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24V System Wire Sizing help

JonBartee7

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Hello everyone, this is my first post on the forum.
I am currently in the planning and buying phase of my solar upgrade on my RV.
I have a 2022 Grand Design Transcend Xplor 231RK travel trailer (non-motorized)

I need some help figuring out wire sizing and fuse/breakers needed at a couple points in my build and haven't been able to find too much information relating to 24V systems.

I am following the explorist.life diagrams and videos as well as various other resources (Will Prowse of course)

Things I need to figure out:

From Inverter to Breaker box: what size triplex wire? what size breaker in ac distribution panel?
- RV is about 25 feet from inverter to breaker and from shore power to inverter so I would like to get 30 ft wire for clearance


What size ANL fuses at each connection in lynx distributor? (inverter, dc block, scc) (Answered: Inverter-250A, scc-150A, dc distribution-inline fuses)
From shore power to inverter: What size triplex wire? (Answered: 10awg Triplex)
What gauge wire from lynx to 12v dc block? (Answered: 10awg)
Is 2awg from SCC to lynx correct for my system? (Answered: 4awg)
Is 4/0 necessary from lynx to inverter, chassis ground, and batteries? (Answered: 1/0)

Sorry for all the questions but this is all I have left to figure out and would love to get it all sorted out so I can buy all the wiring/fuses necessary.

I have edited the explorist.life diagram to suit my setup for reference.
Everything else that has not been whited out I am using in my system except I am replacing the bmv-712 with a smartshunt.
24->12V converter will be added for dc block.
Any tips or constructive criticism outside of the scope of my questions is welcomed.
Wiring Diagram Edited.png
 
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Ah yes sorry I forgot to add that but I have one in my amazon cart.
Edited original post.
 
Suggest you use a single battery
 
Already bought the 2 12v 200ah batteries because they were cheaper by like $300 and each will weigh less individually for maintenance/replacing/installing.
 
I have a attached a textual representation of your topology including wire guage and fuse size.
If you have any questions just holler.
 

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Thank you! this is very helpful!
Just a couple questions to clarify everything.

I have a preinstalled solar setup on the RV and 10awg wires are already routed to the battery from dc block. Could I just use 10awg for everything from busbar<->converter<->dc block since I already have it prewired and have excess 10awg wire?

Are all the fuses listed, besides the shunt fuse, ANL or MEGA fuses?

Are the 30A fuses listed from converter to dc block actually fuses or breakers in the dc block?

Most importantly, I don't see any recommendations for triplex wire size from shore power to inverter or ac distribution to inverter. explorist.life suggested 10awg triplex from shore power to inverter and 6awg from inverter to ac distribution with a 3000W 12V inverter but I assume I can go smaller since I am using 24V. triplex is pretty expensive for 30ft so trying to reduce cost.
Also need to know what size breaker for the inverter to ac distribution. explorist.life suggested 50A

And is this dpst correct for scc to solar panels?
 
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Thank you! this is very helpful!
Just a couple questions to clarify everything.

I have a preinstalled solar setup on the RV and 10awg wires are already routed to the battery from dc block.
What dc block?
10 awg is only good for 24 service amps.
24 amps / .8 fuse headroom is 30 fault amps.
Is this pv wire?
Could I just use 10awg for everything from busbar<->converter<->dc block since I already have it prewired and have excess 10awg wire?
see above.
Are all the fuses listed, besides the shunt fuse, ANL MEGA fuses?
shunt.positive will be an inline automotive style fuse in an in-line holder.
For the dc2dc converter you can use 10 awg and a 20 amp in-line fuse for the in leg and 10 awg with a 30 amp fuse on the out leg.
Both in in-line carriers.
I really don't like those cheap amazon dc2dc converters.
What is the amp rating for the legacy ac2dc converter?
I suggest you use that as a minimum size.
Are the 30A fuses listed from converter to dc block actually fuses or breakers in the dc block?
fuses.
You system only needs 2 points of administrative disconnect.
That is the double pole single throw switch between the panels and the solar charge controller and the disconnect switch between the battery and the positive busbar.
Most importantly, I don't see any recommendations for triplex wire size from shore power to inverter or ac distribution to inverter
If its a 30 amp shore power connection then 10 awg is fine.
. explorist.life suggested 10awg triplex from shore power to inverter and 6awg from inverter to ac distribution with a 3000W 12V inverter but I assume I can go smaller since I am using 24V. triplex is pretty expensive for 30ft so trying to reduce cost.
24 volts is the dc voltage rating and is orthogonal to the ac side wire spec.
You need 10 awg in and out of the inverter because when the inverter is in bypass mode it can pass the full shore power downstream.
The specs look acceptable but I have no experience with the brand.
 
