N.J.C.M. van der Borg

Recent test results of 6 commercial inverters for grid connected PV systems

Test results of 6 commercial inverters for grid connected PV systems in the power range up to 5 kW are given. The considered aspects include: energy efficiency, power point tracking efficiency, start-up power, power quality, conformity to EMC standards, acoustic noise and susceptibility to electromagnetic noise. The results are obtained with the PV test facility of ECN. The results show that in the last few years considerable progress has been made concerning the performance of grid connected inverters which are available on the European market. In general the efficiency is over 88% over a wide power range, with a peak efficiency of about 92%. Most inverters comply with standards concerning power factor, harmonics, EMC and acoustic noise.

Accuracy of Energy Prediction Methodologies

In the current market, the specific annual energy yield (kWh/kWp) of a PV system is gaining in importance due to its direct link to the financial returns for possible investors who typically demand an accuracy of 5% in this prediction. This paper focuses on the energy prediction of photovoltaic modules themselves, as there have been significant advances achieved with module technologies which affect the device physics in a way that might force the revisiting of device modelling. The paper reports the results of a round robin based evaluation of European modelling methodologies. The results indicate that the error in predicting energy yield for the same module at different locations was within 5% for most of the methodologies. However, this error increased significantly if the nominal nameplate rating is used in the characterization stage. For similar modules at the same location the uncertainties were much larger due to module-module variations