As solar-integrated residential electric vehicle (EV) chargers become increasingly common — driven by rising energy prices, grid constraints, and decarbonization efforts — evaluating their real-world performance is becoming essential. Laboratory testing, based on a guideline developed by the German research institutions Fraunhofer ISE and HTW Berlin (University of Applied Sciences Berlin), the German automobile association ADAC, and an industrial council, has shown a wide range of results for factors such as control behavior, standby power consumption, and control accuracy. While these measurements offer valuable insights for researchers and engineers, they are often too technical for end users. Therefore, a unified performance indicator is desirable.

This paper proposes a simulation-based performance indicator for residential solar-optimized EV chargers, inspired by established metrics used for PV battery systems. The methodology for evaluation includes: (1) measurement according to the guideline; (2) importing representative input data and parameterizing the simulation model; (3) simulating both an ideal and a real charger using laboratory measurement data; and (4) comparing grid consumption and feed-in values to express the charger’s performance as a percentage of the ideal benchmark.

By building on detailed laboratory results, the simulation model combines accuracy regarding key features with the scalability of analyzing longer time series. The proposed indicator enables more transparent product comparison and informed decision-making for stakeholders. Initial findings show that some chargers achieve only 75% and 92% of the performance of an ideal system under identical conditions, revealing considerable potential for optimization. This contribution presents the methodology and introduces a novel metric that highlights, for the first time, significant efficiency differences among commercially available residential EV chargers.