How do I determine the size of inverter I need for my installation?

The optimum inverter load (expressed as a percentage of the kWp output of the panels in relation to the kVA output of the inverter) is generally between 100% and 130%.

Below this range, the inverter won't start if panel output doesn't meet the minimum required, which can lead to efficiency losses in the system.
Beyond this range, clipping starts to occur ( "Clipping" refers to a situation where the power generated by the solar panels exceeds the inverter's ability to convert it into usable electricity. When this happens, the inverter must reduce the input power to avoid overloading the system. As a result, some of the energy produced by the solar panels is lost. Clipping can reduce overall system efficiency. It is therefore important to correctly size the inverter to prevent this from happening).