Procedure to carry out quality checks in photovoltaic grid-connected systems: Six cases of study

Assessing the correct operation of PV grid-connected systems (PVGCS) is paramount not only for mere energy and profitability concerns but also for safety reasons. Intended to this purpose, the IEC 62446 standard is open to some tests to be required in some circumstances, in addition to those stated in this document. Our work proposes a procedure to carry out quality checks in PVGCS complying with this standard and dealing with some tests not mentioned in it – namely, PV generator peak power measurement, inverter response and earth electrode measurement – so that the verification of the system gets more comprehensive. This procedure was carried out in six PV plants sited in different locations with a Mediterranean climate in Spain. The most remarkable results of this experimental campaign may be summarized as follows: an excellent on-site behavior of the inverters, in general very good figures for the isolation and earth electrode resistance and a scarcely relevant existence of hot spots. On the down side, some figures for the peak power of the tested PV generators well below their nominal value were found. The procedure described in this paper has proved to be a useful tool to assist in the verification of a PVGCS after installation and for subsequent re-inspection or maintenance.

Research highlights▸ Verifying correct operation-energy yield and safety- of PV plants: crucial issue. ▸ We propose a checking procedure that completes the existing IEC 62446 standard. ▸ PV generator peak power, inverter response and earth electrode are also measured. ▸ This procedure was carried out in six PV plants sited in Spain. ▸ PV plants pass the safety tests but some show a noticeable drop in their peak power