How do solar panels affect the short circuit fault currents of a network?
Looking at the solar panel characteristics, you will see that the short-circuit current of the panel is not much above the current at the maximum power point. The inverter will probably have capacitors on the DC side to accommodate the reactive volt-ampere demand of the load. The stored energy in those capacitors could contribute to the prospective short-circuit current, but the current level would be limited electronically by the inverter. If the inverter fails, it would not be able to supply current to a short-circuit on the AC side. It might represent an additional short circuit path carrying current supplied by the solar panel.

With respect to the comment, prospective fault current that is very much above 1 PU would be electronically limited. Any failure of the electronic limit would essentially create another short-circuit path. The capacitors would be like a spinning mass, but isolated from the distribution system by the inverter.