diy solar

diy solar

DC fuse caught fire! Help ?

My inverter is EASUN SMG II.. it is supposed to be able to run batteryless with a PV voltage above 200V. The input mppt is 150 to 450 volt.

I checked continuity between the pv inputs on AIO and its fine.

Ofcourse I didnt connect the pv modules to the battery inputs or the battery to pv input.

I have batteries on hand and the AiO works fine with the batteries.

Link to inverter
https://easunpower.com/products/eas...vdc-input-batteryless-support-with-wifi-pllug

link to panel

 
EliteSolar said:
My inverter is EASUN SMG II.. it is supposed to be able to run batteryless with a PV voltage above 200V. The input mppt is 150 to 450 volt.

I checked continuity between the pv inputs on AIO and its fine.

Ofcourse I didnt connect the pv modules to the battery inputs or the battery to pv input.

I have batteries on hand and the AiO works fine with the batteries.

Link to inverter
https://easunpower.com/products/eas...vdc-input-batteryless-support-with-wifi-pllug

link to panel

Click to expand...
Good. Simple mistakes can lead to big problems. Now you just need to find the cause of excess current flow causing your fuse holder to melt.
 
The fuse itself is good for the voltage of your PV array, and probably won't blow with the current.
(I think 12A fuse is smaller than the recommended minimum 1.56 x Isc; what are ratings on PV panel label?)

The fuse holder is touch-safe, but not meant to open or close with load.
If closing the fuse holder shorts the PV string, then fuse to fuse holder contacts would burn under load.
If wire connection isn't good, that would heat up.

If PV string is wired reverse-polarity, it hopefully has protection diode, but that makes a short circuit.

You should check voltage across fuse holder with DMM before closing. If that completes circuit to inverter, capacitor would take forever to charge up through 10 meg ohm DMM, looks like a short. In that case, a precharge resistor scheme might be advisable. I have fuse and switch. DMM briefly shows voltage across switch just charging capacitance of wire. I check polarity with DMM, then close switch.
 
The ratings for LSC is 11.07A and my fuse is 12A. It was the only I could find locally, all the others were lower amp , or else I would get a 15A one

Sure Ill post a pic of the burnt one now

paint6.jpg

I always try to take safety measures and do it in a proper space
 
Last edited:
EliteSolar said:
Hi All!

So I'm kinda new , I have 8 panels 320V ( 3.1kw ) in series open circuit voltage and a AIO 3.6kw inverter.

So I got these DC fuses to install between the panels and the inverter.

I checked with the multimeter that the polarity was good and when I closed both + - circuit fuses I was reading 0v and then when I tried again one of the caught fire!

I read about the current flow that it has to enter in a specific way for DC breakers but mine is just a fuse and it doesnt mention current flow diagram ? Or I don't understand.

Should have I connected the panels on top of the fuse ? Or is something else is happening ?

I tried to turn on the inverter with just battery and it works fine it seems. Is there any possibility I have destroyed something in the panels or the inverter ?

Thank you!

Edit : The housing is made in france and the fuse made in italy. Shall I get a circuit switch breaker instead of fuse ? Im going to the shop again to buy new
View attachment 114362View attachment 114361
Click to expand...

I tried fuses, and housing similar to what you have. Mine got scary hot, and when I started smelling plastic melting I shut it down.

I switched to midnight breakers. I wont do the fuses ever again.
 
BradCagle said:
I tried fuses, and housing similar to what you have. Mine got scary hot, and when I started smelling plastic melting I shut it down.

I switched to midnight breakers. I wont do the fuses ever again.
Click to expand...

Just carrying current, not arc on closing?
Any chance it was wire to terminal, or do you think it was clip contact to fuse?
What fraction of rated current?

I had a box full, but carrying 7A through 15A fuse in each 30A holder.
Power dissipated proportional to I^2R, so 1/4 rated self-heating of fuse, 1/16 rating for fuse holder. very benign.

OP's 12A fuse in 32A holder, with ~ 10A to 12A panel, could have made fuse hot (normal rated temperature) but holder should have been fine.
 
Hedges said:
The fuse itself is good for the voltage of your PV array, and probably won't blow with the current.
(I think 12A fuse is smaller than the recommended minimum 1.56 x Isc; what are ratings on PV panel label?)

The fuse holder is touch-safe, but not meant to open or close with load.
If closing the fuse holder shorts the PV string, then fuse to fuse holder contacts would burn under load.
If wire connection isn't good, that would heat up.

If PV string is wired reverse-polarity, it hopefully has protection diode, but that makes a short circuit.

You should check voltage across fuse holder with DMM before closing. If that completes circuit to inverter, capacitor would take forever to charge up through 10 meg ohm DMM, looks like a short. In that case, a precharge resistor scheme might be advisable. I have fuse and switch. DMM briefly shows voltage across switch just charging capacitance of wire. I check polarity with DMM, then close switch.
Click to expand...

Hi , as I said my LSC is 11.07A and LMP 10.57 and my fuse is 12amp , I know not ideal, but doesnt explain the problems I have, does it ? I am not having any load on the AC output , I just want to power the inverter for start.

So what you say , that if the fuse holder shorts the PV string , that explains why it didnt burn last night at sunset, it was quite dark ( I had like 250V ? instead of 330V ~ ) and the voltage drop stayed at 0, as I explained before , but burnt today when there was full sun ( it was around 330V I think when it burnt ) ?

I checked with the multimeter that my positive and negative are correct.

I tried to find switches but DC not available. So the only way to close the circuit is to close the fuse , or connect the mc4 cables ( or connect directly to inverter ( I would never do that for safety reasons ) .

When I closed both fuses voltage dropped to zero before or after the fuse. 2nd time I tried it after I checked all my cables , one fuse holder caught on fire .

So the problem really is why is the inverter shorting the PV array ?

Thank you all for your responses I highly appreciate it because I can't get anyone near me to help me with my setup. And I also love to learn new things ( without dying hopefully :) )
 
Last edited:
First time I've seen a fuse that can be opened and closed like a breaker used in solar, I thought it's only a thing from very old AC panels.
 
Looking at the picture of the burnt fuse holder it makes me wonder if you have the right fuses installed. There is definite indication of arcing which would only happen if solid connection was not being made. Did the fuse blow?
 
I have no way of telling since the plastic has melted and I cannot extract the fuse from within the holder.

Shall I try to break it to see if the fuse blew ? Does it matter ? Would that mean Im using the wrong fuses ? Why would it drop to zero at night before it blew and stay like that ?

The fuses are the ones I showed in the first post.
 
Last edited:
EliteSolar said:
I have no way of telling since the plastic has melted and I cannot extract the fuse from within the holder.

Shall I try to break it to see if the fuse blew ? Does it matter ?

The fuses are the ones I showed in the first post.
Click to expand...
It matters if the fuse did not blow because it would indicate that it was not excessive current enough to blow fuse (short circuit condition). Arcing that can happen due to a bad connection creates heat that eventually damages things. It is like a loose wire at a terminal gets things hot eventually.

The fuses shown and the holder must match and I can not tell from your pictures if they do.
 
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