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Over panel risk?

gray webber

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Feb 4, 2022
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While I understand much of the solar issues, some component ratings do not compute for this newbie. I have been introduced to the term over-paneling. While this May seam easy to understand as to charge controllers, the manufactures only state max watts for a battery bank voltage.
My question: Will a charge controller be damaged if you feed more panel watts into them then rating or is their max rating the most they will convert into useful charging?
If they are not damaged then overpaneling May be good for cloudy regions that need extra PV for lean times.
I hope I explained my question right?
Thanks!
 
their max rating the most they will convert into useful charging?
Exactly. If your panels produce more than the batteries can take, the SCC will just reduce the amperage. It's very normal for this to happen anyways when the batteries are full. We call that "Clipping"
If they are not damaged then overpaneling May be good for cloudy regions that need extra PV for lean times.
That's the benefit to overpaneling. When winter hits you need more panel to charge your batteries up. Remember that the wattage rating of a panel is under perfect lab conditions and you'll very rarely ever see it in real life.

Another benefit to overpaneling is to spread your array. Say you had a 3s3p setup. You can face a string SE to catch a better angle on the morning sun, a string due south for good mid-day light, and a panel SW to catch the rays from the afternoon sun. While your SCC may be way under specced for 9 panels, only 3 of them are really making BigWatts at any given time.

The big, and I mean ZOMGHUGE!!! thing is to NEVER EVER over-volt your SCC. It can cut off the amperage if the batteries don't need it, but it can't clip the voltage the panels are producing and you can end up with magic orange smoke/fire/angry wife. :oops:
 
Great info Sir!
So if I have 3200 watts(No over volts) fed into my CC that’s rated at 2400 then my controller is safe? The rating speaks to the max the CC can convert not the max you can connect?
I hope I have this right as I’m in one of those snow zones where for three days at a time we can expect as little as 10% of our panels output. If I bulk up my panels then 10% of 3200 beats 10% of 2400:). Thus my need for generator is much reduced or eliminated. Cheaper and more reliable to have a few extra panels then to purchase, install and care for a generator!
Thanks again for sharing!
 
they are not damaged then overpaneling May be good for cloudy regions that need extra PV for lean times.
Don’t over-voltage the charge controller. Look up and read the information about using the temperature coefficient to calculate the maximum voltage. Panel voltage goes up significantly the colder it gets, so you need to account for that.

Over paneling in series with mppt charge controllers can also get you charging earlier and keep making some charge later in the day even if no clouds. Over paneling will usually exceed your harvest ability mid-day because more watts are available than the charge controller can deliver but you’re not losing anything: you simply are getting everything you can.

One thing I did was have two arrays- one faces SE, one faces SW. This combined with over paneling will usually reduce midday watts available but since you’d be not harvesting some watts by over paneling anyways, you don’t really lose anything PLUS you spread harvest over a longer portion of the day. Depending on region and other factors this may net you more storable watts and usually should keep your batteries fully charged much closer to sunset.

Just some ancillary information to get your mind’s lens seeing this in more dimensions.
 
I’m in one of those snow zones where for three days at a time we can expect as little as 10% of our panels output. If I bulk up my panels then 10% of 3200 beats 10% of 2400
You got it!
Cheaper and more reliable to have a few extra panels then to purchase, install and care for a generator!
Absolutely. Here in Vermont I have many of those periods but it’s mostly a problem in winter due to furnace fan.
 
Not all SCC's are created equally either though. While overpaneling is suggested by many, some SCC's can only handle so much. Best to post the model number of the SCC and specs of the panels so that we can help determine a safe range before just going for it.

High quality SCC's such as Victron, EPEver etc, can be overpaneled sometimes double their rated capacity. While there are others that can only be overpaneled by a couple amps.
 
Not all SCC's are created equally either though. While overpaneling is suggested by many, some SCC's can only handle so much. Best to post the model number of the SCC and specs of the panels so that we can help determine a safe range before just going for it.

High quality SCC's such as Victron, EPEver etc, can be overpaneled sometimes double their rated capacity. While there are others that can only be overpaneled by a couple amps.
Good to know! I have a Midnite solar classic 150 SCC. It has up to 94 A with 24 volt system. I have 4 - bi-facial rated at 445 watts but in trial runs I have gotten from 508 to 618 watts and became concerned my SCC was threatened? Also, I may want to add panels for the bad times and needed to know if this was a no go or what.
 
A friend is checking out my solar system activity and has plans to install an Off grid for his calm about a mile back in. I wander if the Growatt 3000 would handle over panelling as he is looking at it. It would be a low cost system core. My Victron Multiplus is nice but pricy. Also it has no SCC within so that really jacks the cost. I was concerned about the stand by power needs of the Growatt as I can get my Vic to as low as 4W if I need to. It is now at 27W. I need to learn more before trying to change settings as It was programmed for me and I do not want to change the DIP switch setting till I know if that will over ride my lithium charge settings?
 
wander if the Growatt 3000 would handle over panelling as he is looking at it
(Edited)
From their website. It can deliver 80A of solar charge which is wildhat guessing about the 2000W it mentions guessing for inefficiencies.
don’t overvolt it. 77*F volts will go way up at 10*F so you need to go to a temperature coefficient calculator online and make sure you don’t crowd the 145V

EDIT
FilterGuy document on over paneling says that the 1500W panel watts version cannot be over paneled do one might assume the same for the data sheet model I posted.

6F0A7F81-63D5-4F98-9FBC-01DD3F40AB04.jpeg
 
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I have max of 88volts in the strings.
The manual says 94amps or 2700 watts? Should be ok. Just can’t add anything?
 