What dc block?
10 awg is only good for 24 service amps.
24 amps / .8 fuse headroom is 30 fault amps.
Is this pv wire?
not pv wire. When I say dc block I mean dc distribution panel. you recommended 12awg from lynx to converter, 10awg from converter to dc distribution, 10 awg from dc distribution to negative on converter, and 20 awg from converter to negative busbar. also not sure why the wires going into converter would be ok to be smaller than going out. is that because it is 24V coming in and 12V going out?

For the dc2dc converter you can use 10 awg and a 20 amp in-line fuse for the in leg and 10 awg with a 30 amp fuse on the out leg.
between converter and lynx distributor correct? so could I put those in the fuse slots in the lynx if I have enough room? to save money on extra fuse holders

I really don't like those cheap amazon dc2dc converters.
Any reason why? affordable alternatives? victron orion is a little much for a converter

Regarding the triplex wire, just wanted to confirm 10awg can be used for inverter to ac distribution, explorist.life had this to say about it and want to make sure I wont overload the wire in this circumstance:

"6/3 stranded wire is used here because although our shore power is 30A max, which 10 gauge wire is adequate for, the PowerAssist function of the Victron Multiplus Inverter Charger can add up to 3000w of battery power to shore power in the event that more power than the shore power can provide is needed. This much power coming from the Inverter/Charger requires 6 gauge wire feeding a 50A main breaker in the AC distribution panel."

Please post the panel specs.
Which panel are you referring to?
 
not pv wire. When I say dc block I mean dc distribution panel. you recommended 12awg from lynx to converter, 10awg from converter to dc distribution, 10 awg from dc distribution to negative on converter, and 20 awg from converter to negative busbar. also not sure why the wires going into converter would be ok to be smaller than going out. is that because it is 24V coming in and 12V going out?
That is a typo.
Should be 12 awg with 20 amp fuse on the in leg and 10 awg with 30 amp fuse on the out leg.
40 amps at 12 volts nominal is 20 amps at 24 volts nominal.
between converter and lynx distributor correct?
The diagram should make this clear.
lynx to dc2dc converter is 12 awg.
Actually you can use 10awg with a 30 amp fuse on the in leg.
dc2dc converter to dc distribution panel is 10 awg with its own 30 amp fuse.
That will make things simpler.
so could I put those in the fuse slots in the lynx if I have enough room? to save money on extra fuse holders
The lynx distributor will only use mega fuses.
The smallest mega fuse is 60 amps.
I suggest you use ring terminals and in-line fuses and stack the low current connection on top of the high current connections.
You could also tap the right hand side of the backplane.
Any reason why? affordable alternatives? victron orion is a little much for a converter
In my experience they are cheap crap with zero quality control.
Some of them probably work fine.
Some of them melt wires.
What is the amp rating on the legacy converter?
That is the minimum size you should be looking at.

Regarding the triplex wire, just wanted to confirm 10awg can be used for inverter to ac distribution, explorist.life had this to say about it and want to make sure I wont overload the wire in this circumstance:

"6/3 stranded wire is used here because although our shore power is 30A max, which 10 gauge wire is adequate for, the PowerAssist function of the Victron Multiplus Inverter Charger can add up to 3000w of battery power to shore power in the event that more power than the shore power can provide is needed. This much power coming from the Inverter/Charger requires 6 gauge wire feeding a 50A main breaker in the AC distribution panel."
I forgot about power assist.
Is your inlet 30amps or 50?
What is the rating on the master breaker in the ac distribution panel?
Which panel are you referring to?
The PV panels.
open circuit voltage and short circuit current.
 
Revised to correct typo.
 

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stack the low current connection on top of the high current connections.
You could also tap the right hand side of the backplane.
Not sure what you mean by this

What is the amp rating on the legacy converter?
I attached some pictures of the breaker box and specs for AC & DC distro and preinstalled converter.

Is your inlet 30amps or 50?
What is the rating on the master breaker in the ac distribution panel?
30 AMP inlet. 30A breaker for main in AC distro panel
The PV panels.
open circuit voltage and short circuit current.

