Tuv standard for photovoltaic combiner boxes

If the PV junction box is intended to be used with several types and/or combinations of bypass diode and/ or with several rated currents of the PV junction box, the tests must be performed in all possible combinations with the relevant number of specimens. Another consideration is whether or not the PV junction box is potted.

For rewirable connections of the conductors in the relevant terminals, sufficient volume inside the PV junction box must be provided to avoid any damage to the cable and to ensure adequate termination of the cable. In contrast to UL standards or specifications, no particular volume depending on the cross-section of the cables is stipulated.

No water must enter the PV junction box. This requirement will be checked by the r.m.s. withstand voltage test using a voltage of 2000V + 4 × rated voltage, applied between a metal foil covering the enclosure and the connected cables of both polarities. After the IP test, a wet leakage current test has to be performed.

This is followed by the test sequence of test group D, to check retention of the PV junction box on the mounting surface, and then the wet leakage current test. The fixing of the lid is also tested after the damp heat pre-treatment. The specimen has to be prepared in the same manner as in test sequences I and II.

Of course, box can be performed according to if a PV junction box is to be tested in European standard EN 50548 and to combination with a PV module, the tests national documents such as DIN V can be performed on the complete sample. VDE V 0126-5 or UL-subject 3703.

If a manufacturer changes materials, construction, rated values, etc. then the conformance of a PV junction box to a standard must be reassessed. Although a retest does not always have to be carried out, most modifications will require it.