Help on Small Home Dual MPPT Controller 24v Installation Please

[littlehuw]

Hello all, thankful to have found this forum!
A bit of background, originally had done solar on RVs and wanted to carry that through to power the garden pond and garden lights.
That worked, and then included the washing machine and now looking to add the fridge and freezers on.
I get there are limits on expandability and we are most definitely nearing ours which would mean going to a 48v system.
So where are we at. We have just got 2 x 375 panels and have purchased a second MPPT controller - see attached schematic.
Epever say they wont work together as they both have to be minimum 60A controllers to use their parrallel adapter.
Nick Seghers in his Off Grid Solar Power Simplified book says that they don't have to talk to each other to be able to work.
I also got a bit confused with how these then go into the battery breaker so have order two different ones as per the charge controllers.
So Question 1 Do I need the 2 Breakers or will both chargers go into the one and will that be the lower or the higher amp?
The battery people told me when asked about best power rating for the batteries to set at 56A or minimum 10% power for the inverter/charger (currently dumbed down to 42A on AC as it kept drawing too much and blowing the fuse, more about how its connected into the house I think!)
Question 2 Is there a setting to set the chargers to the same output amps or the maximum?
Question 3 Is there anything else I am missing?
Schematic doesn't show the earthing rod and cable which I am installing tomorrow before I faff with anything else. It has been very much a grow and learn and so far I've only blown up one 500w inverter!!! Currently the set up is first string of 2 x 375w and second string of 3 x 150w which we now know is over the capacity of the 40A controller but it didn't get installed until September last year so thankfully hasn't maxed it out. The 4 x 220ah batteries are set to 24v in series so hopefully giving us 2400watt hours. At the moment through the winter, the AC charger has kicked in during the night with very minimal draw on the battery side of things.
Anyhoo, will probably have more questions as the thread progresses.
Cheers for any help, gratefully received. Huw

 

[Mattb4]

1. Use two breakers, one for each SCC output, each one with the amps it is expected to carry. Your wire needs to be sufficient sized also.
2. Set the charge profiles on each SCC such that one is at a slightly higher charge (normal charge) voltage than the other. The idea is to have both producing when battery is low enough to accept total current from the 2 SCC's but have one drop off before full charge. You do not need to match amps and a lot of SCC have no ampearage control other than CC, CV.
3. Hard to say.

 

[littlehuw]

Thanks Mattb4. I had also forgotten to include a breaker between the battery and the inverter of 180A!
Question. Can the charge controllers go from their respective fuses straight to the battery on a separate bolt or should they be combined on a busbar so only one cable is going to the battery? I am guessing that because they are both reading the battery voltages that they would be ok to continue the wire separately. Similar with negative wire? Am using 16mm cable to the battery.
Cheers, Huw

 

[Symbioquine]

Thanks Mattb4. I had also forgotten to include a breaker between the battery and the inverter of 180A!
Question. Can the charge controllers go from their respective fuses straight to the battery on a separate bolt or should they be combined on a busbar so only one cable is going to the battery? I am guessing that because they are both reading the battery voltages that they would be ok to continue the wire separately. Similar with negative wire? Am using 16mm cable to the battery.
Cheers, Huw

It doesn't matter how they're connected to the battery/batteries from the perspective of the charge controllers - except obvious things like getting the polarity right and that each should have its own fuse/breaker as previously discussed. (There is also a different topic regarding how batteries should be connected to ensure they equally share the load/charge current, but I'm assuming you're not asking about that. If you are, see Section 3.3 of https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf .)

Some charge controllers do have a separate voltage sense wire that does need to go separately to the batteries, but if you don't have that you can ignore it.