High voltage input warning

jneale519

I have an off grid solar system in a school bus conversion. I keep getting a high voltage warning and my solar will stop charging my batteries. I have 4, 315 watt solar panels in series coming into a 100 amp mppt solar charge controller, 6 180ah agm batteries wired in parallel and a 3000 watt pure sine inverter. I run a small refrigerator off the 110 a few outlets and everything else is 12v. 

mike95490

Just guessing and tossing out things to consider

Is the voltage warning on the PV side or the Battery side ? 

Have the days been unusually cool or sunny ?

i see no need to have 4 panels in series, to charge 12V battery.  The voltage of 4 in series could approach the input limit of your controller, triggering a shutdown.  Wired 2S2P would still allow the MPPT to function efficiently, and with less conversion loss from high DC voltage to 12V.  with 2 in parallel, you would have more amps in the PV loop, but is it enough to matter - depends on the gauge of the existing wire and the distance from panels to charge controller.

Photowhit

jneale519 said:

I keep getting a high voltage warning and my solar will stop charging my batteries. I have 4, 315 watt solar panels in series coming into a 100 amp mppt solar charge controller, 

So what are the spec's on your charge controller?


Not a lot of 100 amp charge controllers out there. Could be an off brand, but I'd post a few and their spec's;

Aims; Max PV open circuit voltage: 155Vdc
https://www.amazon.com/Aims-Power-SCC100AMPPT-Charge-Controller/dp/B078VL7HGX

EPever; Max. PV open circuit voltage: 150V
https://www.amazon.com/EPEVER-Charge-Controller-Flooded-Tracer10415AN/dp/B07JVQY8QB

Renogy RVR100;
Magnum;

Maximum PV input voltage (any condition)

200 VDC + battery voltage or 240 VDC - whichever is lower

Here are some 315 watt solar panels with math for basic VOC voltage in a string of 4 panels (the VOC will be higher when very cold)

Canadian solar VOC=Voltage (VOC)40.1V 410.1V x 4 =  160.4V

LONGi VOC= 37.9 volts x4= 151.6 volts

These are modern 120 cell panels

Previous they would normally be 72 cell panels Like;

REC 315PE72 VOC=45.5 x 4 = 182 volts

SW315 Mono - SolarWorld VOC= 45.6 x 4 = 182.4 volts

Trina-Solar TSM-315 voc=45.6...

The voltage of strings of 4 are usually too high for standard MPPT charge controller, The Magnum can handle most of these, but the others aren't realistic.

I'd suggest switching your configuration to 2 pairs of 2 panels. You can do this on the top of your bus with "Y" connectors, Like these;



...and still use the same wires bringing the power into the bus. Check the ampacity of the wire! and your breaker/fuse size.

jneale519

Thanks I have the Epever 100a mppt  and I'm using 2gauge wire from  solar charge controller. 

Photowhit

jneale519 said:

Thanks I have the Epever 100a mppt  and I'm using 2gauge wire from  solar charge controller. 

So 4 - 315 watt solar panels don't have a VOC above the 150 volt limit?

What panels do you have?

SafariParkEarth

Good info here - you can't go above the max input voltage for your controller/inverter.

littleharbor2

SafariParkEarth said:

Good info here - you can't go above the max input voltage for your controller/inverter.

Unless you have Midnite Classic charge controllers with Hyper VOC feature, You can add your nominal battery voltage to the Max VOC rating. A Classic 200 in a 48 volt system can tolerate 248 volts max VOC. That being said, a properly designed PV system should never need to get anywhere near the max VOC.