Frustrated by continually needing to balance solar forecast vs. battery capacity vs. house load... I set about writing a Home Assistant integration to automate the calculations, and ensure that the batteries are charged to the perfect level using an off-peak tariff (i.e. Octopus Go) in order to maximise solar but minimise grid use.
In brief, the integration ensures that your home batteries are charged to the optimal level when the forecasted solar output drops below your daily average usage and will also ensure that, given a day where the solar forecast is greater than your daily average usage, the battery has enough charge to last until dawn.
To further ease managing the battery state, the integration includes a switch to boost (+1kW) the battery charge and a second switch to charge fully; this is useful for times when you expect a higher than average load.
More details here -> https://github.com/nathanmarlor/foxess_em
Would appreciate any feedback/feature ideas/bugs etc.