyper, or RepRap. The embodied energy and carbon dioxide emissions were calculated for high density polyethylene recycling using SimaPro 7.2 and the database EcoInvent v2.0. The results showed that distributed recycling uses less embodied energy than the best-case scenario used for centralized recycling. For centralized recycling in a low-density population case study involving substantial embodied energy use for transportation and collection these savings for distributed recycling were found to extend to over 80%. If the distributed process is applied to the U.S. high density polyethylene currently recycled, more than 100 million MJ of energy could be conserved per annum along with the concomitant significant reductions in greenhouse gas emissions. It is concluded that with the open-source 3-D printing network expanding rapidly the potential for widespread adoption of in-home recycling of post-consumer plastic represents a novel path to a future of distributed manufacturing appropriate for both the developed and developing world with lower environmental impacts than the current system.
Notes:
- Other "recyclebots": Lyman Filament Extruder, Perpetual Plastic Project, Filabot, MiniRecycleBot
- for recyclebot: 2.5 MJ/kg compared to 79.67 MJ/kg for virgin HDPE feedstock
- using PV for distributed recycling drastically reduces emissions from HDPE filament fab.
- distributed recycling reduces embodied energy 69-82% for low density pop. areas
- best case scenario: on-site recycling with recyclebot
Photovoltaic projects for decentralized power supply in India: A financial evaluation[edit | edit source]
[24]M. R. Nouni, S. C. Mullick, and T. C. Kandpal, "Photovoltaic projects for decentralized power supply in India: A financial evaluation," Energy Policy, vol. 34, no. 18, pp. 3727–3738, Dec. 2006.
The present study concentrates on photovoltaic (PV) projects for providing decentralized power supply in remote locations in India. Results of a techno-economic evaluation are presented. Some PV projects in the capacity range 1–110 kWp, that have either been implemented or are under implementation, have been considered. An analysis of the capital cost of the PV projects and sub-systems has been undertaken. Levelized unit cost of electricity (LUCE) has been estimated for eighteen select locations situated in different geographical regions of the country. The LUCE is found to vary in the range of Rs. 28.31–59.16/kW h (US$ 0.65–1.35/k Wh) for PV projects in the capacity range 1–25 kWp. In view of high unit cost of electricity from PV projects, need for financial incentives has been examined from the perspective of users. A sensitivity analysis has also been undertaken.
Notes:
- systems considered are standard PV arrays with usual power electronics for off-grid rural electrification
Assessment and evaluation of PV based decentralized rural electrification: An overview[edit | edit source]
[25]A. Chaurey and T. C. Kandpal, "Assessment and evaluation of PV based decentralized rural electrification: An overview," Renewable and Sustainable Energy Reviews, vol. 14, no. 8, pp. 2266–2278, Oct. 2010.
The challenges of providing electricity to rural households are manifold. Ever increasing demand–supply gap, crumbling electricity transmission and distribution infrastructure, high cost of delivered electricity are a few of these. Use of renewable energy technologies for meeting basic energy needs of rural communities has been promoted by the Governments world over for many decades. Photovoltaic (PV) technology is one of the first among several renewable energy technologies that was adopted globally as well as in India for meeting basic electricity needs of rural areas that are not connected to the grid. This paper attempts at reviewing and analyzing PV literature pertaining to decentralized rural electrification into two main categories—(1) experiences from rural electrification and technology demonstration programmes covering barriers and challenges in marketing and dissemination; institutional and financing approaches; and productive and economic applications, (2) techno-economic aspects including system design methodologies and approaches; performance evaluation and monitoring; techno-economic comparison of various systems; and environmental implications and life cycle analysis. The paper discusses the emerging trends in its concluding remarks.
Notes:
- (citing another paper) maintenance of PV systems by user rarely successful, technical assistance should be easily accessible
- multiple papers cite the failure of inverters as a weakness perceived by users of distributed PV systems
- selection of reliable and easily replaceable components may be important, lead to more satisfied users
- success of PV system implementation and economic effectiveness varies based on regions and countries, hard to generalize
Implementation of a stand-alone photovoltaic system based on decentralized dc-dc converters[edit | edit source]
[26]D. B. Candido, J. R. R. Zientarski, R. C. Beltrame, J. R. Pinheiro, and H. L. Hey, "Implementation of a stand-alone photovoltaic system based on decentralized dc-dc converters," in Power Electronics Conference, 2009. COBEP '09. Brazilian, 2009, pp. 174–180.
