Hi,
We are using the Solcast irradiance forecast, so the irradiance forecast you see in VRM is 1:1 that of Solcast.
We take this irradiance forecast and add some more factors to model the solar yield forecast. So as we build on the Solcast data and add more varying factors, the solar yield forecast is less accurate than the irradiance forecast, that’s very logical.
In the screenshot below the green graph is the Solcast deviation from actual solar irradiance, and the purple line is VRM’s deviation from actual solar yield. You can see that both follow the same trend, meaning that also Solcast struggles with changes in weather. As solar yield has more factors to account for than only irradiance, the impact of an inaccurate day is bigger in VRM compared to only solar irradiance data.
What we do to correct for that is - besides continuously retraining the model so it understands the impact of weather changes - is that when the algorithmic model deviates too much on a day or hour, we switch to a more simplistic mathematical model, which just takes solar irradiance forecast and adds a ‘rule of thumb’ calculation of what solar yield could be.
As DESS re-schedules every 15 minutes, even deviations from solar forecast will be corrected in terms of the best strategy to save money.
We are working on a page that explains solar forecast and how Dynamic ESS performs with it, so hopefully that clarifies it a bit.