PV powered universities literature review/Optimal 24-hr utilization of a PV solar system

Optimal 24-hr utilization of a PV solar system as STATCOM (PV-STATCOM) in a distribution network[1][1][1][1][1][14][14][edit | edit source]

Abstract This paper presents a novel optimal utilization of photovoltaic solar system as STATCOM for voltage regulation and power factor correction during both nighttime and daytime. The PV solar system conventionally generates real power during the day but the entire asset remains idle at night. This novel PV solar system operated as STATCOM is termed PV-STATCOM which utilizes the entire inverter capacity in the night and that remaining after real power generation during the day for accomplishing various STATCOM functionalities. Bluewater Power Corporation in Sarnia, Canada, is going to showcase this new concept of optimal utilization of PV solar system on a 10kW PV system in its network. The controller for the PV-STATCOM is being developed in the university lab and will be installed in the distribution utility network. A simulation model for the 10kW PV-STATCOM and the Bluewater Power distribution system network is developed in PSCAD software. This paper presents the steady state and transient performance of the PV-STATCOM controller for voltage regulation and power factor control both during nighttime and daytime. This proposed PV-STATCOM if connected at the terminals of an industrial customer having induction motor loads can help improve power factor and avoid potential penal tariffs over a 24-hour period, in addition to generating revenues due to sale of real power during the day.

• A PV solar system inverter can be used as a STATCOM for voltage control and power factor correction
• The simulation model for the controller can be built using PSCAD/EMTDC
• The inverter is controlled in current-control mode, using the hysteresis band modulation technique

Photovoltaic module shading: Smart Grid impacts[2][2][2][2][2][15][15][edit | edit source]

Abstract In the design of a solar photovoltaic system, one criterion that continues to receive low priority is the provision of minimum inter row spacing for photovoltaic modules. Consumers and installers alike strive to maximize area usage for systems such that they achieve the highest amount of annual energy output. This, in turn, leads to module rows being designed very close to each other; with array tilt lowered in an attempt to reduce inter row shading. This design practice fails to take into consideration many effects that close row spacing can have on system output. When designing a photovoltaic array to optimize its performance as a power generator and its contribution to the electric grid during peak demand periods - shading concerns become a key consideration. This paper describes a process developed at Rowan University's Center for Sustainable Design to test the impact that inter row shading can have on power output and performance across the day. A test rig and protocol were created which tested module's output given various depths of shading from one row of modules upon another. The exclusion of bypass diodes in the system was also tested to view the most extreme possible cases of power loss induced by shading. The results of this experimentation showed that even very small amounts of shading upon solar photovoltaic modules can lead to significant loss in power generation. As more PV systems are installed on the utility system their availability during peak times becomes an ever increasing requirement for Smart Grid success. This paper also explores the ramifications that proper inter row spacing design guidelines could have on reinforcing some of the fundamental principles of Smart Grid.

• A significant loss of power will occur even if a very small amount of shading exist upon solar photovoltaic modules
• Power output of modules can be maximized by optimization of the balance between maximum module density per area and minimum module shading
• Intermittent sources have a greater potential for availability during summer peaking utility's peak demand period
• By considering the altitude and azimuth angles of the sun at the design latitude and longitude, optimal row spacing can be determined
• Bypass diodes can be used in the PV modules in order to reduce the amount of power that is wasted in the shaded area
• Applying a bypass diode to each individual cell is not practical; therefore, the bypass diode is run in parallel to a series string of cells
• Efficiency of a photovoltaic module begins to drop above a certain temperature, and efficiency losses could not be negligible if the temperature goes above 40 degrees of Celsius

An innovative approach for determining PV cost convergence in the 25 Solar America Cities[3][3][3][3][3][16][16][edit | edit source]

Abstract This presentation introduces the PV cost convergence calculator (PV CCC) developed under a contract supporting the U.S. Department of Energy's (DOE) Solar America Cities (SAC) program. The PV CCC is the first tool of its kind to provide a means to compare solar PV levelized costs and the timing of PV cost convergence with conventional energy sources for inter-city residential and commercial systems. The model reveals the specific impacts of various types of incentives on grid parity, and provides valuable input for strategic planning activities.

