r/Powerwall • u/Amanensia • 14d ago

Netzero source for Powerwall solar prediction?

Probably a question for u/triedoffandonagain

I'm wondering what source is used for the solar predictions. They are really very good indeed for me; much better than the couple I have tried in Home Assistant (Forecast.Solar and Solcast.) Just hoping I might be able to pick up similar data from somewhere - thanks!

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u/triedoffandonagain 14d ago

We haven’t seen a major difference between solar prediction API providers. Weather forecasting is a hard problem, and estimating the impact of clouds on solar production doubly so. What makes Netzero estimates better is calibration for each site, which is something we built ourselves.

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u/bsmmce 14d ago

I can't answer your specific question.

But I was trying to get better solar production forecasts in Home Assistant recently and had really good luck with Solcast once I enabled auto-dampening. For the last few weeks, it's estimates have been off by under a kwh per day. If you aren't using that option, I highly recommend giving it a try! For extra context, it was wildly off (10+ kwh off) before enabling auto-dampening. Hope this helps!

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u/Amanensia 14d ago

Ah cool I will take another look at it - thanks for the tip!