diy solar

diy solar

24v Solar Diagram for Trailer. Would love input!

ctc_ben

New Member
Joined
Feb 5, 2021
Messages
12
Here is my current diagram for my solar setup. I'd love any input on things that I'm missing, need improvement, and also parts that might be unnecessary. I'm still trying to decide between this and a growatt all in one 24v system. The only issue really being the noise.
 

Attachments

  • SolarDiagram.pdf
    940.7 KB · Views: 67
Put a DPST means of disconnect between the panels and the solar charge controller
Suggest an combined ac/dc "rv" style distribution panel

BMS needs to be able to handle 187.5 amps just for the inverter
You may be able to control your inverter via a solid state relay which is in turn controlled by the bms as an alternative.

3000 ac watts * 1.5 low frequency fudge factor / 24 volts = 187.5 dc amps
187.5 dc amps / .8 fuse headroom = ~234 fuse amps

Main fuse should be ~234 amps.
Class t fuse recommended.
 
Put a DPST means of disconnect between the panels and the solar charge controller
Suggest an combined ac/dc "rv" style distribution panel

BMS needs to be able to handle 187.5 amps just for the inverter
You may be able to control your inverter via a solid state relay which is in turn controlled by the bms as an alternative.

3000 ac watts * 1.5 low frequency fudge factor / 24 volts = 187.5 dc amps
187.5 dc amps / .8 fuse headroom = ~234 fuse amps

Main fuse should be ~234 amps.
Class t fuse recommended.
The main reason I went with 3000 watt inverter charger was that the availability of anything less than that is really limited. I don't actually need that much (Highest single output item is 1800 watts). I realize the BMS is specced a little low, so the idea was that the BMS would limit what I can actually use off the inverter. Taking this into account do you think it's fine? Thanks for all this advice, I appreciate it!
 
The main reason I went with 3000 watt inverter charger was that the availability of anything less than that is really limited. I don't actually need that much (Highest single output item is 1800 watts). I realize the BMS is specced a little low, so the idea was that the BMS would limit what I can actually use off the inverter. Taking this into account do you think it's fine? Thanks for all this advice, I appreciate it!
Sorry, I can't say its fine.
The workaround is to use drive the inverter/charger via a solid state relay.
Here is a video that demonstrates the concept
I can help with the real world implementation.

Also there are a good selection of 2000 watt inverter/chargers.
Even from Singineer who appear to be the manufacturer of the inverter/charger in your diagram.
 
I stand corrected sigineer is no longer making a 2000 watt inverter at 24 volts.
 
I stand corrected sigineer is no longer making a 2000 watt inverter at 24 volts.
Bummer. So I can understand the issue better, what happens if the BMS is undersized? Will it limit the inverter, or burnout the BMS and battery bank?
 
Bummer. So I can understand the issue better, what happens if the BMS is undersized? Will it limit the inverter, or burnout the BMS and battery bank?
The bms fets will likely fail closed.
That means it appears to work until it fails to disconnect the battery from the system when you really need it to.
You could wire 2 BMSs in parallel to the same bank and have them split the load.
Or you could use a contactor.
 
If you use the ssr you need to make sure that the inverter/charger doesn't charge when its turned off via the remote-control(ssr).
 
Is there a reason you wish to go with 24v, it does complicate things a bit more, most of your trailer runs off 12v without conversion.
 
Note that the 24-12V DC-DC converter leads are probably only 12 AWG. And the 40A is the output on the 12V side. 6 AWG wire is overkill and it's awkward connecting 6 AWG to 12 AWG. I have a 24V setup and use a nearly identical DC-DC converter. I kept the 12 AWG from the positive bus bar to the converter with a 30A ATO inline fuse on the positive lead. I added 10 AWG on the 12V output leads to the 12V fuse box. I kept all of those wires short - all under 2 feet. This all assumes you are using high quality, pure copper, 105ºC insulation wire.

Since you only show a 12V fuse box and not also a 24V fuse box, why are you setting up a 24V system? In my 24V system, I used as many 24V loads as possible such as the fridge, water pump, all of the LED lights, etc. I added a 12V fuse box with the converter for things that required 12V such as roof fans, 12V outlets, etc. But if you only have 12V loads, you can avoid the DC-DC converter and you probably have a lot more inverter options at 12V.
 
Back
Top