• The PV CCC considers important regional information such as local energy prices, and local incentives, both of which vary widely throughout United States

Quantifying rooftop solar photovoltaic potential for regional renewable energy policy[4][4][4][4][4][17][17][edit | edit source]

Abstract Solar photovoltaic (PV) technology has matured to become a technically viable large-scale source of sustainable energy. Understanding the rooftop PV potential is critical for utility planning, accommodating grid capacity, deploying financing schemes and formulating future adaptive energy policies. This paper demonstrates techniques to merge the capabilities of geographic information systems and object-specific image recognition to determine the available rooftop area for PV deployment in an example large-scale region in south eastern Ontario. A five-step procedure has been developed for estimating total rooftop PV potential which involves geographical division of the region; sampling using the Feature Analyst extraction software; extrapolation using roof area-population relationships; reduction for shading, other uses and orientation; and conversion to power and energy outputs. Limitations faced in terms of the capabilities of the software and determining the appropriate fraction of roof area available are discussed. Because this aspect of the analysis uses an integral approach, PV potential will not be georeferenced, but rather presented as an agglomerate value for use in regional policy making. A relationship across the region was found between total roof area and population of 70.0 m2/capita ± 6.2%. With appropriate roof tops covered with commercial solar cells, the potential PV peak power output from the region considered is 5.74 GW (157% of the region's peak power demands) and the potential annual energy production is 6909 GWh (5% of Ontario's total annual demand). This suggests that 30% of Ontario's energy demand can be met with province-wide rooftop PV deployment. This new understanding of roof area distribution and potential PV outputs will guide energy policy formulation in Ontario and will inform future research in solar PV deployment and its geographical potential.

• For the analysis of available rooftop PV potential a five step process has been used including geographic division, sampling, extrapolation, reduction, and conversion
• Feature Analyst software has been used as an extension of ArcGIS for determining the rooftop areas
• Building orientation, shading and other uses of rooftops have been also taken into account in this study which has been done in the implementation step

Design and implementation of a 12 kW wind-solar distributed power and instrumentation system as an educational testbed for Electrical Engineering Technology students[5][5][5][5][5][18][18][edit | edit source]

Abstract The main objective of this paper is to report and present design and implementation of a 12 kW solar-wind hybrid power station and associated wireless sensors and LabView based monitoring instrumentation systems to provide a teaching and research facility on renewable energy areas for students and faculty members in Electrical Engineering Technology (EET) programs at the University of Northern Iowa (UNI). This new ongoing project requires to purchase a 10 kW Bergey Excel-S wind turbine with a Power Sink II utility intertie module (208 V/240V AC, 60 Hz), eight BP SX175B 175W solar PhotoVoltaic (PV) panels, and related power and instrumentation/data acquisition hardware. A 100 ft long wind tower to house the new wind turbine is available at UNI campus. Furthermore, the electricity generated by this power station will be used as a renewable energy input for a smart grid based green house educational demonstration project to aid the teaching and research on smart grid and energy efficiency issues. 330:038 Introduction to Electrical Power/Machinery, 330:166 Adv Electrical Power Systems, 330:059/159 Wind Energy Applications in Iowa, 330:059/159 (2) Solar Energy Applications and Issues, and 330:186 Wind Energy Management are the classes that will use this proposed testbed. There are also workshops planned for the area Science, Technology, Engineering, and Mathematics (STEM) teachers as well as local farmers' education and training on wind and solar power systems. Previous workshops organized by UNI Continuing and Distance Education have been very successful. The hybrid unit contains two complete generating plants, a wind-turbine system and a PV solar-cell plant. These sources are connected and synchronized in parallel to the UNI power grid as part of laboratory activities on wind-solar hybrid power systems and grid-tie interactions. The proposed project is part of a program initiative to improve our laboratory facilities to better reflect on the current and future renewab- - le energy technologies. The proposed testbed will allow students to be educated and trained in the utilization of real-time electrical power systems and additionally will allow them to gain valuable "hand-on" experience in setting up a real-time data acquisition system specifically in grid-tied wind-solar power systems. Since Iowa's solar energy resources are higher in summer, this will provide an excellent complement to the load demand when summers are not windy.

