Does system performance fall when it's hot outside?
Silicon PV panels and inverter electronics lose efficiency at high temperature — textbook silicon derates around −0.3 to −0.5% per °C above 25 °C cell temp. This page checks whether the effect is visible in your own data.
Method: at each midday (10:00–15:00 local) intraday snapshot with irradiance > 300 W/m², compute a performance coefficient = solar_w ÷ solar_radiation_w_m2 (units: effective m²). If the system heat-derates, the coefficient should slope downward as ambient temp rises. A second daily view compares actual kWh to a PVWatts-uniform expected, filtered to sunny days only.
Date range
61 days of overlap
Samples
midday, irradiance > 300 W/m²
Slope
≈ -0.42% / °C
R²
No linear signal
No meaningful correlation yet (R² < 0.05). If derate exists, it's buried under sun-angle / cloud noise at current sample size.
Daily ratio = actual solar kWh ÷ (PVWatts monthly projection ÷ days in month). Limited to days whose 10–15 local mean brightness exceeds 80,000 lux so cloud variance doesn't dominate. Slope on this view ≈ 0.46% / °C (n=39, R²=0.017).