I have two Midnite Classic 150's feeding a 45 kWh battery system, each of the 150's is hooked to 4.5 kw of panels. At 24 volts, that's the potential for about twice what they are rated for. I do this because I live in a dark, cloudy, rainy place and I need all the panels I can get for 3 months of the year. Days like today, the batteries are low after several days of clouds and the 150's have been running maxed out for the last 4 hours. I reduce the maximum output from 94 to 85 amps, it brings the temperatures down about 10 degrees without significant loss of power, the temperatures stay well within the safe range for the controllers, and they'll run at that 85 amps all day without issue.

The Classics regulate their output to a safe level, and will reduce it even further if temperatures get high, they're well built. Some controllers probably aren't so well protected and there might be an issue, but for any of the better ones they only accept what they can handle.
 
Hopefully you have used the MidNite sizing tool and are aware of the effect of very cold temps on voltage produced by solar panels. There is a link to the tool in my signature. You are fortunate to have the HyperVOC feature.
I have found the folks at MidNite to be very helpful on the phone, you know actually talking.

My Charge Controller is NOT a MidNite and I think it clearly states in Chinglish not to exceed 1600 watts which is 200 watts above the 1400 recommended.

Maybe you could put some of your "overpaneling" on a breaker at a combiner box. That would make it easy to disconnect them when the sun shines bright. Good luck remembering to switch them off & on.

Really good info prior to my post. Point some panels this way, some that way. No OVERVOLTAGE.
 
I have two Midnite Classic 150's feeding a 45 kWh battery system, each of the 150's is hooked to 4.5 kw of panels. At 24 volts, that's the potential for about twice what they are rated for. I do this because I live in a dark, cloudy, rainy place and I need all the panels I can get for 3 months of the year. Days like today, the batteries are low after several days of clouds and the 150's have been running maxed out for the last 4 hours. I reduce the maximum output from 94 to 85 amps, it brings the temperatures down about 10 degrees without significant loss of power, the temperatures stay well within the safe range for the controllers, and they'll run at that 85 amps all day without issue.

The Classics regulate their output to a safe level, and will reduce it even further if temperatures get high, they're well built. Some controllers probably aren't so well protected and there might be an issue, but for any of the better ones they only accept what they can handle.
Really great to hear! I don’t need to worry about my SCC. In fact-I’m in a zone like you. Second day of near zero sun charge.. tomorrow expected to be the same. Given your info, I should be able to add a panel to each string thus going to about 40% over rating for bad sun days. May dial back the max charge if I can figure out how that’s done?
I’m going to check my Voc but with one more panel per string if I connect in series I get 146.9 v at 20c so at cold temps like -20c it would exceed the 150 volt cap. Operating volts with 2-in series is about 90v.
This means 3 sets of 2 in series running at 90volts and short circuit of 15a or 2 sets of 3 in parallel running at 42 volts and 45 a.
Other option is two stand alone panels on a second SCC?
 
I ran the numbers in the Midnite Solar work sheet at the projected 30% added Bi-facial outputs and the SCC just made it. One caveat is the panels have already produced 40% over in a real world test run—-cold sunny day. I’ll attach photos of each.
Thoughts? View attachment 84880D1AA14B2-5461-4FE5-AB47-C8AC27EAAFDD.jpeg832BA6D7-634C-4FF1-ACAA-20CD753A9B27.png
 
I ran the numbers in the Midnite Solar work sheet at the projected 30% added Bi-facial outputs and the SCC just made it. One caveat is the panels have already produced 40% over in a real world test run—-cold sunny day. I’ll attach photos of each.
Thoughts?

Nice to see you used -30C. A little fudge factor to account for freak weather. (y)

Are the coefficient numbers MidNite's default numbers or yours?
 
While I understand much of the solar issues, some component ratings do not compute for this newbie. I have been introduced to the term over-paneling. While this May seam easy to understand as to charge controllers, the manufactures only state max watts for a battery bank voltage.
My question: Will a charge controller be damaged if you feed more panel watts into them then rating or is their max rating the most they will convert into useful charging?
If they are not damaged then overpaneling May be good for cloudy regions that need extra PV for lean times.
I hope I explained my question right?
Thanks!
I'd just purchase another SCC rather than overpanel just one and expect it to clip the amps.

But I look at things a little different than most........
 
I have two Midnite Classic 150's feeding a 45 kWh battery system, each of the 150's is hooked to 4.5 kw of panels. At 24 volts, that's the potential for about twice what they are rated for. I do this because I live in a dark, cloudy, rainy place and I need all the panels I can get for 3 months of the year. Days like today, the batteries are low after several days of clouds and the 150's have been running maxed out for the last 4 hours. I reduce the maximum output from 94 to 85 amps, it brings the temperatures down about 10 degrees without significant loss of power, the temperatures stay well within the safe range for the controllers, and they'll run at that 85 amps all day without issue.

The Classics regulate their output to a safe level, and will reduce it even further if temperatures get high, they're well built. Some controllers probably aren't so well protected and there might be an issue, but for any of the better ones they only accept what they can handle.
A question to you who has experience with over paneling Midnight Classics. I have two series strings paralleled into 2400 watts. Will a third string totaling 3600 watts be ok for the SCC? I’m thinking of near vertical winter position to minimize snow cover. A third set would improve bad weather power. No real sun here for three days of blizzard.
 
I built a solar generator out of a rolling toolbox and an Amperetime 24v 200Ah battery at its heart. Unfortunately, before I was wiser I opted to use the Renogy Rover 40 Li as the SCC. They say to not run over 1040 watts for 24v in the manual. I have 6 250 watt, used, panels. I know that the Renogy isn’t the most robust controller, should I follow the manual to the letter or will facing 3 strings SE/S/SW be ok? If it’s not I’ll just have to run the 2 strings, which will probably be ok, but obviously I’d like to be running as much input as possible.
 
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