• The battery bank and diesel requirements is reduced by combining photovoltaic and wind in a hybrid energy system
• Batteries lose 1 to 5 percent of their energy content per hour; therefore, they can store energy only for a short period of time
• Various optimization techniques such as linear programming, dynamic programming and so on are used to design a hybrid system in a most cost effective way

Comparison of photovoltaic module performance at Pu'u Wa'a Wa'a[6][6][6][6][6][19][19][edit | edit source]

Abstract: Hawaii is experiencing a substantial increase in grid-tied PV installations and utility companies are concerned with the resulting grid management issues. To address these concerns and to enable the utilities to make informed decisions, the Hawaii Natural Energy Institute (HNEI) of the University of Hawaii initiated a PV test program that provides high-resolution data to characterize module and array performance under a variety of local climatic conditions. In the first phase of the project HNEI developed a PV test bed located at Pu'u Wa'a Wa'a ranch on the Kona coast of the Big Island of Hawaii. Initially we selected seven different PV technologies for testing consisting of poly-crystalline, mono-crystalline, amorphous, and mixed technologies. The test modules comprise 200 W units, tilted at 20°, with maximum power point trackers, via small inverters connected to the grid or via charge controllers connected to a battery and load bank. The data is sampled at 1 Hz and stored in a database for visualization and analysis. This paper presents a description of the test bed design, the high data rate Data Acquisition System (DAS), and initial experimental results.

• Performance of photovoltaic is dependent on the PV module's design, material, and environmental variables
• If a portion of PV array or the entire array is covered with clouds then an immediate power loss will occur
• The impact of mentioned power loss on the grid will be exacerbated if a sudden change in the load demand happens at the same time
• The battery voltage needs to be maintained below its float voltage in order to reach MPP of the module
• A graphical user interface is created under a Matlab environment in order to analyze and visualize data
• MPPTs operation is more efficient with low voltage modules
• Charge controllers show an average efficiency around 90 percent

Modelling of a residential solar stand-alone power system[7][7][7][7][7][20][20][edit | edit source]

Abstract Modelling of residential solar powered stand-alone power system comprising photovoltaic (PV) arrays, and a secondary battery is presented. Besides, an economic study is performed to determine the cost of electricity (COE) produced from this system so as to determine its competitiveness with the conventional sources of electricity. All of the calculations are performed using a computer code developed by using MATLAB®. The code is designed so that any user can easily change the data concerning the location of the system or the working parameters of any of the system's components to estimate the performance of a modified system. The system output was calculated for Cairo city (30°01'N, 31°14'E) in Egypt. It was found that maximum amount of hourly radiation on the photovoltaic arrays tilted by an angle of 30° facing south is 945.8 W/m2 and is obtained in April. Also, the average maximum efficiency of the modelled 200 W solar cells was 12.098% with a maximum power of 162.172 W. The system which has an efficiency of 10.283% showed a great ability to satisfy the estimated demand load. The COE obtained from the system was found to be 44 cents/kWh over 20 years of its operation. This cost is high when compared with 30 cents/kWh for electricity produced using an off grid diesel generator and 6 cents/kWh for a similar grid connected house. However, an extra cost of 1.6 cents/kWh exists in case of considering removing CO2 produced by the two conventional sources.

• During darkness, the solar cell produces neither a current nor a voltage
• The main cost items that are included in the cost estimations are photovoltaic panels, battery, DC/AC converter, and operating and maintenance cost
• In an ideal photovoltaic cell series loss and leakage to the ground are zero

Study of a standalone wind and solar PV power systems[8][8][8][8][8][21][21][edit | edit source]

Abstract This study utilizes hourly average wind speed and hourly total global solar radiation data for the years 2007-2009 to study the energy yield from (i) a standalone wind power system of 6 kW rated capacity and (ii) a standalone 6 kW photovoltaic (PV) power system. These wind and PV power systems are installed in the campus of King Fahd University of Petroleum and Minerals at Dhahran, Saudi Arabia. The annual energy yields from standalone wind and solar PV power plants each of 6 kW installed capacity were found to be 8,000 kWh and 10,364 kWh with respective capacity factors of 14.3% and 19.7%. The propose wind turbine could displace 2 tons of greenhouse gases annually from entering in to the local atmosphere and the solar PV power plant could be able to reduce around 3 tons of these gases annually.

