Solar Power in Central Europe

Solar potential

My house has excellent solar potential. It’s roughly on 47 degrees north. One entire side of the roof has an azimuth of about 220 degrees and a declination of 31 degrees. The total usable surface for the panels is 62 square meters.

The roof is big enough for 36 panels. 24 at a declination of 31 degrees and 12 at 10 degrees. With 330 wP panels this sums up to 11.8 kWp. The local utility company that installed the system projects a yearly production of 12.2 MWh.

Current results

The system has been running since December 2020. The best day so far was the 30th of May 2021 when the system produced 81.3 kWh in a single day. Unfortunately the summer of 2021 was exceptionally rainy for Europe, so the system didn’t quite reach it’s full potential, but even so it has produced 9.9 MWh in the first 8 months of the year. Given that the darker winter months are now coming, the projected 12.2 MWh seems spot on.

Surprises so far

I was surprised to see that the panels do not produce peak output in the summer months. This is when I learned that panels are usually rated at 25 degrees Celsius and in the sumer my roof was easily going over 30 degrees. The loss was substantial. The system did not reach it’s peak value even once in August, but it overshot the peak rated value in May. So far the largest value reported by my power inverter was 13.1 kW, and the rated peak is only 11.88 kW. This was on a sunny but windy day in May.