Breaker size

[Revid]

Got my system almost done except for a breaker between my solar panels and mppt. Iam attaching a pic of my wiring and a pic from bk of panels . Could someone tell / show me the total numbers( amps and volts) and a suitable size of breaker? I don’t know which numbers to use from bk of panels. Most videos use different abbreviations and it’s totally confusing. Thanks

 

[WrenchLight]

Usually people install fuses on the solar strings instead of breakers. The midget size (10x38mm) 20A / 690V or 1000V fuse is a common choice.

 

[Revid]

Iam using 10 awg wire from panels to mmpt so do I size breaker to wire? 10 awg is good for 30 amps so all I can find is 24 and 40 so guessing I would go with 25??

 

[Robert Ibe]

You have 1 string of panels in series , your Isc ls 13.93A , your maximum series fuse rating is 25A , you have a disconnect switch from your panels to your scc so you have the disconnect covered. A breaker (or fuse) would serve no purpose. You would not need a breaker (or fuses) .

There are a number of sites and videos out there that can explain when and how to fuse/breaker solar panel arrays better than I can here.

 

[Revid]

Thanks Robert, my mistake. The switch you see from panels to scc is what Iam trying to replace, actually it’s not even installed it. I was going to use it but the bolts are to big (3/8”)and I only have #10 wire coming from panels so I can’t find a lug to fit wire and bolt at same time. So I thought I would fit a breaker there instead

 

[MisterSandals]

So I thought I would fit a breaker there instead

Do you have a DC breaker already? Its not uncommon to use a breaker as a seldom used switch for solar.

 

[Robert Ibe]

Thanks Robert, my mistake. The switch you see from panels to scc is what Iam trying to replace, actually it’s not even installed it. I was going to use it but the bolts are to big (3/8”)and I only have #10 wire coming from panels so I can’t find a lug to fit wire and bolt at same time. So I thought I would fit a breaker there instead

Got it I saw the switch and misunderstood . I am using an IMO si32 PEL64R 4 Enclosed DC Disconnect Switch for 2 sets of 5s2p hyundai 300 watt panels (196.15 voc , 19.54 Isc total each set ) the IMO switch has Max. rated current of 32A@600VDC and is rated to be switched under load. it has 4 contacts so I can break + and - of both inputs. if you are staying with 1 string they make a 2 contact switch. IMO si32 PEL64R 2. they also make a 25A and 16A version just replace the 32 in the models I listed.

 

[Revid]

Yes will be staying with one string so by the sounds of it a 25 A breaker would be good. So my setup would be 4s1p? With the tag from panels above what would my total volts/ amps be? Iam still learning!

 

[Robert Ibe]

Yes will be staying with one string so by the sounds of it a 25 A breaker would be good. So my setup would be 4s1p? With the tag from panels above what would my total volts/ amps be? Iam still learning!

VOLTS . Multiply your voc x 4 for 4 panels in series and add 20% to be on the safe side as the voc goes up when the temprature goes down.
AMPS . Amps stay the same , Isc (13.93) 1 string in parallel = 1 x amps 2 strings 2 x amps , etc.

Not sure how bifacial panels effect the numbers as I am not familiar with them.