• The RETScreen Clean Energy Project Analysis Software is used to calculate the energy that is yielded from wind and solar systems

Performance enhancement of PV Solar System by mirror reflection[9][9][9][9][9][22][22][edit | edit source]

Abstract In this paper, a study has been made to enhance the performance of Solar Home System (SHS) by a very simple method where the investment cost is negligible. Like any other developing country of the world, most of the rural people of Bangladesh do not receive grid power due to shortage the of primary energy sources and the high cost involved for transmission & distribution system. To stimulate the economic activities among the rural population and to enhance the literacy rate, Bangladesh government has taken up a massive plan to sell SHS among the rural masses on a very soft loan. Although the per unit energy cost for PV home system is quite high, improvement in the performance of SHS will significantly reduce the per unit energy cost of the SHS. Bangladesh receives an average solar irradiation of 3.82-6.42kWh/m2 and considering the total area of Bangladesh and assuming the efficiency of solar system to be 10%, 5.2×109 kWh of electricity can be generated annually. Roughly 60% population of the country do not have access to grid electricity and are mostly dependent on bio mass to meet their energy requirement. However, solar home system is becoming popular day by day and even poor households are now becoming interested to purchase solar home system due to its various advantages. Around half a million solar home systems have already been installed in different parts of Bangladesh and the annual growth rate is around 5%. One of the major limitations of the solar home system is its extremely poor efficiency. Lot of research is going on to improve the performance of the solar panels. Sun tracking is a method frequently adopted for performance enhancement. However sun tracking devices need expensive control and drive equipments and the power for these equipments has to be provided by the solar panel and the battery installed within the solar home system. Due to cost and frequent maintenance requirement, such tracking systems are not popula- - r in Bangladesh. Even a slight enhancement of the performance of solar cells will drastically reduce the overall per unit energy cost of the solar home system. In this paper, performance enhancement of solar panel by direct reflection of light has been studied experimentally. In order to make a comparative study, readings of the output of solar panels were taken under three different conditions simultaneously. The conditions are: i) panel output when the panel was inclined at 23.5° with the horizontal ii) panel output by tracking the sun and iii) panel output by fixing plane mirrors at the East-West ends of the panel edge with the panel fixed at 23.5° with the horizontal. Encouraging results were obtained with such reflectors installed with the solar panel. Results from the practical data show that by using mirrors, an average increase of around 25% in the short-circuit currents, as high as that of sun tracking, can be achieved. And as a result of the reduced complexity and zero power consumption of the mirror system, as compared to that of sun tracking system, use of mirrors will be more economically viable over sun tracking. Moreover, installation of mirrors is cheap, simple and does not require any additional complicated equipments or devices.

• Three methods are used in order to improve performance of PV system, sun tracking method, diffused reflectors, mirror reflectors
• Sun tracking method increase the output power by 20%, but it consumes power for its own operation and a complicated maintenance is required
• Diffused reflectors are subjected to damage due to gusty winds
• Mirror reflectors are cheap and the current output will be higher by using these mirrors than sun tracking method, and mirrors are placed at an angle of about 120 degree with the panel's horizontal surface

Economical assessment of solar electricity from organic photovoltaic systems[10][10][10][10][10][23][23][edit | edit source]

Abstract Small size polymeric solar cells at laboratory scale have recently reached efficiencies up to 8.3% [1]. The rapid progress in manufacturing methods which allow a continuous roll-to-roll production indicate that this high efficiency could be within reach for larger modules [2]. Life cycle analysis has evaluated the environmental impact of this emerging technology and allows us to compare the carbon emissions mitigation potential of the polymeric solar technology with other photovoltaic technologies, other renewable energy sources, or fossil fuels [3]. In this work, a detailed economic calculation on the cost of electricity production by a 1kWp grid-connected organic photovoltaic system has been performed. Building on the detailed material inventory and the module manufacturing process for the production of organic photovoltaic modules [2], the economical cost of a 1kWp organic photovoltaic system has been calculated taking into account the materials, direct process, labour, balance of system components, design and maintenance costs and using a well established methodology for the economical analysis [4,5]. Assuming values for the performance ratio of the PV system, insolation level, inflation and interest rates, the levelised cost of electricity (LCOE) from an organic photovoltaic system is calculated. The interest of organic photovoltaic technologies is mainly the promise of very low-cost for module components and therefore cheap solar electricity. Our calculation demonstrates that this statement is within reach for an already tested manufacturing process which allows the fabrication of organic photovoltaic modules. The cost of solar electricity is calculated to be 0.26 euro/kWh for 3% efficiency modules of 5 years lifetime, assuming a performance ratio of 0.85 and an insolation of 1700kWh/m2 per year. This reduces to 0.11 euro/kWh if cells with the module reach the current record efficiency of 8.3% and the module lifetime is extended to 10 years. A sensitivity ana- ysis has been performed and it shows the importance of improving the lifetime of the organic PV modules to around 10 years. The cost of electricity from an organic photovoltaic system could be more favourable than that obtained for an equivalent inorganic (silicon-based) system and could attain grid parity in the coming years.

