Need Help

[zerzuri]

Hi!

I need your help!
I have four 240w Trina solar panels wired in 2s2p configuration. Voc 37.2 and Lsc 8.37. These panels are connected to my Epever 30 amp MPPT Charge controller Tracer3215BN for a 24v system. I have installed a 20amp DC breaker for solar panels to the charge controller and installed a 30amp inline fuse between the charge controller and the batteries. Based on the charge controller’s specs the max wattage for the charge controller is 780w. However, if I remember correctly, while talking about sizing diy solar system in one of his videos Will mentioned that we can over panel these charge controllers. So my solar panels are 960w (4x240). Today after I came from work I found that the charge controller was off and with a quick inspection I found out that the inline fuse between the charge controller and batteries was blown. MMPT Charge controller must have produced produce more than 30 amp. But I don’t know what size fuse I should put now to be safe and not to frequently blew a fuse.

Will you please help me what size of fuse should I install between the charge controller and the battery so the fuse does not blow.

Thanks

 

[sunshine_eggo]

Your over-paneled controller likely ran at 30A for an extended period whereas with a proper/under-sized array you would infrequently hit 30A.

Fuses/breakers run at their rating will blow/pop.

Fuses/breakers should be sized 1.25X the wire rating. So you should have 10awg wire or thicker for 30A and a 37.5A (round up to 40A) fuse/breaker.

 

[400bird]

I've never liked that style of fuse holder. See how the entire thing is melted? If I had to guess, that fuse holder was probably part of the problem.

Also, fuses don't do great running at their rated current for long periods, it creates lots of heat. I'd recommend upping the fuse one size (and wire gauge accordingly)

 

[400bird]

Dang it! Yeah, what Eggo said

 

[sunshine_eggo]

Dang it! Yeah, what Eggo said

Good catch on the fuse holder. I'm getting too lazy to click pictures in my old age...

 

[zerzuri]

Thank you all! I really appreciate your prompt responses.
As sunshine_eggo suggested I rewired the controller to the battery with 10awg wire (actually I put two 10awg) and installed a 40 amp DC circuit breaker.

Thanks again for your support!