Clipping

Clipping happens when the panels could deliver more power than the inverter is allowed to put out. The inverter holds its output at its maximum and the extra is lost.

Plug-in kits are designed to clip. The law caps a plug-in microgenerator at 800 W of AC output (SI 2026/848), but the product specification allows up to 2,000 W of panels (IPS §4.1). So a kit with more panel power than 800 W will clip around midday on bright days. In return, it produces more in the mornings, evenings and winter, and on cloudy days, when the panels are well below their rating.

Whether extra panels are worth it depends on how much is lost to clipping compared with what’s gained at other times, and that depends on direction, tilt and location. Our calculator models this hour by hour using PVGIS hourly data (PVGIS). Hourly averages smooth out short peaks, so real clipping will be a little higher than we show.