Fusing small panels.

[Short_Shot]

I have 2x 20w and 1x 10w panels on my tongue box. This was done due to the odd size of the lid resulting in overhanging of a single 50w panel. Currently there are no fuses on any of them.

Of course this means low fuse ratings are required. So I started looking...

Are fuses even needed since I've got diodes installed on each panel which are rated for much more than the total output of the other panels (20a)?
Seems to me like this would entirely prevent current flowing through any potentially shorted panel since it's all DC.


The 20w panels have an operating current rating of 1.16a and short current is 1.23a.

The 10w panel operating current is 0.63a and short current rating is 0.66a.

Should I fuse the 20w panels at 1200ma and 10w at 650ma or will I just be popping fuses randomly due to them being so close to the rated limit?

Are fuses in these current ratings even available for the typical MC4 solar fuse holder?? If not I can just get a different kind of fuse holder no problem.

 

[newbostonconst]

Not needed. I think in this situation you would only install fuses if the panel or inverter manufacturer required it in their documentation.

 

[Short_Shot]

Not needed. I think in this situation you would only install fuses if the panel or inverter manufacturer required it in their documentation.

Well.


NEC says as long as the total current of the panels exceeds the fuse rated current of any one panel then fuses are in fact required.

That is the case here even if the current involved is so low, especially if I attach my suitcase panel which itself is 100w. This connection is done in parallel with the other 3.

Now I'm cool with ignoring NEC since this system is my responsibility, but I'd still like it to be as fault tolerant as possible.

I keep coming back to the idea that the diodes will prevent fault current from flowing back through a shorted panel but without being able to easily test this I'd just like confirmation.