Wiring solar panels question

[jdhahn1]

I have a small 400W array (4x100W panels) to a 1000W MPP all in one solar charge controller inverter and 206 AH LiFePo4 battery. The run from the panels to MPP station is only about 15-20', battery storage is 12V. Would this system be most productive doing all parallel panel connections to increase amperage since individual panel voltage since the run is short enough that gauge isn't an issue (willing to use large gauge wires if this makes the system better). MPP unit can handle 40amps, 100V. Each 100W panel is 18.6V (22.3V open circuit) and 5.38A (5.86 short circuit). I was originally planning on doing series-parallel layout but I'm now wondering if it makes sense to try and bump up the amps as much as possible for this small off grid cabin system to optimize charging time.

Thanks for your insight!
Justin

 

[Bossrox]

It's best to wire them in series with as many panels as you can while staying below the max volt input of your charger. You don't get any more or less amps either way 'cux your charger coverts the higher voltage, lower amps series wired panels into higher amps on the voltage down conversion to the batts or inverter thus you can get away with smaller wire doing series & save some $$$. Wire size isn't important for voltage but size is critical for amps.

 

[OffGridInTheCity]

There is a case to be made for 2s2p if you have shading issues. For my trailer, I put 2 in series down one side of the roof and 2 in series on the other side and then paralled them. This is because one side get's shadow a lot of the day - which effectively kills any power from that series. If all 4 were in series - shadow on even 1 cell of 1 panel will kill the entire series and you get zip power.

 

[PsXtreme]

I've been running parallel for the past 4 years and only recently in the past few weeks came across Will's videos. I was convinced to try hooking my panels in series and when I did I noticed I have a shorter charge window due to shading, but in that short time I noticed a big increase in the amount of watts going to my batteries. For me it came to parallel having a longer charge window but weak charging power or series with a shorter window but huge increase in power. I choose series for 2 reasons, the huge increase produced more charging power in the long run and also I can get away with using my small 10 gauge wire. From my panels to my charge controller is about 10 feet of wire and voltage travels further in the line than amps do. Keep that in mind as well.

 

[Alphacarina]

The run from the panels to MPP station is only about 15-20', battery storage is 12V. Would this system be most productive doing all parallel panel connections to increase amperage since individual panel voltage since the run is short enough that gauge isn't an issue (willing to use large gauge wires if this makes the system better).

400 watts at 12 volts is more than 30 amps and 20 feet isn't a 'short run' so wire gauge is very important, so yes, if you want them all in parallel, you will need to upsize your wire. 2S2P would be a more reasonable solution

Don