Grid-connected Solar Photovoltaic System Research Articles

Real-time prediction models for output power and efficiency of grid-connected solar photovoltaic systems

This paper develops new real time prediction models for output power and energy efficiency of solar photovoltaic (PV) systems. These models were validated using measured data of a grid-connected solar PV system in Macau. Both time frames based on yearly average and monthly average are considered. It is shown that the prediction model for the yearly/monthly average of the minutely output power fits the measured data very well with high value of R2. The online prediction model for system efficiency is based on the ratio of the predicted output power to the predicted solar irradiance. This ratio model is shown to be able to fit the intermediate phase (9am to 4pm) very well but not accurate for the growth and decay phases where the system efficiency is near zero. However, it can still serve as a useful purpose for practitioners as most PV systems work in the most efficient manner over this period. It is shown that the maximum monthly average minutely efficiency varies over a small range of 10.81% to 12.63% in different months with slightly higher efficiency in winter months.

Integrating photovoltaic and power converter characteristics for energy extraction study of solar PV systems

Solar photovoltaic (PV) energy is becoming an increasingly important part of the world’s renewable energy. A grid-connected solar PV system consists of solar cells for energy extraction from the sun and power converters for grid interface. In order for effective integration of the solar PV systems with the electric power grid, this paper presents solar PV energy extraction and conversion study by combining the two characteristics together to examine various factors that may affect the design of solar PV systems. The energy extraction characteristics of solar PV cells are examined by considering several practical issues such as series and parallel connections, change of temperatures and irradiance levels, shading of sunlight, and bypassing and blocking diodes. The electrical characteristics of power converters are studied by considering physical system constraints such as rated current and converter linear modulation limits. Then, the two characteristics are analyzed in a joint environment. An open-loop transient simulation using SimPowerSystem is developed to validate the effectiveness of the characteristic study and to further inspect the solar PV system behavior in a transient environment. Extensive simulation study is conducted to investigate performance of solar PV arrays under different conditions.

Life Cycle Cost Analysis of Residential Grid-Connected Solar Photovoltaic Systems in Florida

The main concern for adopting solar PV is the cost of PV systems and their higher unit price than grid price. This study uses four cities in Florida as cases to investigate the life-cycle cost, in the form of equivalent annual cost (EAC), and unit electricity price of various scenarios that apply solar photovoltaic (PV) system technologies to residential buildings. The study shows that currently the EAC of using distributed standalone PV systems increases when more electricity is generated by such systems. The unit electricity price is essentially determined by the aggregate unit price of electricity, which includes two parts, electricity consumption of a residence from both grid and PV systems. When the unit electricity price is less than the unit grid price during the study period, the investment on PV system becomes feasible. However, other factors may have a great impact on the life cycle cost including the cost of batteries, the replacement cycle of batteries and inverters, net metering, and rebate and incentive programs. The analyses in this study suggest that properly handling those factors may lead to a significant cost reduction, which in turn makes PV systems more affordable.

99/03267 Modeling the altitude effect on solar UV radiation

This paper presents a performance analysis and economic viability of a 10 kWp grid-connected solar photovoltaic (PV) system installed at Maungaraki school, Wellington, New Zealand under the ”Dynamis Project”. The system consists of 40 panels and two units of 5 kW power converters with a communication capability while the distribution grid serves as a virtual storage. The excess power generated at low load condition during holidays and weekends is exported to the grid. With the system in operation since 2014, performance parameters based on International Energy Agency Photovoltaic Power System Programme (IEA PVPS), Clean Energy Council industry guide and IEC 61724 standard are evaluated. The final yield ranged from 1.1 to 4.9 h/d. The performance ratio (PR) varied between 76 and 79%, giving an annual PR of 78%. In addition, from the economic evaluation of this system at 4%, 6% and 8% discount rates, the levelized cost of energy are 12.1, 14.1 and 16.2 c/kWh respectively, with a simple payback period of 6.4 years. Overall, the total amount of power consumed annually from the grid reduced significantly by 32%. In monetary terms, the school's expenditure on power bills reduced effectively by 45% and was able save about NZD $4700 in 2014.

Interfacing a solar photovoltaic system with the national electricity grid in Malta

A 1.8 kWp grid-connected solar photovoltaic system is being monitored at the Institute for Energy Technology, since June 1996. The average performance ratio for 22 months of operation was found to be 0.715, which translates to a final yield of 3.44 kWh/kWp/day. The average final efficiency was found to be 7.6%. These values exclude the month of October 1997, during which the system was not operating. Problems encountered, relating to the interface between the electric utility grid and the PI' system are discussed.