Edinburgh Napier University

  In the past few years, there was an increasing popularity of portable solar chargers for providing access to clean affordable electricity to remote locations in developing countries. Looking at the surge in demand, it is also important to reduce the environmental impact of portable solar chargers. Solar photovoltaic (PV) concentrators have the potential to reduce the embodied energy and thus the embodied greenhouse gas emissions, human-toxicity and eco-toxicity potential during production, recycling and disposal stages of silicon PV solar panels. Yet, no solar PV concentrator designs have been proposed for portable solar systems for developing countries. Recently, a novel concentrator known as genetically optimized circular rotational square hyperboloid (GOCRSH) concentrator was developed to address this problem. This paper evaluates the performance of four types of GOCRSH concentrators; namely GOCRSH_A GOCRSH_B, GOCRSH_Crh and GOCRSH_D that have a geometrical gain of 3.73x, 3.34x, 3.80x and 4.07x respectively. The experimental analysis of these concentrators was performed indoors under standard test conditions, i.e. 1000 W/m2, AM 1.5G and at a temperature of 25 ˚C to characterize the concentrators at normal incidence and to determine their angular response. Firstly, the fabrication process of the prototypes is described. Secondly, the GOCRSH concentrated devices and the reference cell are characterized at normal incidence, obtaining the current–voltage (I-V) and power-voltage (P-V) curves. Next, the angular response of the concentrators is obtained at various angles of incidence of up to ± 70° in increments of 5°. Mismatches between the simulation results and the experimental results are identified and possible error sources leading to the mismatch are discussed. Lastly, the increase in solar cell temperature under constant illumination and its impact on the solar cell performance is recorded for the GOCRSH_A concentrating device. From the indoor experiments, it was found that the prototypes were showing the maximum power point ratio under normal incidence of 2.9x, 2.6x, 3.9x and 2.7x with the GOCRSH_A GOCRSH_B, GOCRSH_Crh and GOCRSH_D respectively.