Solar Noob Van Life living Help Please🥺

zeezee5

Hello everyone! I'm doing van life and I've been having the hardest time maximize my solar set up. 
I have a 40a mppt Charge controller. 3 x 200ah batteries and 5 x 100 watt solar panels. It wouldve been 6 but the charge controller said that it was over voltage. Im not understanding why they all aren't being utilized to charge the batteries. Or the charge power isn't higher that at least. Below is the current status of everything.

zeezee5

It's a summer time in LA right now and I really need to be able to use my air conditioner. Pleasee help!

mike95490

with 500w of panels flat on your roof, even harvesting 400w would be a stellar achievement. but 400w is not going to run an AC and recharge you batteries.

I would rewire to 2 panels in series and then parallel the 3 strings into the charge controller

12V batteries @ 600a  is going need 60A for recharge,  600W  of panels in a 12V battery (14.5v recharge) is going to "theoretically" give you 41a, that's below the minimum needed to keep the batteries healthy.

zeezee5

So I need a 60a charge controller?

"I would rewire to 2 panels in series and then parallel the 3 strings into the charge controller" 

 there is only one pv input for solar how would i connect them and also I have them all in series.wjy do you suggest doing so?

wellbuilt

2 panels in series gives lower voltage , then run 3 strings to a combiner box and one lead to the charge controller 

mike95490

All panels in series gives high voltage to the controller, which has to work harder to downconvert to battery voltage.  2x battery voltage (24V) is a good, efficient starting point.

BB.

You did not list the brand/model of MPPT solar charge controller... But probably 2x series x 3x parallel, or 2x series x 3x parallel will work fine...

Need to look at the charge controller input specifications to make sure that your array does not exceed the specs (over voltage is the typical issue).

A 600 Watt array on a 12 volt battery bank w/ MPPT charge controller will output (typical best case):

• 600 Watts * 0.77 panel+controller deratings * 1/14.5 volts charging = 31.9 Amps (near solar noon, on cool//clear day, panels pointed at sun

So you have connectors on the solar panels, or will you just cut the ends off and solder/tape or Wire Nut in weather proof box?

An issue to watch for is how much current is going to the solar charge controller--And the output current too... Need some relatively heavy cables (and kept short from controller to battery bank) to minimize voltage drop...

If you have 100 Watt "12 volt" panels:

• 100 Watts / 17.5 volts "typical" Vmp (voltage maximum power) = 5.71 Amps Imp (current max power)
• 3 strings in parallel * 5.71 Amps Imp * 1.25 NEC derating for solar current = 21.4 Amp suggested branch circuit wiring for 2s * 3p array
• 2 strings in parallel * 5.71 Amps Imp * 1.25 NEC derating for solar current = 14.3 Amp suggested branch circuit wiring for 3s * 2p array

For the charge controller to battery bank:

• 31.9 Amps * 1.25 NEC derating = 40 Amps branch circuit Charger to Battery bank wiring and fuse/breaker rating

You can use this simplified AWG wiring chart for NEC wire Ampacity ratings:
https://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm

21.4 amps => 12 AWG minimum wire
14.5 amps => 14 AWG minimum wire
40 Amp => 10 AWG (high temp wire) or 8 AWG wiring

Technically, you need a fuse or breaker a parallel string if you have 3 or more parallel strings... Another reason that 2x parallel strings is nice (no fuses/breakers needed).

If your panels have connectors, you can use a Y cable like these to connect 3sx2p array:

https://www.solar-electric.com/mumc4colam.html (need male and female pair for + and - wiring)

Make sure you have the solar panel polarity correct (use volt meter)... It is easy to mix the wiring up with connectors/wire nuts.

And to efficient/quickly charge the battery bank--You don't want a large voltage drop from charger to battery bank... Typically suggest 0.05 to 0.10 volt max drop from controller to battery bank @ 31.9 amps.

Lastly, always connect battery bank first, then solar array (under sun). And disconnect array first (under sun) and then battery bank. Connecting a charge controller to the array first can confuse or even possibly damage the charge controller (if doing work in sunlight with panels energized).

-Bill

zeezee5

I have a renogy 40a charge controller and also renogy 200ah batteries.  

BB.

Is this the charge controller?

https://www.renogy.com/rover-li-40-amp-mppt-solar-charge-controller/

Are these your batteries?

https://www.renogy.com/deep-cycle-agm-battery-12-volt-200ah/

If your battery is AGM/GEL/some version of Lead Acid--You need to get it recharged. Lead Acid batteries stored at less than 75% state of charge is not good for them. They will sulfate in days/weeks and eventually be ruined/early death.

-Bill