Trying to understand stuff after a foolish mistake

[Jonathan123]

My panels each carry a IMP of 9.8 amps so apparently I’ve got 40 amps incoming.

 

[Jonathan123]

@Mattb4 I’m seeing 60 amp circuit breakers available and the general recommendation for between scc and battery seems to be to size according to the scc. Would a 60 amp breaker be appropriate?

 

[mikefitz]

10 AWG cable has a maximum current rating and it seems from the picture this is being used for cables to the solar panels and to the battery. At the maximum I expect that cable to be rated at 50 amps, typically around 30 to 40 amps.

Would a 60 amp breaker be appropriate

The over current protection, fuse or breaker, has to protect the cable and stuff on the end of that cable from the high energy source, the battery.
In adition to the current safe capacity of the cable in a 12v system , volt drops need to be considered.
For 3 feet of 10 AWG in a circuit between battery and controller the voltdrop will be about 0.36 volts. The fact that the controller will 'see' a voltage higher than the actual battery voltage may compromise the charging process. Some volt drop will always occur but the cable selection should be made to minimise this.

There will also be volt drops on the solar side but these are less of an issue.

Summary,
a) your solar array and cable to the controller need reviewing to check that you are not exceeding the current rating of the cable and connections.
b) the cables between controller and battery are unsuitable and need to be upgraded and protected by a suitable fuse or breaker.

 

[Mattb4]

@Mattb4 I’m seeing 60 amp circuit breakers available and the general recommendation for between scc and battery seems to be to size according to the scc. Would a 60 amp breaker be appropriate?

A 63a breaker (more common in DC than 60a) would work but not ideal. You would want to watch for heating and nuisance trips. Your cable should be 6 awg depending on cable type and length between battery and controller. The subject is discussed here: https://battlebornbatteries.com/battery-cable-size/

Edit: Might ought to begin from the beginning and look at your full panel ratings for voltage, current and SCC specs. The planned setup such as panel arrangement, parallel or series, disconnects and fuses, distance from SCC, battery specifications and also what your are powering (loads) all of this with. The fact they shipped you 10awg wire does not mean that it is appropriate for all setups and they likely never intended it to be used for the battery side of things.

 

[Wattsinwattsout]

You may be limited to the cable size by the controller bus connection. Some of these won’t allow 4-6 gauge wire to be inserted. If you can only insert 8 gauge wire then size your beaker/fuse accordingly. If panels are maxed out at 40 amps but the voltage is higher than 12v the SCC will convert the extra voltage to more amps at 12v. It can be more than 40 amps?

You may be limited to 8awg wire with that controller connection.

 

[Jonathan123]

10 AWG cable has a maximum current rating and it seems from the picture this is being used for cables to the solar panels and to the battery. At the maximum I expect that cable to be rated at 50 amps, typically around 30 to 40 amps. The over current protection, fuse or breaker, has to protect the cable and stuff on the end of that cable from the high energy source, the battery. In adition to the current safe capacity of the cable in a 12v system , volt drops need to be considered. For 3 feet of 10 AWG in a circuit between battery and controller the voltdrop will be about 0.36 volts. The fact that the controller will 'see' a voltage higher than the actual battery voltage may compromise the charging process. Some volt drop will always occur but the cable selection should be made to minimise this. There will also be volt drops on the solar side but these are less of an issue. Summary, a) your solar array and cable to the controller need reviewing to check that you are not exceeding the current rating of the cable and connections. b) the cables between controller and battery are unsuitable and need to be upgraded and protected by a suitable fuse or breaker.

Thank you! Just picked up 4 gauge cables to replace the 10 gauge between controller and battery and ordered a 60 amp breaker. From what I can tell that is the correct size breaker but please weigh in if that’s wrong.

 

[Jonathan123]

A 63a breaker (more common in DC than 60a) would work but not ideal. You would want to watch for heating and nuisance trips. Your cable should be 6 awg depending on cable type and length between battery and controller. The subject is discussed here: https://battlebornbatteries.com/battery-cable-size/

Edit: Might ought to begin from the beginning and look at your full panel ratings for voltage, current and SCC specs. The planned setup such as panel arrangement, parallel or series, disconnects and fuses, distance from SCC, battery specifications and also what your are powering (loads) all of this with. The fact they shipped you 10awg wire does not mean that it is appropriate for all setups and they likely never intended it to be used for the battery side of things.

The 10 gauge was explicitly intended for the controller to battery connection. However I notice this same kit being sold on Rich Solar now comes with 4 gauge for that purpose.

 

[Jonathan123]

I found a local electrician to come out in a few weeks and review my whole system.

 

[Jonathan123]

Thank you all for your help with this. Much appreciated.

 

[Mattb4]

The 10 gauge was explicitly intended for the controller to battery connection. However I notice this same kit being sold on Rich Solar now comes with 4 gauge for that purpose.

Somebody dropped the ball on that one. 4 gauge is much more appropriate for a 60 amp SCC.