Analysis and comparison of performance of photovoltaic systems from the “Counting the Sun” public awareness campaign on PV performance

Abstract

Detailed analysis of 5000 systems that took part in the 2014 measurement campaign “Counting the Sun” was performed as besides the weekly yield also system descriptions were available. With average energy yield of 33.4 kWh/kWp, and average performance ratio of 0.74 for all systems, performance ratio was found to be dependent on the ratio of inverter DC nominal power and system DC rated power. For low cost inverters, this ratio was 1.16, while for high cost inverters it was 0.95. Apparently, expected better performance does not warrant higher capacity inverter, in the case of high cost inverters. However, due to the 1-week period, performance ratio was found not to be dependent on this ratio. Also, different components (modules, inverters) do not conclusively influence performance ratios. A longer monitoring period is expected to lower variation of these values such that statistically relevant differences can be observed.