Gauge of solar panel wires on Magnitude

[LarryD]

Anyone happen to know what gauge wire is used on the 100 watt panel that comes with the Magnitude? I'd like to throw a few more panels up there but not start a fire. thanks!

[16ACE27]

Probably 10 gauge, as are all other Thor solar installs. You can always wire panels in series (if the controller can handle the voltage) to keep amps within cable limits.

[macdaddy1111]

Originally Posted by LarryD

Anyone happen to know what gauge wire is used on the 100 watt panel that comes with the Magnitude? I'd like to throw a few more panels up there but not start a fire. thanks!

Post from another op that I snagged

[DavidEM]

That is a nice chart. It is the only one I have seen that gives the maximum fuse size for various wire gauges, the type of fuse and inside and outside of the engine room usage.

But realize that this is the maximum current a wire can carry. Depending on run length, there may be a substantial voltage drop. For example two 100 watt panels mounted on the roof in parallel with a 20’ run to the controller could result in about a half volt drop. Double that with four panels wired in parallel.

As noted above, much better to wire them in series or series/parallel to cut the voltage drop and power losses in half. But only if you use a MPPT controller.

David

[Rvland]

100w divided by voltage 12vdc = 8.3 amps. #12 is good for 20 about 17amps under continuous use.

[DavidEM]

Originally Posted by Rvland

100w divided by voltage 12vdc = 8.3 amps. #12 is good for 20 about 17amps under continuous use.

True, 12 gauge can handle the current output of two 100 watt panels wired in parallel. But the voltage drop on a twenty foot run would be about 1.1 volts, so you will lose almost 10% of your panel’s output.

Better to increase the wire gauge, and/or wire the panels in series to reduce voltage drop losses.

David

[williamprunty]

I believe the magnitude is prewired for 3 solar panels. I know I added panels and they didn’t need to do any additional wiring. It was plug and play

[Chateau_Nomad]

Things to consider...

https://www.anker.com/blogs/solar/so...es-vs-parallel

[LarryD]

I think I can fit 2x400 watt and 1 more 100 watt up there for a total of 1000watts @48v nominal with 90v at max. so so max 20 amps @48v and 11 amps @90v. Will also upgrade the MPP to handle the voltage.

[DavidEM]

Originally Posted by LarryD

I think I can fit 2x400 watt and 1 more 100 watt up there for a total of 1000watts @48v nominal with 90v at max. so so max 20 amps @48v and 11 amps @90v. Will also upgrade the MPP to handle the voltage.

How are you going to wire these panels? FWIW, 90 volts requires a different wiring system, similar to 120 V AC.

No matter how you wire them, S, P, SP, you will see a large voltage drop in the OEM 10 gauge roof to controller wiring.

David

[Chateau_Nomad]

Use 10AWG pure copper stranded cable with UV resistant jacket designed for solar panel installs. You could use 8AWG, but it's probably overkill. Then... route the final two conductors down through the roof refer vent. As stated, I would not trust the OEM cabling.

[LarryD]

Originally Posted by DavidEM

How are you going to wire these panels? FWIW, 90 volts requires a different wiring system, similar to 120 V AC.

No matter how you wire them, S, P, SP, you will see a large voltage drop in the OEM 10 gauge roof to controller wiring.

David

not sure I understand your question, what do you mean a "different wiring system"? I'd like to wire all four panels in series using the stock wiring so as not to have to run new wires (I do not want to penetrate the roof). Other than a different MPP everything remains the same.

[LarryD]

Originally Posted by Chateau_Nomad

Use 10AWG pure copper stranded cable with UV resistant jacket designed for solar panel installs. You could use 8AWG, but it's probably overkill. Then... route the final two conductors down through the roof refer vent. As stated, I would not trust the OEM cabling.

need to look to see the viability of this path but I'd like to avoid running wires down thru the coach. I appreciate why you dont trust OEM wiring but not sure I share that concern.

[Chateau_Nomad]

Originally Posted by LarryD

need to look to see the viability of this path but I'd like to avoid running wires down thru the coach. I appreciate why you dont trust OEM wiring but not sure I share that concern.

My reason was primarily because I relocated the batteries under the bed in the rear of the coach... which were formerly under the entry steps... classic class C location. And... nobody sees those cables - they're completely hidden inside the chase... AND appropriately and securely attached - AND not with staples!

Secondly, I mounted all the related goodies (solar controller, PV switch, battery disconnect, inverter/charger and power-in fuse block) in the adjacent storage on the driver side rear of the coach.

Since I did the entire installation myself I know exactly where everything is located and the quality of components. Although not everyone's cup-o-tea, there's something to be said about doing your own design, layout, schematics and construction/install.

[LarryD]

Originally Posted by Chateau_Nomad

My reason was primarily because I relocated the batteries under the bed in the rear of the coach... which were formerly under the entry steps... classic class C location. And... nobody sees those cables - they're completely hidden inside the chase... AND appropriately and securely attached - AND not with staples!

Secondly, I mounted all the related goodies (solar controller, PV switch, battery disconnect, inverter/charger and power-in fuse block) in the adjacent storage on the driver side rear of the coach.

Since I did the entire installation myself I know exactly where everything is located and the quality of components. Although not everyone's cup-o-tea, there's something to be said about doing your own design, layout, schematics and construction/install.

makes sense. Did you have anyone review your design before hand? Im now thinking I should up he voltage by going with 4x200 watt panels rather than 2x400 watt panels. The Victron MPP TR-VE can handle 250v input.

[Chateau_Nomad]

Originally Posted by LarryD

makes sense. Did you have anyone review your design before hand? Im now thinking I should up he voltage by going with 4x200 watt panels rather than 2x400 watt panels. The Victron MPP TR-VE can handle 250v input.

Why would I need someone to review?? All the calculations can be found online. After doing an energy audit for average watt hours, I had a handle on what components I needed. Then I decided where I wanted those components to fit in the motorhome and did ampacity calculations for the length of cable runs, etc. Then came a layout diagram and schematic... followed by ordering around $4k worth of tools and parts to complete the project.

And yes if I were you I'd use 200 watt panels in series to keep amperage down, which allows thinner gauge cable over longer runs. All of this discussed previously.

[PSDtime]

Originally Posted by williamprunty

I believe the magnitude is prewired for 3 solar panels. I know I added panels and they didn’t need to do any additional wiring. It was plug and play

This is true, looking at the schematic, it states
"Boondocking-480W Solar Panel,
1) Install 30 AMP Solar Controller
2) Replace 20A Fuse with 30A Fuse."

So the wiring is the same, you just need to upgrade the solar controller and upgrade the fuse. Make sure to inspect the fuse holder. Mine came with the 480W solar and I noticed that the wires to the fuse holder were getting hot, they must have damaged them. I replaced it and all is well.

[tuchmybuttercups]

Originally Posted by LarryD

Anyone happen to know what gauge wire is used on the 100 watt panel that comes with the Magnitude? I'd like to throw a few more panels up there but not start a fire. thanks!

In case you will be running additional wiring, here's a wire selection chart to determine gauge based on round-trip length and current.