String fuses

[JulianC]

The (desparately in need of an update to reflect current technological advancements imo) DTI guide to the installation of PV systems states the requirement for string fuses when there are 4 or more parallel connected strings. What if I take these 4 strings and connect them to an inverter with, say, 2 MPP tracker inputs, and split the strings up over the 2 inputs, either as 3-1 or 2-2? Do I still need string fuses? Given that the fuses are necessary to prevent a shorted string from taking the full short circuit current from the other strings it is paralleled with, surely splitting the strings over more than one MPP input effectively separates them so that they are no longer parallel strings as such?

Your thoughts on this would be appreciated as I will try anything to avoid the expense and hassle of dozens of fuses and some fancy (expensive) monitoring equipment

Ta and Merry Christmas.

 

[SolarCity]

I'd assume this would effectively mean there are 2 strings per MPP input so would negate the need for the fuses. It'd be worth speaking to the inverter manufacturer to make sure.

 

[Markc]

I agree in these circumstances where is the possible threat of the increased short circuit current? All be it string fuses are not a top dollar items but the reason for fitting them is not possible in the circumstances you posted.

Saying that like a lot of issues with this industry at the moment is it not best to fit them and be damned for doing so over not fitting them and being damned for not doing so?