Low Solar Output?

[RebelWithoutACausey]

Im scratching my head on this one.

I just finished the installation of my electrical equipment, and flipped the breaker on the solar array. My setup is 6 x 400 watt panels, wired in sets of 2 in series, and paralleled at the combiner box. From the combiner box, they go straight to the Victron MPPT 150/50.

At noon today, clear skies, no shade, and around 40 degrees (F), the Victron app reported I was getting 1100 watts.

I figured I wouldn't get the full 2400 watts the array is rated for, but this seems low. The max output of the array wired as it is should be 90v and just shy of 30 amps. My peak today was 71v and 15 amps.

What gives?

[rossvtaylor]

Where are you? And what's the layout configuration of your panels on the roof...all in the same plane or do you have them sloped down each side (peaked in the middle)?

[desrtdog]

What system voltage are you running? 12V? 24V?

Also - what panels? (Assuming that they are residential panels by the size/capacity?)

Also - I am not seeing that Victron has a 150/50 solar charge controller...100/50 yes, 150/45 yes, 150/60 yes...but not 150/50...

[RebelWithoutACausey]

Im in North Carolina. All panels are on the same plane, flat across the roof. They are residential style 400w panels. 2s3p wiring configuration.

Battery bank is 24v, 400 ah with two signature solar EG4 batteries, and the controller is the 150/100, my bad.

[RebelWithoutACausey]

I know the panels are dirty in this pic, but we’ve had a lot of rain to clean them off so this is just a demonstration of how the panels are laid out

[desrtdog]

Ok, so the controller should be good up to 2900w on a 24v system. Wondering if there is a bad panel - that would effectively take out thot series pair and reduce your capacity. What are the individual panel specs? (Current seems a little low for 3 arrays in parallel?)

(I am running 2 parallel 400w panels on a 100/50 MPPT and have seen power in the mid/upper 600s … my controller can handle up to 700w on a 12v system.)

[RebelWithoutACausey]

Went up top to the combiner box. I don't have a method of checking amperage but here are the voltage readings of each string, then the voltage once they are all reconnected to the combiner box. I also watched in the victron app, each string I pulled the fuse on resulted in a reduction of power. These readings are at 11:20 AM, clear sky, no shade other than me on the roof.

EDIT: Ignore the attached picture showing no voltage. My probe fell as I was taking the picture and I cant figure out how to delete it.

EDIT 2: I know the panel label is unclear, but each panel max amperage is 9.6A and VOC of 49v, so if 3 strings in parallel, that should put me around 28-29A?

[Booyah45828]

I'd say them being flat is the cause for your low output. According to solarific, the best winter angle for Raleigh, NC right now would be somewhere around 55.9°. Not sure I'd get too deep into troubleshooting low output without changing the angle first, unless you have a prior baseline output that you've achieved from the same setup in years past.

[RebelWithoutACausey]

I think I may have a misunderstanding of the information in the victron app.

I just went back out at 1PM to check, and the app showed 100 watts. At this point, one of my batteries has a full SOC. Out of curiosity, I flipped on the Quattro inverter, and sure enough, the controller reports an increase in solar power.

If thats the case, then that would settle my first issue, but brings up another two other problems NOT related to the panels.

1) These batteries can accept 100A charge. Why has it taken a day and a half of clear weather with 2400 rated watts of solar to charge a 10.2kwh bank?

2) One of the batteries displays full SOC, the other displays 75% (3 of 4 LEDs). I have them hooked up to the lynx power in, the positive and negative 4/0 cables are the exact same length for both batteries. Why would the second battery not be charged, and why is the charge controller backing down the charge?

[Albatross]

It should be important to remember that we're only about a week out from the Winter solstice and the maximum solar declination in the Northern Hemisphere, which means that you're going to be seeing the minimum amount of solar your PV system should produce for the next couple of weeks before it starts to head up again. This is because the sun's rays are longer (in wavelength) because they're having to travel through more and more atmosphere to reach us because of the sun's position in relation to the tilt of the Earth's axis.

Of course, since you've only freshly hooked it up and flipped the switch, then it's probably more likely that you've missed a connection somewhere or something like that. Declination should really only account for about 5%-8% or so based on NC's latitude. There's also some issues of clipping the input and conversion losses that you'll experience, but what you're getting still seems low; despite these inefficiencies being cumulative instead of in-total. I think the most likely cause would be a missed connection somewhere. With a VOCmax of 49, hitting 80V-88V means that you're getting about the seasonal max for that series string, so you're probably just missing a string from the combiner.

[Albatross]

Originally Posted by RebelWithoutACausey

I think I may have a misunderstanding of the information in the victron app.

I just went back out at 1PM to check, and the app showed 100 watts. At this point, one of my batteries has a full SOC. Out of curiosity, I flipped on the Quattro inverter, and sure enough, the controller reports an increase in solar power.

If thats the case, then that would settle my first issue, but brings up another two other problems NOT related to the panels.

1) These batteries can accept 100A charge. Why has it taken a day and a half of clear weather with 2400 rated watts of solar to charge a 10.2kwh bank?

2) One of the batteries displays full SOC, the other displays 75% (3 of 4 LEDs). I have them hooked up to the lynx power in, the positive and negative 4/0 cables are the exact same length for both batteries. Why would the second battery not be charged, and why is the charge controller backing down the charge?

