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Safety check my diagram so I don't blow up my wife and dogs please =) 400w solar, 2000w inverter, 50amp MPPT DCDC, 100amp fuse block

H

Helpmenotblowupmywife

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Joined
Mar 17, 2025
Messages
8
Location
Colorado
My attempt at following wills 400w DCDC set up, a little confused about the switches and fuses with correct wires cause renogy suggests smaller (higher AWG) than will so just wanted to see if this set up will work, I'm only missing the fuse to the car battery which I'm still trying to work out for a 2017 Promaster 2500.

Thanks a lot in advance, actually had a lot of fun trying to learn it all and play adult leggos.
 

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Hi. Welcome to the forum. You have some extra parts for sure.
  • For a smaller system, you don't need fuses on the solar panels going to the charge controller for example.
  • Your solar negative would not run to your ground busbar/block. Your charge controller will have a spot to connect PV + and -, along with battery + and -. Negative (-) in a solar system is not ran to a ground/ground wire.
  • You won't likely need 8 guage cable unless you are running a long ways with those panels.
  • You probably don't need busbars at all in this smaller setup, but you can use them. Could allow for adding more battery later.
What is MCH on your drawing after the panels?
If I were you, I would simplify it down a bit. Big systems get complex. Yours doesn't have to. Simple is also often safer. Less connections mean less places they could come loose, get hot, or get touched by something conductive.

People are pretty helpful here. Your best bet to get good advice is to list your actual parts you plan to use. That way the panel amperage, draw from the inverter, etc. can be discussed.
 
Last edited:
SunDave said:
Hi. Welcome to the forum. You have some extra parts for sure.
  • For a smaller system, you don't need fuses on the solar panels going to the charge controller for example.
  • Your solar negative would not run to your ground busbar/block. Your charge controller will have a spot to connect PV + and -, along with battery + and -. Negative (-) in a solar system is not ran to a ground/ground wire.
  • You won't likely need 8 guage cable unless you are running a long ways with those panels.
  • You probably don't need busbars at all in this smaller setup, but you can use them. Could allow for adding more battery later.
What is MCH on your drawing after the panels?
If I were you, I would simplify it down a bit. Big systems get complex. Yours doesn't have to. Simple is also often safer. Less connections mean less places they could come loose, get hot, or get touched by something conductive.

People are pretty helpful here. Your best bet to get good advice is to list your actual parts you plan to use. That way the panel amperage, draw from the inverter, etc. can be discussed.
Click to expand...
Hey thank you so much for responding it truly means a lot. The elimination of the mc4 fuse is helpful to know, i ultimately designed it in case we needed more solar to go up to 600w, the “MCH” is just the MC4 2:1 connector sorry about that.I have the renogy 50Mppt DCDC solar and alternator charger so it seems it doesn’t have a PV- and says to wire to battery/ground, i over did it on the wire so hopefully i don’t loose voltage if thats a thing? This was my serious attempt at a first draft and i can’t thank you enough for your feedback, thanks again i’ll keep working on it and revise
 
Helpmenotblowupmywife said:
I have the renogy 50Mppt DCDC solar and alternator charger so it seems it doesn’t have a PV- and says to wire to battery/ground
Click to expand...
I am not familiar with that type of setup. Maybe someone else who is will chime in.
Helpmenotblowupmywife said:
i over did it on the wire so hopefully i don’t loose voltage if thats a thing?
Click to expand...
It shouldn't hurt anything. Like you said, you wont lose any voltage. A fuse on the solar won't hurt anything either. It's just not required until you have more than two parallel strings of panels.

Good luck with your setup. If you read the manuals you should be just fine.
 
8AWG from your panels seems like overkill. What are your panel specs? 10AWG should be plenty with most 200W panels 2P.
What is your SCC max input voltage? If you can wire in series it can be wired simpler and lower amps.

Seems odd you are not wiring solar negative directly to the SCC. Any reason for that?

