For Europe, HD 60364 Part 7-712 prescribes the following: PV fuses must be used in photovoltaic systems where more than two PV strings connected in parallel are installed per MPP tracker. This requirement applies because photovoltaic installations ha...
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For Europe, HD 60364 Part 7-712 prescribes the following: PV fuses must be used in photovoltaic systems where more than two PV strings connected in parallel are installed per MPP tracker. This requirement applies because photovoltaic installations have to be short-circuit-proof.
In photovoltaic systems, the short-circuit current is almost in the nominal operating range. With one or two PV strings, the PV fuses do not have a protective function and even impair the system performance as they represent a potential source of error and also cause a slightly higher power dissipation.
With three or more PV strings connected in parallel, PV panels can be destroyed in the event of a double insulation fault due to a residual current or PV cables can be subjected to loads outside their nominal operating values. In this case, PV fuses make an important contribution to protecting the photovoltaic system and preventing downstream personal injury and damage to buildings.
The manufacturer’s data sheet provides information on the reverse current capacity of PV panels and the maximum fuse protection required for them.
Photovoltaic systems with DC power optimizers (e.g., from SolarEdge) are an exception. In some cases, power optimizers with up to three PV strings connected in parallel can prevent residual currents in the PV cables or PV panels. In this case, the use of PV fuses can be avoided. Please also observe the information provided by the power optimizer manufacturer.
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