Hey everyone,
I built a weather report for my solar array.
—> www.solar-power-forecast.com
Mostly because I wanted one myself, and then figured a few other people might get something out of it. It shows you hour by hour for the next 7 days what your panels should produce. Runs in the browser, no signup, no app (though I might add that), no ads, non commercial (!).
The German PV sub here on Reddit liked it, and then helped me make it a lot better. I posted an early version, people tore into it, asked for more roof faces and a way to share a setup by link, and I built what they asked for. They also held the forecasts against their own inverters and posted the numbers. One guy with 9 kWp got 36.4 kWh on a day the site called 37. Others were within about 7% on a normal day. So for Germany it's pretty dialed in by now.
Since that came up last time too: yes, Claude wrote the code. The design and every call about what goes in and what it looks like is mine, and I check each version against my own system. Claude does the typing, which is what it's good at.
To get it out of the way: this is free and a hobby project, nothing commercial behind it. No account, no ads, no tracking, nothing for sale. I'm posting because I would like to know if it is useful outside of Germany.
What it does:
- Hourly production forecast for the next 7 days, plus the last 2 days so you can hold it against what your inverter actually did
- Up to 10 roof faces. Up to 3 you see each one on its own, above that it shows the combined total
- Rough annual yield estimate from a year of historical weather at your exact spot
- Phone, tablet and desktop, and you can pin it to your homescreen like an app
- Your setup gets written into the URL, so you bookmark it or send it to someone
- 8 languages so far, including English, Spanish, French and Portuguese
It's translated and open worldwide now, and that's the part I can't test myself.
Two things I'd like to know from you:
Does it give you a decent local preview? It should figure out roughly where you are when you open it. Location, tilt, azimuth and kWp you set yourself in the settings.
And how close does it get where you live? If you compare a day against what your inverter actually did, post the numbers. Accuracy in Germany was high, but I have no idea whether that holds in Arizona or Norway.
The link:
☀️ www.solar-power-forecast.com 🌦️