Solar Forecast versus Solar Irradiance

Hi All

I’m trying to work out how much spare energy I’ll have at the end of the day, and while the Victron Solar Production Forecast is usually pretty accurate, it doesn’t always factor in system limitations like when the batteries are full or when high-power loads kick in. For example, around 9:15 AM on my system, I start seeing production limits because the batteries are charged, and the forecast stops lining up with the actual yield.
To get a better idea of my available energy, I’m focusing on the solar irradiance forecast and solar PV forecast before the system starts limiting production. By looking at this data and adjusting for when the batteries are full or extra loads are turned on, I can calculate what the total energy for the day should be. Then I subtract the energy used for charging batteries and any loads, which gives me a clearer estimate of how much energy I’ll have left to play with by the end of the day.
If anyone can help how I can work this out or if there is a formula to go from irradiance forecast to get me yield forecast it would be appreciated.

Thanks

Dave