Long-term Performance of Concentration Photovoltaic (CPV) System

Abstract

The maximum rating efficiency tested in the laboratory of solar cells cannot reveal the actual performance of a solar photovoltaic plant due to the intermittent nature of solar energy and the variations in the field conditions. Therefore, a concentration photovoltaic (CPV) system is developed for the long-term performance test. It consists of 2x4 and 2x2 Fresnel lens arrays, concentrating sunlight onto a small area 5.125mm2 of InGaP/InGaAs/Ge multi-junction solar cells with x548.24 geometric concentration. Meanwhile, an active tracking sensor based on an octagonal pattern arranged photosensors array is installed to keep high accuracy and stability track during operation. Moreover, the Labview software records all comparative data like Global Tracked Irradiance, Direct Normal Irradiance and Global Horizontal Irradiance. The daily performance shows the system's precise tracking and stable working, which is the basement of the success of the long-term performance test. And the long-term performance analysis indicates the long-term average efficiency is 20.2% in Saudi Arabia for the CPV system, which is the real potential of a solar plant, with a much higher electricity production potential than other systems. Combined with the literature results of conventional photovoltaic and CPV systems in Singapore and the concentrated solar power system in Qinghai, China, an actual field performance design chart is formed. Based on all the above, a quick and highly accurate estimation of photovoltaic potential can be made for any region and a suitable photovoltaic system can be chosen and designed per load demand. From the application perspective, a heat engine model is supposed to be operated between the Sun's photosphere and the Earth's surface according to classical thermodynamics to evaluate the performances of different solar photovoltaic systems in a common energy platform known as the standard solar energy. When combined with seawater reverse osmosis plant for freshwater production, the CPV system still leads the water production comparing other systems due to higher 2nd law efficiency in thermodynamics.