Capacity > 4 KWP errors

[peterdudfield]

Following on from #130, we can see errors when large capacity are used. This is becasye the model is trained on 1-4 KWp sites.

I suggest the following

1. Check in if capacity>4
2. If so, reduce capcity to 4 and add warning message
3. run model
4. scale results back to original capacity