  • Rated Power: 250W
  • Open circuit voltage (VOC): 37.6 V
  • Max power voltage (VMP): 30.3 V
  • Short circuit current (ISC): 8.85 A
  • Max power current: 8.27 A
  • Power Tolerance 0/+3%
  • Maximum system voltage: 600V (UL)
  • Fuse Rating: 15
 

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Not sure what you mean by this
the lynx distributor has 4 fused positions.
You have 3 high current circuits and 2 low current circuits.
The minimum fuse size for the lynx is 60 amps.
High current wires are usually terminated with compression lugs.
Low current wires are usually terminated with ring terminals.
A ring terminal is approximately the same thickness as a flat washer.
I propose we connect the dc2dc converter circuit like this.
the protruding end of the positive and negative back plane have 8mm(5/16") diameter holes.
You will use these
to attach a disconnect switch to the positive backplane
and you will attach a shunt to the negative backplane
You would also attach this via a ring terminal
https://www.waytekwire.com/item/46238/ATO-ATC-In-Line-Fuse-Holder-46238-/
to something downstream of the disconnect
The ring terminals will replace a flat washer in the stack
from bottom up
terminal, compression lug, ring terminal or flat washer, lock washer and finally fastener.

You will attach the stunt positive lead which will probably have its inline fuse to the upstream side of the disconnect switch.
That way the shunt won't lose power when you isolate the battery from the rest of the system.

I attached some pictures of the breaker box and specs for AC & DC distro and preinstalled converter.


30 AMP inlet. 30A breaker for main in AC distro panel
You can up-size the the wire from the inverter to the ac distro panel if you want.
The maximum master breaker size for the panel is 30 amps and the wire has to fit into the screw terminal on the breaker.
I don't really see much point.

The ac2dc converter is 55 amps.
You should be looking for a dc2dc converter at least that ampacity.
  • Rated Power: 250W
  • Open circuit voltage (VOC): 37.6 V
  • Max power voltage (VMP): 30.3 V
  • Short circuit current (ISC): 8.85 A
  • Max power current: 8.27 A
  • Power Tolerance 0/+3%
  • Maximum system voltage: 600V (UL)
  • Fuse Rating: 15
The panels voc is too high to do 1 string of 4 panels in series.
So the next best configuration is 2 strings of 2 panels in series.
 
The panel is nice and tidy inside.
Even used a lever nut for the converter connection.
That is good to see.
 
You would also attach this via a ring terminal
https://www.waytekwire.com/item/46238/ATO-ATC-In-Line-Fuse-Holder-46238-/
to something downstream of the disconnect
ok so I could connect that at the point where the wire coming from the battery connects to the disconnect? then connect the inline fuse wire to the wire going to the positive in on the converter?

You will attach the stunt positive lead which will probably have its inline fuse to the upstream side of the disconnect switch.
That way the shunt won't lose power when you isolate the battery from the rest of the system.
So you're saying to connect the positive lead coming from the SmartShunt I am using to the disconnect where the wire is coming from the batteries?

You can up-size the the wire from the inverter to the ac distro panel if you want.
The maximum master breaker size for the panel is 30 amps and the wire has to fit into the screw terminal on the breaker.
Do you know if there is a way to limit the maximum power being added using powerassist? Cause if I use the 30A breaker and 10awg wire, I don't want it to just trip the main breaker everytime it outputs more than 30A, I'd rather just limit how much power the multiplus contributes to shore.
The ac2dc converter is 55 amps.
You should be looking for a dc2dc converter at least that ampacity.
ok will do. I am not replacing the ac2dc converter though right? Do I need to do any rewiring with the ac2dc converter?

The panels voc is too high to do 1 string of 4 panels in series.
So the next best configuration is 2 strings of 2 panels in serie
Yes, I am doing 2 series 2 parallel
 
ok so I could connect that at the point where the wire coming from the battery connects to the disconnect?
Yes shunt positive should be fed upstream of the disconnect.
then connect the inline fuse wire to the wire going to the positive in on the converter?
The converter shuold be fed downstream from the disconnect.
So you're saying to connect the positive lead coming from the SmartShunt I am using to the disconnect where the wire is coming from the batteries?
Can't parse you.
See my first in-line reply ^
Do you know if there is a way to limit the maximum power being added using powerassist?
Its all configurable.
I would have to look it up.
I think Andy covers the topic in this video.
Cause if I use the 30A breaker and 10awg wire, I don't want it to just trip the main breaker everytime it outputs more than 30A, I'd rather just limit how much power the multiplus contributes to shore.
Agree.
ok will do. I am not replacing the ac2dc converter though right? Do I need to do any rewiring with the ac2dc converter?
The dc2dc converter functionally replaces the ac2dc converter.
You should disable the ac2dc converter by turning off the breaker.
You can optionally remove it.
If you remove it you should remove the breaker and put in panel blank.
 
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