Mc4 connectors

[Szabie]

Was just wondering is ther a limit to how many panels you can join up in parellel using mc4 Y branch connectors before using a combiner box

[Raj]

Current limit is determined by the size of the wire used. The more you have in parallel the higher the current.

[Szabie]

What's usually attached to solar panels I think it's 4ag

[Raj]

It's usually 12 awg, sometimes 10

[Szabie]

Sorry I thought it was a simple question

[Szabie]

Ok I believe it to be 6awg or 4 mm square

[B-17]

Two strings is usually the limit, because above that the individual strings need over current protection anyway. I have found the MidNite combiner boxes to be a good value and it helps keep all the wiring neat and indentfiable

[Szabie]

Ok thanks heaps I was just trying to make it easy for myself I have a heap of branch connectors but no combiner box the nearest shop is 400km away so all my new toys will have to wait cheers

[sensij]

Was just wondering is ther a limit to how many panels you can join up in parellel using mc4 Y branch connectors before using a combiner box

The limit is based on the current rating of the connectors, usually 20-30 A. If you combine more than two panels, you can still avoid a junction box if you put an mc4 inline fuse on each panel.

[B-17]

Yes, the inline fuses can be done but it can soon become a hornet's nest of ugly wiring, and then there's no good disconnect, no good string isolation for troubleshooting or upgrades... not to mention a good space for labeling etc.

[Szabie]

No probs was thinking I might make my own combiner box to save some coin ...would putting 2 bus bars +&- putting all cables in and having a 40amp breaker fuse between it and charge controller should work eh

[B-17]

Each string needs it's own breaker. By the time you have everything together the MidNite combiner looks like a relative bargain. Plus it already will pass inspection when wired correctly

[Szabie]

Ha ha didn't realise that I wonder if all them blokes on YouTube still have houses ... cheers b17 your advice has been invaluable

[Szabie]

Just watched a YouTube video of a guy from renogy which is supposed to be a good company using branch connectors to connect 4 strings together with no fuses ... now you guys are confusing me

[sensij]

Just watched a YouTube video of a guy from renogy which is supposed to be a good company using branch connectors to connect 4 strings together with no fuses ... now you guys are confusing me

Again, it depends on the current. If you are talking about panels with an Isc of 5 A, four in parallel through those branch connectors is probably fine (with in-line fuses), maybe five. Isc of 9 A, definitely not.

No fuses with more than two parallel panels is a bad idea, not compliant with the panel's installation instructions or any applicable code.