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wyattamdahl

wyattamdahl

New Member
Joined
Aug 31, 2020
Messages
50
Location
California
firstly, I am looking to connect 4 100w panels to two 30w panels. is this possible?

Will y branch connectors work to wire them in parallel?
 
They can be connected but there are conditions and limitations. If you provide some detail as to your objectives and other equipment such as charge controller along with the specs for both types of panels (link to product web site or readable picture of spec sheet on back of panel) and battery voltage etc that'd help.
 
If you want to put all six panels in parallel, that should be fine.

MPPT or PWM controller?
 
Your 100s in 2S2P in parallel with your 30s in 2S1P would work too.

Their voltages are close enough that they can be in parallel, but their currents are so far off, they can't be in series with each other.
 
1598918910119.png


is this correct, or will i need to connect 2 two sets of the 100s in series and then 30s in series and run them together in parallel?
 
wyattamdahl said:
is this correct, or will i need to connect 2 two sets of the 100s in series and then 30s in series and run them together in parallel?
Click to expand...
When I see the way you have it wired with all six panels in parallel In the pic above, I’d recommend calculating the amperage through the wiring distance on a DC calculator and see what you got.

On my 600 watts of panels for my 35’ RV, I could not put them all in parallel without getting wires thicker than 10 gauge. Eyeballing what Wyatt said, where he doubles your voltage compared to my calculations on a similar setup I looked at for 2S 3P, that put me needing thicker that 10 gauge wire for the panels or my combiner to charge controller line would have been thicker than the 6 gauge limit on my charge controller, being too physically wire to physically big for the terminal.
 
Scratch everything I said. I didn't realize MPPTs could have that restrictive an input voltage - 25V input limit. Probably has something to do with the alternator charging function.

All panels must be in parallel.
 
I put this through an online DC wire size calculator and for 30 amps at 18 volts and 10 gauge wire and for a 2% drop, I got a max length of 12 feet, or a 6 foot each way. 6 Gauge would get you a 30’ run, or 15 feet each way. 3% may be acceptable, so your wires could be skinnier.

Maybe on a van setup, that would be good.

I originally wanted all six panels in parallel, but the I ould need very thick wires to connect them.
 
snoobler said:
5% drop is acceptable per NEC.
Click to expand...

So with 5% being acceptable, is that just that one leg or all of them. The other two places I measure loss is from the bus bar to batteries, the charge controller to busbar and the busbar to inverter.

I honestly don’t know, but I am adding those four up in my system I’m desigbinf to see the total loss.
 
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