Need Help/Advice

[HRTKD]

179 volts from five panels that (I think) have Voc = 32.9. I pulled that Voc from this spec page, but it could be a different model. It must be cold to get that many volts.

I'll go out on a limb here and say that the system looks good. The lack of sufficient sun due to snowfall and leaving the inverter on is the likely culprit. If some device was left on, drawing AC power through the inverter then that was the nail in the coffin. Without knowing the specs of your charge controller, I don't see a red flag, at least not in the wiring. The battery connections weren't made haphazardly. Someone put some thought into connecting the batteries in an optimal configuration.

Charging at only 8.6a is a killer. Total optimal panel production of 3100 watts down to just 8.6a out of the solar charge controller. Wow. It's going to take a long time to bring those batteries up to a full charge. Some monitoring needs to performed to see if the batteries ever do get fully charged.

GSXR1000, I saw your comment betting that they were wired in parallel. Man, wiring 10 panels in parallel is a lot of work. I can't imagine an installer doing that much work when a 5s2p configuration is a lot less time, effort and cost.

 

[GSXR1000]

I don't see how you can have 3000 watts and only be making 100w?
bad panel angle, setting wrong on solar charger...

 

[Hedges]

Yes, 100W from 3000W was what I noticed too.
Could be very little sun on the panels.
But, I've had dead car batteries before. Initially on a charger their current draw was low, later it came up.
So I would keep watching it, also examine panels to see if they are shaded (or covered in snow.)
We don't know what the performance of this system was before.
If, for instance, a single series string of panels had panels in multiple orientations, current from the string would always be limited to the poorest performing panel. That would be something to correct by reconfiguring the array.

OP - do you have a photo of the PV panel array(s)?

 

[HRTKD]

There are a couple leads coming off the battery terminals, that are power cables. That may be for the solar charge controller. I was looking to see if there was a temperature sensor for the solar charge controller. If there is (doesn't look like it), then maybe the controller is limiting charge due to very low temperatures.

 

[upnorth]

The panels were installed at the recommended angle but was a fairly cloudy day today and last display picture was taken later in the day when a bit of shadowing occurs as well. Here is a picture of the set up. Sunset is at 5:00 pm.

 

[HRTKD]

The panel angle in those pictures looks good for summer. Bad for winter. I suspect they should be close to 18° from vertical for November.

 

[GSXR1000]

The panels were installed at the recommended angle but was a fairly cloudy day today and last display picture was taken later in the day when a bit of shadowing occurs as well. Here is a picture of the set up. Sunset is at 5:00 pm.

strange.. middle of a sunny day note the watts produced .. then add a load and see if it increases ( maybe the batteries aren't accepting charge)

 

[GSXR1000]

The panel angle in those pictures looks good for summer. Bad for winter. I suspect they should be close to 18° from vertical for November.

still wouldn't explain only 10% output IMO

 

[Hedges]

All facing the same direction, so that rules out a series connection of two differently oriented panels.
If heavy clouds and at a time of day when sun at an angle to panels, could explain the low charge current. See what happens middle of the day tomorrow if skies are clear.

Angle may not be optimum for winter, but it is an angle. You'll get a large fraction of peak winter power during middle of the day.

As GSXR1000 said, testing with a load on the inverter would show if current was available from charge controller, just not being accepted by the batteries. But in that case I think it would go higher than 11.9V

 

[HRTKD]

still wouldn't explain only 10% output IMO

Agreed.

 

[upnorth]

Tomorrow is cloudy with snow but sunny Thursday so will try to check right at noon. So just to try and understand this, let’s say it still says 100 watts in and I have the inverter on and then turn on the toaster or microwave, then the number of watts produced coming in would be higher???

 

[Hedges]

If the battery accepts the current, charge controller will already be delivering all the watts that are available.
Turning on inverter and toaster would simply divert power to the inverter and start draining battery.

More common is when someone's battery is almost fully charged. They add more panels and ask, "Why don't I get any more watts?"

Lead acid batteries are first charged in "bulk" mode, all current available is delivered (or for some systems, the maximum programmed current is delivered.) Your charge controller indicates this mode.

Then, in "absorption" mode, a constant voltage. The battery only takes the current it wants, then tapers off. If you turn on the toaster during absorption, charge controller will deliver more power, more current, but voltage will remain the same. (so long as enough PV is available). Battery charge current will remain the same. Extra current from charge controller will go to inverter.

Finally, "float" mode, a lower constant voltage. Just enough to keep batteries from discharging. My 405 Ah 48V bank registers 0.1 kW at that point, exact value not certain because that is a single count of the display.

