Preliminary Design of a “Soparometer”: Instrument to Measure the Rated Peak Power of a Solar Panel

The main determinant of the cost price of a solar panel in the market is the rated peak power as measured under standard laboratory conditions (cell temperature of 25?C, solar irradiance of 1000 W/m2 and an air mass of 1.5). An indirect method (considered indirect since the measurement is done under nonstandard laboratory conditions) is adopted here in order to approximate with some degree of certainty the rated peak power of a solar panel. It involves the use of a characterized solar module of known peak power for comparison to the solar panel under measurement when both are subjected to the same ambient conditions. Two electronic loads are used to drive both the test module and solar panel at their respective maximum power points in order to determine by how much in magnitude the power of the solar panel surpasses that of the module. The peak power of the solar panel is obtained using the assumption that the magnitude by which its peak power surpasses that of the module remains constant provided they are subjected to the same ambient conditions. Using this method, multiple measurements were conducted on two solar panels rated at 100 W and 50 W by the manufacturer and the results obtained were 85.73 W and 43.26 W respectively depicting a 14 percent and 13 percent discrepancy. It therefore remains a promising method of measurement if enhanced and fine-tuned.