Performance enhancement of PV Solar System by mirror reflection

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 [1]. 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 popular 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.