Double check panel math


Photon Sorcerer
Jan 18, 2021
Is ‘PV Forecast’ related to PVWATTS?
I don’t know. Maybe? It was called PV Forecast or forecaster.
But it ain’t a very good tool.

It’s mostly like an extrapolation of a ten day weather forecast into a watts forecast. You tell it your inverter size and panel watts, location/azimuth and it tells you what your charging output might be.
I made way more than forecast most of the time especially if cloudy. If partly cloudy or partly sunny, it failed out royally with enough inconsistency that it just wasn’t a useful tool. Way more, way less, no predictability.
How I started was when I installed the 120V fridge I expected to struggle so I looked up some apps.
As it turned out the system outdid itself brilliantly until recently as the days got shorter. The app was often 50% incorrect for the five weeks it took for me to get disgusted.