One more interesting view into ‘statistical accuracy’. Finally compared my hourly solar data for the past 6 years or so from my inverter vs. the NREL hourly simulation data. Same results as I saw against my Sense solar data (no surprise), but I was able to look across 6 years. Guessing that this might be of interest to @ixu as well.
Hourly Comparison - NREL vs Real
Still a butterfly wing. The few points up near the top are places where Solarcity missed an hourly reporting and doubled-up on the next one (another challenge with making sense of data). I think the “butterfly wing” occurs because my panel geometries (azimuth, incline) don’t square with the NREL or solarR conventions, but it doesn’t matter when integrating over the course of the day. Shortfall in the morning vs. the NREL predictions is made up for by a surfeit in the afternoon/evening.
Daily Comparison - NREL vs Real
Approaching linear
Monthly Comparison - NREL vs Real
Linear - Now you know why SolarCity was able to sell me a power purchase agreement with a money back guarantee on a yearly basis.