• The interest of organic photovoltaic technologies is mainly the promise of very low-cost for module components and therefore cheap solar electricity

A cost analysis of photovoltaic technologies under Jamaica'S climatic conditions[11][11][11][11][11][24][24][edit | edit source]

Abstract With the spiraling cost of imported fossil fuels and high values of insolation, the Caribbean region hopes that photovoltaic (PV) technologies will provide a more cost effective and secure energy solution. PV performance parameters are given under Standard Test Conditions (STC). Since STC is never realised under normal operational conditions (NOC) within Jamaica's climate, it is essential that we investigate the actual performance characteristics and the most cost effective technology for Jamaica. We present the results of energy delivered by 8 commercially available PV modules under NOC and hence determine the levelised cost per kWh delivered over their average warranted lifetimes.

• Commercial photovoltaics are classified in three main groups, crystalline, thin films, organic PV's
• Crystalline PVs produced the most energy for 1996, but their high purchase price reduced their cost effectiveness
• The energy production of thin film PVs are generally lower than crystalline PVs
• Mono/multi has the highest energy production of 125 KWh per square meter but a a:Si produces its energy at the lowest cost for 1996

improved photovoltaic energy output for cloudy conditions with a solar tracking system[12][12][12][12][12][25][25][edit | edit source]

Abstract This work describes measurements of the solar irradiance made during cloudy periods in order to improve the amount of solar energy captured during such periods. It is well-known that 2-axis tracking, in which solar modules are pointed at the sun, improves the overall capture of solar energy by a given area of modules by 30–50% versus modules with a fixed tilt. On sunny days the direct sunshine accounts for up to 90% of the total solar energy, with the other 10% from diffuse (scattered) solar energy. However, during overcast conditions nearly all of the solar irradiance is diffuse radiation that is isotropically-distributed over the whole sky. An analysis of our data shows that during overcast conditions, tilting a solar module or sensor away from the zenith reduces the irradiance relative to a horizontal configuration, in which the sensor or module is pointed toward the zenith (horizontal module tilt), and thus receives the highest amount of this isotropically-distributed sky radiation. This observation led to an improved tracking algorithm in which a solar array would track the sun during cloud-free periods using 2-axis tracking, when the solar disk is visible, but go to a horizontal configuration when the sky becomes overcast. During cloudy periods we show that a horizontal module orientation increases the solar energy capture by nearly 50% compared to 2-axis solar tracking during the same period. Improving the harvesting of solar energy on cloudy days is important to using solar energy on a daily basis for fueling fuel-cell electric vehicles or charging extended-range electric vehicles because it improves the energy capture on the days with the lowest hydrogen generation, which in turn reduces the system size and cost.

• Solar energy is a way to boost the future hydrogen economy via the electrolysis of water
• The best configuration overall fixed configuration for PV installations is one in which the modules face south and are tilted with respect to the ground at an angle equal to the site latitude
• The largest amount of solar energy can be obtained using a mechanical tracking system so that the modules are always facing the sun
• Two axis solar tracking increases the solar insolation by over 50% relative to that for PV modules with fixed horizontal orientation, by 30% relative to PV modules with a fixed latitude tilt
• For cloudy conditions, orienting solar modules toward the zenith captures the most solar energy

Simplified method of sizing and life cycle cost assessment of building integrated photovoltaic system[13][13][13][13][13][26][26][edit | edit source]

Abstract This paper presents methodology to evaluate size and cost of PV power system components. The simplified mathematical expressions are given for sizing of PV system components. The PV array size is determined based on daily electrical load (kWh/day) and number of sunshine hours on optimally tilted surface specific to the country. Based on life cycle cost (LCC) analysis, capital cost (US$/kWP) and unit cost of electricity (US$/kWh) were determined for PV systems such as stand-alone PV (SAPV) and building integrated PV (BIPV). The mitigation of CO2 emission, carbon credit and energy payback time (EPBT) of PV system are presented in this paper. Effect of carbon credit on the economics of PV system showed reduction in unit cost of electricity by 17–19% and 21–25% for SAPV and BIPV systems, respectively. This methodology was illustrated using actual case study on 2.32 kWP PV system located in New Delhi (India).

• The cost of PV system components are determined based on the size of PV system components
• The life cycle cost analysis for the PV system is presented for estimation of unit cost of electricity generated from the stand alone PV and building integrated PV
• The life cycle cost analysis is carried out assuming useful life of 30 years for PV array system and 5 years life for battery bank