Mixing different gauge solar panel cables..

[ReaderOfEyes]

I have a problem. Being completely new to solar power, I have already made my first big mistake. And I haven't even received all of my components yet !
Any way, I ordered a solar panel, extension cables and a charge controller ( all from different sellers ). After I received my panel, I came to find out the panel has 12AWG output cables with MC4 connectors attached to them. The extension cables, which should arrive any day, are 10AWG cables with MC4 connectors on one end only. Can these extension cables be used with this panel, or did I just totally waste $50 on cables I can't even use? The cables are non-returnable.
I know I could buy another solar panel that has 10AWG output cables on it, but being completely new to solar energy I would rather not attempt a multi-panel system until I get a lot more experience with solar energy systems. Also, I don't have the money for another panel AND another set of extension cables ( to work with the panel I already bought ). I believe I can swing the cost of another set of cables, if I absolutely have to.
Thanks for any help in this matter.

[peakbagger]

Dont worry about it. Unless you have multiple panels in series you are nowhere near the amperage capacity of the cables. There are online calculators for amperage.

The typical installer buys one extension cable with connectors on both ends and then cuts it in half. You most likely paid for the privilege of someone cutting it in half for you. Unless you specified a connector setup, they will send you one male and one female extension cable.

Make sure you get the polarities right and I hope you arent planning to tie into the grid with the setup you bought unless you go legit and get a permit. Power companies get quite grumpy about that and usually the low cost "grid tie " inverters arent certified for grid tie applications in the US.

[ReaderOfEyes]

Mixing different gauge solar panel wires......

My only concern in this matter is whether or not the two different gauge cables can be connected together and run to my controller without messing up the solar panel or the controller. I don't know if you can run a 10 gauge wire off of a 12 gauge wire without messing anything up or causing a voltage loss or anything like that.
I don't know if it matters, but the panel is a 100W with short circuit amperage of like 5.89A.
Also, I don't intend to use this as a grid-tie system. I want it for powering some lights and small tools in a building that has no electric service.
Thanks for any further advice.
Have a great day.

[Ian S]

My only concern in this matter is whether or not the two different gauge cables can be connected together and run to my controller without messing up the solar panel or the controller. I don't know if you can run a 10 gauge wire off of a 12 gauge wire without messing anything up or causing a voltage loss or anything like that.
I don't know if it matters, but the panel is a 100W with short circuit amperage of like 5.89A.
Also, I don't intend to use this as a grid-tie system. I want it for powering some lights and small tools in a building that has no electric service.
Thanks for any further advice.
Have a great day.

For the system setup you describe, I can see no problem with using the 10 gauge extension wires with the 12 gauge coming off the panel. The gauge or wire thickness is important in determining the amperage the wire can handle. 12 gauge wire can easily handle 6 A.

[Naptown]

The # 10 cables you bought are absolutely fine. Bigger than may be necessary but will only improve performance (OK maybe very slightly)
As long as the connectors click together which they will as both are MC4 you are good to go.

[ReaderOfEyes]

Mixing different gauge solar panel cables....

Thanks for the help, everyone. Now I can stop worrying about the cables and go back to being anxious to try out the system, after I get the rest of my components.
I appreciate the information a lot.

[Aussiemike]

I know this is old but it also interests me and I would love to hear it further explained.
Just to exaggerate what if you had a run of 30 feet of 6AWG and a run of 5 feet of 12AWG.
Is there a formula to let me know the max amp for this line?
Do I just assume the whole 35 feet is 12 AWG?
Cheers Mike

[Mike90250]

The max amp, is 20A, because that's what 12ga is rated for. For ohmic electrical loss, you add the resistance from the 6ga & 12ga lengths

[Aussiemike]

Thanks Mike.
So effectively the 6AWG is completely wasted.

[NewBostonConst]

The six awg will be more efficient over a long distance so you are gaining there and that is common...yes, Mike is correct you have to size everything on your smallest conductor. Fuses and Circuit breakers are sized to the wire and to protect the wire.

[Mike90250]

Thanks Mike.
So effectively the 6AWG is completely wasted.

No, it is a meaningful length of low resistance (low loss) cable.

[Aussiemike]

Thanks Mike

[Aussiemike]

Morning guys.
Is it ok to attach the battery cables from the Charge Controller to the terminals of the Inverter?
Cheers Mike

[Aussiemike]

Can I use this as a switch and not a circuit breaker? Or does it have to be DC?
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[SunEagle]

Morning guys.
Is it ok to attach the battery cables from the Charge Controller to the terminals of the Inverter?
Cheers Mike

Most charge controllers do not have an output rating big enough for an inverter so they can fail. It would be better to wire the inverter to the battery terminals.

Some type of DC voltage rated disconnect device needs to be used between the battery and inverter. If that circuit breaker is not DC voltage rated then you really shouldn't use it.