SOLAR PANELS REVERSE CURRENT ISSUES
Green Power operate a dedicated solar service and maintenance division, which often finds electrical faults in PV systems. In some circumstances, these electrical faults in solar panels lead to current being forced in the wrong direction through a string of PV modules. All solar PV panels are designed to withstand a certain degree of reverse current without damage occurring to the modules. For Q CELLS, this protection allows for up to 20A reverse current. For most other panels, this protection is only up to 15A.
So what does this mean in the real world?
When solar panel strings are connected in parallel, Australian Standards AS 5033 requires over current protection if the reverse current protection of each single string is less than the current generated by the remaining strings.
In the illustrated example below, a fault has occurred which has resulted in current from Strings 2 & 3 being fed into String 1. In this instance, no over-current protection is required for Q CELLS panels, as the reverse current protection (20A) is greater than the maximum current generated by the remaining strings (total 17.8A). However, if the reverse current protection was only 15A (as is the case for most other panels), a reverse current protection device would be required on all three strings. This is a requirement of AS5033:2014.