1) If your statement about having a 150/50 charge controller is accurate, then what your batteries can handle is irrelevant; because the charge is pushed from the charge controller instead of being drawn from the batteries like things being looked at from the load-side. Your 100A battery charge-rate capacity is twice the maximum charge-rate of a 150/50 system.

2) There's a number of reasons--again most likely suspect is a bad connection somewhere... But because it's also an electrical-chemical energy storage device, there could also be something up with the chemical condition of the battery. Victron, being a quality manufacturer of charge-controllers, can do what is known as an "equalizing charge", which works through some kind of dark black magic I don't completely understand. Essentially, it's able to tell if the battery is in a peak operating condition, and if it isn't, will do a special kind of charge/discharge rotation that 'shakes the crud loose', and can often keep the chemical components inside the battery operating at peak capacity. If your batteries have been sitting for some time, or they have different manufacture dates, then it is possible that this is what is happening, although there's often some kind of indicator showing what's happening.

[RebelWithoutACausey]

I typo’d in the OP, the charge controller can also push 100 amps. Its the 150/100.

Will the victron stuff automatically do its black magic or do I need to program it to do an equalizing charge?

[Albatross]

Originally Posted by RebelWithoutACausey

I typo’d in the OP, the charge controller can also push 100 amps. Its the 150/100.

Will the victron stuff automatically do its black magic or do I need to program it to do an equalizing charge?

Equalizing charges are normally done automatically by just about every charger I've ever seen--except for the most expensive ones with advanced controllers and usually large (desktop-sized) screens and lots of buttons.

Typically controllers will sometimes have a way of prompting to do one by your choice, but usually it's an automagic process when the controller detects that something is off with a battery.

[Booyah45828]

IDK

The battery maintainer I installed went up another amp(30w-44w) by putting the panel at a 45 vs being flat on the hood. This is with a 60 watt panel just a week ago and my correct angle for winter is 60°, which isn't so far from his 55°. I assume summer time the angle change vs flat won't gain me as much, but I was surprised by the increase I did see.

I guess I just assumed the loss/gain would be a similar percent between our setups, even with the size difference of the setups. Seeing he was about half his rating, which was similar to what I was at pre angle change. 30w/60w - 44w/60w ~ 1100w/2400w - 1800w/2400w. Or am I way out to lunch with my assumptions?

[Albatross]

Originally Posted by Booyah45828

IDK

The battery maintainer I installed went up another amp(30w-44w) by putting the panel at a 45 vs being flat on the hood. This is with a 60 watt panel just a week ago and my correct angle for winter is 60°, which isn't so far from his 55°. I assume summer time the angle change vs flat won't gain me as much, but I was surprised by the increase I did see.

I guess I just assumed the loss/gain would be a similar percent between our setups, even with the size difference of the setups. Seeing he was about half his rating, which was similar to what I was at pre angle change. 30w/60w - 44w/60w ~ 1100w/2400w - 1800w/2400w. Or am I way out to lunch with my assumptions?

Declination angle gets more extreme the further north you go, so your posted location of Ohio would see a more extreme decrease flat versus angled. Something else that actually makes a difference this time of year is that you can see an increase in power generation with a tilt due to increased light collection from diffraction from the snow. I'm not really sure how much of an increase you might see, but it's definitely something.

[nikitis]

I know you said you cleaned the panels with rain, but you need to make sure EVERY SQUARE INCH of those panels are crystal cleaned. You can literally put your hand over one of the squares inside of one panel and it will kill your wattage as a test. If even a single square isn't getting sun it can kill it. So ensure those panels are so clean you can lick them safely at every square inch of them. Then go from there.

[Ronnie]

Sun angle makes a huge difference. When the sun is directly at 90 to the panels versus 45 degrees to the panels is about a 50 % difference, at least in my experience. So a bright sunny day in winter, in Virginia I typically only see half of a what a sunny day in Florida will do in spring.

[Iceni John]

Enough hypothesising! Here's the facts of the matter: https://www.solarpaneltilt.com/

If your panels are flat, they'll produce tiddly-squat in the winter, especially at higher latitudes (except for crazy Alaskans who put their panels vertical in the bleak midwinter to catch reflected snow glare...). Instead of carpeting all my roof with a plethora of panels, I have only 2kW of them, but they're all easily adjustable from 21 degrees down (for travel) to 21, 33 or 45 degrees up for maximum solar harvest, even in the winter. I'm less interested about PV output in the summer than about what's possible in the winter, when every photon is precious. Unless you live in Quito, Kampala, Kisumu, Kiribati or Kalimantan, your panels shouldn't be flat!

John

[Danjo]

That’s what over-paneling is for.

I was in the Washington coast recently and there was a shuttle bus that had both the sides and top covered. Of course in the dark days of winter it’s not going to help anyway

[BriteLeaf]

Are you wired in series, parallel, or series/parallel?
It makes a difference.
Your charge controller should give you the maximum power ranges for 12/24/36/48 volts with the maximum watts that can come into the charge controller.
For example, I have 4 x 285 watt panels that I tried to wire them in series.
I was having issues until I wired two panels in series, and the other two panels in series, and those two are wired in parallel with each other.
I also wired my batteries in a 24 volt configuration using a 24 volt to 12 volt converter to take care of my 12 volt needs.