Low Light Solar Production and Top End Clipping – A Comparison

One of the first things I noticed with my solar setup was that on a purely sunny day, I lose the top few percent of my curve. What is happening here is that the micro-inverters mounted on each of my 365 watt panels top out in output around 307 watts.

My first thought when I discovered this was “Well that is inefficient. We are losing power we should be getting from the top of the curve.” Then I thought about this some more.

The two images below are two solar systems on a full sun day. One is mine, the other is a larger (~20%) solar system using panels that are rated for 340 watts. The yellow in these images represents solar production. Look at these two images and you tell me who gets the most production overall from their system. Keep in mind that the other system is a larger system.

While both systems top out at 8.6kW, the one on the left (my system) clearly generates more earlier in the day. It generates enough more in the morning hours to give it a sizable advantage for the rest of the day, even though it is clipped at the top of the curve.

The bottom line… on a day of full sun my system generates about 2.5x what we use, so that top section being clipped off is not a big deal. On days of less than perfect sun, especially cloudy days, (like this day) the REC panels are superior with their low light production. So while we are a bit inefficient at the very top of the curve in perfect conditions, we fill in well around the bottom of the curve and fill out the curve much better in low light conditions.