Solar panel fusing

[Matlock]

When I installed my first 2 100 watt panels I went with a 30A fuse before the controller based upon suggestions here and knowing I was going to be adding another 2 panels later on, so that fuse worked as an on-off switch allowing me to safely work on panel wiring and tap in for even more portable panels later. I used 10 AWG from the panels to the fuse, 6 AWG to the controller, and 4 AWG to the batteries. Also, I liked what windy nation and other manufacturers offered as a diagram when I first started investigating how I would set-up my system.


This is the breaker I use.
https://www.amazon.com/ZOOKOTO-Circ...aker&qid=1554902444&s=automotive&sr=1-2-spell

just my 2¢

 

[Seminole Wind]

Then why do so many makers and sellers of solar panels and controllers recommend them?

because the makers and sellers KNOW what they are talking about.

here are a pair of decent articles explaing the situations that can arise and how to properly protect a system



https://www.civicsolar.com/support/installer/articles/when-fuse-when-not-fuse

https://www.windynation.com/jzv/inf/how-properly-fuse-solar-pv-system

if someone wants to disregard the specs and regs, that is on them. but to post here and tell people, that are looking for the right way to do it, to disregard the specs and regs is just wrong

 

[B and C]

From the Windy Nation linked above.

"Solar Panel fusing
Commercially made solar panels over 50 watts have 10 gauge wires capable of handling up to 30 amps of current flow. If you connect these panels in series, there will be no increase in current flow so fusing is not required for this string. This is not the case when you have panels connected in parallel, as when connected in parallel the system current is additive. For instance if you have 4 panels each capable of up to 15 amps, then a short in one panel can draw all 60 amps towards that short-circuited panel. This will cause the wires leading to that panel to far exceed 30 amps causing that wire-pair to potentially catch fire. In the case of panels in parallel, a 30-amp fuse is required for each panel. If your panels are smaller than 50 watts, and use only 12 gauge wires, and 20 amp fuses are required."

It all depends on the panels , wire sizes and configuration.

 

[AJ452]

But don't modern panels have diodes these days that prevent current going back toward the panel or something like that?

 

[Seminole Wind]

But don't modern panels have diodes these days that prevent current going back toward the panel or something like that?

the blocking diodes are only intended to prevent current/power loss to to re radiation at night which is a tiny amount of power. if enough power is put to them in reverse polarity they can and will toast easily. bypass diodes are different but are still only rated for so much. when you apply more power from more panels things can go amiss


why is it so hard for people to just accept that the manufactures know what they are talking about with fuse protection.

sure you might get away with it, but why gamble. it is a simple matter to read the specs for what ever panel you are using and follow those recommendation. if you dont want to run fuses then assemble them in strings that dont require extra fuses.

that is what i did for all 2000 some odd watts i have

 

[Weight]

You win! Your watt is bigger than mine.

 

[Seminole Wind]

ya, and i did it without fuses (on the panel wires) by using multiple controllers and keeping the strings of panels withing the specs and regs

and a little creative mounting to get all that on a 20' skoolie...