Adding a forecast for solar production into Home Assistant is very easy and done in under 5 minutes, thanks to Forecast.Solar. They provide an API which does the forecast itself using data you provide about your PV installation. Their basic plan is even free to use!

Enabling Forecast.Solar

In your Home Assistant settings, add a new Integration. Search for Forecast.Solar

Configuring Forecast.Solar

You can configure Forecast.Solar directly after enabling the integration, as well as later in the integrations overview.

If you have an API Key (because you have a Personal, Personal Plus or Professional/Professional Plus Account) you can enter it, but you don’t need one for basic functionality, since Forecast.Solar provides basic service for free (Forecast for today and tomorrow). If you need more, look at their website for more options.

Enter the declination which your PV installation has. The declination affects the solar yield the panels produce.

Enter the Azimuth to which your solar panels point to. 180 degrees = South

Enter the Watt peak of your PV installations, and if applicable a damping factor (if for example you have a house blocking the sun in the morning and afternoon hours).

At last, you have to enter your inverter size.

Adding a panel with forecast information

Wherever you want to add your panel, search for the respective entity of Forecast.Solar you want to add, like energy_production_today or energy_next_hour, and add it to your dashboard.

That’s all!