Investigating the Effect of Power Curtailment on the Switch of a Solar Boost Converter Under Residential Loads

Abstract

The massive deployment of PV systems in residential buildings is causing voltage challenges in low-voltage distribution networks. Worldwide, DSOs started requesting users to curtail power when this is injected back into the grid. Although many commercially available inverters can perform curtailment, the degradation effects of curtailment still have to be investigated. This paper estimated how power curtailment affects the reliability of a boost converter working below MPPT voltages. Using the mission profile method, we determined the conduction and switching losses on the converter switch as the critical component, based on its temperature and current profiles. The results suggest that curtailing the power requires the operation point to move towards lower PV voltages, leading to deeper thermal cycles, therefore reducing the expected lifetime of the converter by up to 80 % for power injection into the grid below 1.5 kW. From the operational perspective, this might require premature replacements compared to operating under MPP conditions, affecting the revenue forecast before the enforcement of curtailment. For power injection above 1.5 kW, the LCoE does not change compared to the case without considering the degradation. However, near zero-injection conditions, the difference in LCoE between considering and not considering replacements increases exponentially up to 135 %.