I did not put a fuse on my solar panels because I believed my Airstream's electrical diagram in the owner's manual that stated there was a fuse installed. When I researched the Zamp Rooftop Box that is installed on my Airstream, the descriptions said there was a 40A fuse installed. Here is a marketing picture of the Zamp rooftop box showing the fuse installed: https://www.rvupgradestore.com/3-Por...-p/19-2768.htm
I believe Uncle_Bob added a fourth SAE port to his and said there was a 40A fuse. But recently, Kalashnikov had a problem with his prewire so he removed his Zamp rooftop box and there was no fuse installed. Therefore, I do not know how to answer this question. I continue to use my rooftop box with the assumption there is a 40A fuse inside.
2018 GT27Q, 73 nights 12,177 miles, 600W Solar - 110kWh, PD4655L, 6V Batteries, Blue Ox, 16" tires, 2019 F250 PSD
Sold: 2017 FC25FB, 316 nights 40,150 miles, Propride, 400W Solar - 200kWh in 216 days
2013 Casita SD17 89 nights 16,200 miles