What tool to use for Solar power generation Forecasting

raffertyh1990 · 24-02-2026 10:40PM #1

Greetings!!

Which tools do you use for next-day or day-ahead solar power generation forecasting, other than your manufacturer's default dashboard?

I know 4 tools that works good - 1) PVGis, 2) Solcast free tier, 3) MeteoSource and 4) Solar-forecast.com

All of them has thier own issues and positive aspects - one feels superior to another sometimes - yet Solcast and Solar-Forecast.com (for me at least) work great

I am open to hearing your suggestions on these - any new tool you want to suggest?

Thanks you so much!!

ECO_Mental · 24-02-2026 11:29PM

https://www.boards.ie/discussion/2058433289/what-tool-to-use-for-solar-power-generation-forecasting

Solcast.. According to this fella

https://youtu.be/SAwSA6C4-Qw?is=QuBU1kKtSwwJlaWT

ECO_Mental · 24-02-2026 11:29PM

https://youtu.be/SAwSA6C4-Qw?is=QuBU1kKtSwwJlaWT

Tree · 25-02-2026 10:53AM

Solcast, and someone on here has a nice python script to go with met éireann for home assistant, but I have a bogey memory and no quick link to it.

JayBee66 · 26-02-2026 11:46AM

Maybe it's just my part of this eternally wet island but PV prediction is never going to be that accurate. I switched off Home Assistant over a year ago (Solcast was never that accurate) to trust my changed habits and minimal optimisation of device software.

Your best predictor is a few years of data and monthly/daily averages derived therefrom.

You are unlikely to need to know exactly what you are going to produce tomorrow but long-term trends will help you "seasonalise" your year.

My four years of data let me know when to switch between immersion and solar thermal heating. When to turn on overnight battery charging for the darker months and when to turn it off and let the early Sun charge the battery. Whatever suits your lifestyle.

ECO_Mental · 26-02-2026 01:05PM

True that I think its a waste of time trying to predict PV to work any automations off it. The best you will get is yeah tomorrow should be ok or not just to give you an idea. I have a Victron system for the last few months and they use Solcast as well and to be it seams fairly accurate. Again I only use it as a tool to see if tomorrow is going to be a disaster or not. None of my energy automations rely on it.

What tool to use for Solar power generation Forecasting

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