This paper presents an alternative for standalone PV systems that performs a decentralized input energy processing with maximum power point tracking and a bidirectional converter to manage the power flux control of the battery bank. Previous works demonstrate that the gain in efficiency can reach up to 16% in situations where one or more photovoltaic panels are shaded, damaged or aged. Simulation analyses and experimental results are provided to demonstrate the prospects of the proposed system.
Notes:
- batteries can represent up to 15% of initial costs for PV system (46% when maintenance considered)
- multiple battery charging methods and modes of operation explored through simulation
- P+O MPPT algorithm
- current controlled battery charging best option (maximizes battery lifetime)
Performance of a directly-coupled PV water pumping system[edit | edit source]
[27]A. Mokeddem, A. Midoun, D. Kadri, S. Hiadsi, and I. A. Raja, "Performance of a directly-coupled PV water pumping system," Energy Conversion and Management, vol. 52, no. 10, pp. 3089–3095, Sep. 2011.
This paper describes the experimental study carried out to investigate the performance of a simple, directly coupled dc photovoltaic (PV) powered water pumping system. The system comprises of a 1.5 kWp PV array, dc motor and a centrifugal pump. The experiment was conducted over a period of 4 months and the system performance was monitored under different climatic conditions and varying solar irradiance with two static head configurations. Although the motor–pump efficiency did not exceed 30%, which is typical for directly-coupled photovoltaic pumping systems, such a system is clearly suitable for low head irrigation in the remote areas, not connected to the national grid and where access to water comes as first priority issue than access to technology. The system operates without battery and complex electronic control, therefore not only the initial cost is low but also maintenance, repairing and replacement cost can be saved. The study showed that directly coupled system attains steady state soon after any abrupt change.
Notes:
- 30 PV modules (2 series strings connected in parallel), motor-pump assembly, water storage tanks
- simplification of system leads to low cost, high reliability
- all components except PV modules locally-sourced (Algeria)
- diode protection against reverse current flow, no control electronics
- 4 month data collection, system is suitable for low delivery flow applications
Photovoltaic-powered rural zone family house in Egypt[edit | edit source]
[28]G. E. Ahmad, "Photovoltaic-powered rural zone family house in Egypt," Renewable Energy, vol. 26, no. 3, pp. 379–390, Jul. 2002.
In the development of energy sources in rural regions in Egypt at the brink of the 21st century, it is necessary to view the use of solar energy in all applications as one of the most promising new and renewable energy sources. This paper presents a study and design of a complete photovoltaic system for providing the electrical loads in a family house according to their energy requirements. A computer program is developed to achieve this and to determine the specifications of photovoltaic (PV) system components. It uses the solar energy data of the selected rural zone and all the required information about the electrical loads. Also, the effects of solar intensity variations and surface temperature variations on the amount of power provided by the PV panels are taken into consideration. It is found that providing electricity to a family house in a rural zone using PV systems is very beneficial and competitive with the other types of conventional energy sources, especially considering the decreasing prices of these systems and their increasing efficiencies and reliability. They have also the advantage of maintaining a clean environment.
Notes:
- design considerations for a PV-powered rural household in Egypt were explored by analyzing climatic data, estimated energy requirements, estimated irradiation, electronic power efficiencies, and economics
Photovoltaic powered water purification — challenges and opportunities[edit | edit source]
[29]M. Forstmeier, W. Feichter, and O. Mayer, "Photovoltaic powered water purification — challenges and opportunities," Desalination, vol. 221, no. 1–3, pp. 23–28, Mar. 2008.
One third of the world population does not have access to clean water sources and most of these people are not connected to the electrical grid at the same time. Therefore, photovoltaic (PV) powered water purification suggests itself to be one of the solutions in areas with high sun radiation like India or the MENA (Middle East and North Africa) region. Furthermore, the environmental impact of the process can be reduced substantially as no fuel supply is required.
The paper presents a concept of combining a membrane filtration plant with PV power supply only. As PV is a fluctuating energy source and the conventional membrane process needs a constant power input to maintain pressure and flow on the membranes to guarantee their lifetime, some challenges in the system design need to be addressed. Mere coupling of off-the-shelf components does not do the job.
A full-scale system for sustainable water purification has been designed and tested in the lab and a pilot location. The results are presented in the paper.
Beyond the environmental benefits, the system also competes with standard systems on the market. Based on the experimental results, a cost model has been derived, the main cost factors for the system will be established and a design strategy for a small-scale PV powered system, able to supply a farm or village with safe potable water, is presented.
Notes:
- batteries can level off power output for constant operation, but cut energy output by 30-50%, have limited lifetimes, require maintenance
- small-scale, off-grid PV-powered membrane water purification is feasible and economically competitive to non-local water sources
