MPP voltage range of the inverter and   the max. allowed voltage of the inverter, Both values have to be referred to the building site and the environmental conditions. Main conditions to be considered is the ambient temperature and sometimes wind conditions which may influence the cell temperature remarkably.

Exception: Should the reverse current availability (RCA) be mentioned but without fuse data, for a parallel connection of strings it is recommended that the sum of strings should not exceed approx. 60% of the allowed reverse current value.

Example:        RCA of a module = 25A

       Isc module = 6 A

       Strings in parallel:   4 (= RCA 100%)

       corrected no. of strings = 3

       (= RCA 72%), approx. 28% safety factor < 60%