ᐅ Photovoltaic System: Output in Poor Weather Conditions

Hello,

a few days ago, our photovoltaic system was installed. Although it is not yet connected to the grid, it is already producing power for self-consumption.

For fun, I monitored the production, and yesterday it dropped significantly during light rain/heavy cloud cover. Does this happen to you as well?

Are you surprised that the output drops significantly when there is no sunlight?!

No, I’m not surprised! I’m interested in how much the yield is roughly reduced by in percentage terms during rain and similar conditions.

AndreasPlü schrieb:

Just for fun, I monitored the production and yesterday it dropped drastically during light rain/heavy cloud cover. Is it the same for you?

Yes, that is completely normal. Cloud cover can quickly reduce solar radiation by up to 90%, which results in a similar drop in output. However, this is already accounted for in yield forecasts, for example from PVGIS.

Bright sunshine, but when a cloud passes over the house, at least 50% of the output is lost. I can even notice the effect of the outside temperature. At 30°C (86°F) outside, I only get about 85%-90% of the output compared to 18-19°C (64-66°F). The highest daily production this year was in May, with 223 kWh. In July, the peak value was 201 kWh, clearly showing the influence of temperature.

OK, I’m a newbie when it comes to photovoltaic systems.

I was just surprised yesterday because it was very cloudy and drizzling a bit. The output was around 150 W with a 6 kWp capacity and a SolarEdge system. OK, there are also general shading issues.

Still, it has produced 110 kWh in the 5 days since connection, which matches the expected yield forecast for August. I was just surprised by the extremely low output at times during the middle of the day.