You show a 200A fuse to your 2000W inverter

2000W / 10V cutoff / .85 efficiency = 235A
You should wire and fuse for 250A or you will blow 200A fuses as you approach 2000W inverter loads.
 
MisterSandals said:
8AWG from your panels seems like overkill. What are your panel specs? 10AWG should be plenty with most 200W panels 2P.
What is your SCC max input voltage? If you can wire in series it can be wired simpler and lower amps.

Seems odd you are not wiring solar negative directly to the SCC. Any reason for that?

You show a 200A fuse to your 2000W inverter

2000W / 10V cutoff / .85 efficiency = 235A
You should wire and fuse for 250A or you will blow 200A fuses as you approach 2000W inverter loads.
Click to expand...
 
Hey thanks for the feedback as well, in looking at my manual it looks like it shows Solar to battery neg and a terminal from SCC to battery neg so i could just simply connect the solar to the neg on the SCC and then run the line to the negative battery/bus if it’s all the same. SCC max input is 50v so I could go series i just thought parallel would be simpler and honestly i know it makes the amps lower but i don’t understand why i would other than cable size (does it charge quicker or something since more volts)? Thanks for the explanation on inverter I thought it was 2000w/12v/.85 —> 196, i assume 12v doesn’t mean 12 volts then haha . Appreciate you .
 

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MisterSandals said:
8AWG from your panels seems like overkill. What are your panel specs? 10AWG should be plenty with most 200W panels 2P.
What is your SCC max input voltage? If you can wire in series it can be wired simpler and lower amps.

Seems odd you are not wiring solar negative directly to the SCC. Any reason for that?

You show a 200A fuse to your 2000W inverter

2000W / 10V cutoff / .85 efficiency = 235A
You should wire and fuse for 250A or you will blow 200A fuses as you approach 2000W inverter loads.
Click to expand...
Hey thanks for the feedback as well, in looking at my manual it looks like it shows Solar to battery neg and a terminal from SCC to battery neg so i could just simply connect the solar to the neg on the SCC and then run the line to the negative battery/bus if it’s all the same. SCC max input is 50v so I could go series i just thought parallel would be simpler and honestly i know it makes the amps lower but i don’t understand why i would other than cable size (does it charge quicker or something since more volts)? Thanks for the explanation on inverter I thought it was 2000w/12v/.85 —> 196, i assume 12v doesn’t mean 12 volts then haha . Appreciate
 

Attachments

  • IMG_4094.jpeg
    IMG_4094.jpeg
    203.3 KB · Views: 0
MisterSandals said:
8AWG from your panels seems like overkill. What are your panel specs? 10AWG should be plenty with most 200W panels 2P.
What is your SCC max input voltage? If you can wire in series it can be wired simpler and lower amps.

Seems odd you are not wiring solar negative directly to the SCC. Any reason for that?

You show a 200A fuse to your 2000W inverter

2000W / 10V cutoff / .85 efficiency = 235A
You should wire and fuse for 250A or you will blow 200A fuses as you approach 2000W inverter loads.
Click to expand...
Should my fuse for leaving the battery be 250 then even though my battery max discharge is 200amps with a 200amp BMS? Hope that’s not a dumb question
 
Helpmenotblowupmywife said:
Should my fuse for leaving the battery be 250 then even though my battery max discharge is 200amps with a 200amp BMS?
Click to expand...
The fuse protects the wire so should be sized to blow before the wire fails. BMSs aren't foolproof so you cannot count on the battery output being limited to the BMS rating.

Helpmenotblowupmywife said:
I thought it was 2000w/12v/.85 —> 196, i assume 12v doesn’t mean 12 volts then haha .
Click to expand...
Batteries don't only output 12V. Sometimes its 14V, sometimes its 10V. Instead of using 10V blindly, use YOUR inverters cutoff voltage for this calculation.
 
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