 

[SolarQueen]

179 volts from five panels that (I think) have Voc = 32.9. I pulled that Voc from this spec page, but it could be a different model. It must be cold to get that many volts.

I'm changing my answer, I think I needed a nap. Vmp is 32.9, Voc is 40.1. Five in series is fine with a Classic 250. Even at -40, you are just barely hitting 250V, in which case the Classic will protect itself. (40.1V x 5 x 1.25 = 253V). However, the output of the Classic 250 is 63A. If you have 3100W / 24V system, that's 129A output. Do you have 2 charge controllers, with 5 in series going to each one?

 

[upnorth]

Nope just one midnite classic 250 charge controller.

 

[digitalsteve]

Ok I will attach a shot of the midnight display with sun on the panels. Also the diagram that was provided by the guy that sold me the system - I think they are wired as 2 strings of 5. The last diagram is a diagram my Dad did just now of how the batteries are hooked up. It seems to be charging the batteries so I would assume everything is hooked up ok??

What do you guys think??

Should you decide to charge with a 12 volt charger connected to your Yamaha generator, you should attach the + (positive) to any of the red dots and - (minus) to any of the black dots. You can pick the ones most convenient.

 

[upnorth]

Thanks digitalsteve. If the charger is hooked up as you indicate and plugged into generator to charge, does the inverter just need to be turned off or disconnected? And what about the charge controller? Does it have to be disconnected?

If I am not up there for 6 or 7 weeks, do you think there is any advantage to loading up the batteries and taking them home and storing in my heated garage at home? I was told by the guy I got them from that if they freeze it won’t damage them but not sure about it?

 

[HRTKD]

Your battery charger can be hooked up without unhooking anything else. For maximum charge, turn off the inverter.

Leaving batteries in the cold should only be done if they are fully charged. A battery low on charge can freeze, which is bad. If you aren't confident that the batteries are fully charged, I would take them home where you can charge them.

 

[digitalsteve]

Ok I will attach a shot of the midnight display with sun on the panels. Also the diagram that was provided by the guy that sold me the system - I think they are wired as 2 strings of 5. The last diagram is a diagram my Dad did just now of how the batteries are hooked up. It seems to be charging the batteries so I would assume everything is hooked up ok??

What do you guys think??

Couple of interesting items regarding the readings on the charge controller: The battery voltage is 11.9v. Since a gel cell at (11.8v =0% state of charge) and a 25% state of charge is12.0v, (50% will be at 12.3), so I am guessing you might have 10% charge at this point. Which is about what you would have charged in 10 hours at 8.6 amps charge rate. Adding a 50 amp charger to the mix, might get you to a full charge in 24 hours or so, but that is running your generator for the whole time.

As others have mentioned, you should be getting much higher charge rate from the panels. Even at 1/3 their rating, you would have 1000watts which is about 80 amps to the batteries. Make sure you don't have a tripped breaker of blown fuse in the combiner box.

 

[digitalsteve]

Thanks digitalsteve. If the charger is hooked up as you indicate and plugged into generator to charge, does the inverter just need to be turned off or disconnected? And what about the charge controller? Does it have to be disconnected?

If I am not up there for 6 or 7 weeks, do you think there is any advantage to loading up the batteries and taking them home and storing in my heated garage at home? I was told by the guy I got them from that if they freeze it won’t damage them but not sure about it?

You could leave on the inverter, but the batteries would charge slower. From Google " While it is true that many AGM batteries are able to deliver a higher percentage of rated capacity at lower temperature, Gel batteries are quite capable at lower temperature and many are rated to operate at temperatures as low as -76°F (-60°C)" But it is best to check the specs for your batteries. The charge controller may help charge the batteries faster.

 

[Hedges]

I'm changing my answer, I think I needed a nap. Vmp is 32.9, Voc is 40.1. Five in series is fine with a Classic 250. Even at -40, you are just barely hitting 250V, in which case the Classic will protect itself. (40.1V x 5 x 1.25 = 253V). However, the output of the Classic 250 is 63A. If you have 3100W / 24V system, that's 129A output. Do you have 2 charge controllers, with 5 in series going to each one?

But he has a 12V system, so 3100W/12V = 258A.
With the one charge controller he can only get 1/4 of that, about 750W. Hopefully just due to a cloudy afternoon they were getting 100W
The batteries (400 Ah 6V connected 2s2p) would prefer 170A but allow a maximum of 250A

You really do need a nap!

More charge controllers would let him harvest more. Only so many ways to divide 10 panels evenly; maybe a different model charge controller could split it up better.

I'd like to re-orient panels to reduce the peak and increase the hours of good production, but the nice solid ground mount is already there.
With optimum multiple orientations, it would make the ideal 170A for several hours per day.