MPPT Charge Controller

rmaddy

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Ok guys I have the Victron MPPT hooked up. At this point I still have the panels hooked in parallel (12V).
If I hook my panels in series (24V) and I keep battery bank at 12V. Can I still run my potable 12V charger (When needed) to the battery bank without damaging the charge controller?
As has been mentioned a few times, you don't have 12V panels. The panel voltage and the battery voltage have almost nothing to do with each other when using an MPPT charge controller. You just need to make sure the resulting Vmp from the panel configuration is about 5V higher than your battery voltage so the SCC can actually charge your batteries.

When putting your panels in series the only real concern is making sure the resulting Voc, adjusted for the coldest temperatures, will not exceed the max input voltage of your controller. As has been pointed out in this thread already you can do 3S2P with your panels. Do not try 6S. The Voc may get over 150V in colder temps.

None of this affects your 12V battery or any loads connected to your 12V battery. The SCC will take whatever you give it from the panels and convert it your battery voltage for charging.

It's also fine to have multiple charge sources. You won't hurt the charge controller using a portable charger too.
 

Rednecktek

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None of this affects your 12V battery or any loads connected to your 12V battery. The SCC will take whatever you give it from the panels and convert it your battery voltage for charging.
The only thing you have to worry about as far as battery voltage is the amperage of your SCC. Your SCC can only handle so much panel based on your battery voltage X SCC amperage. I.E. if you had a 60a SCC at 12v you can only utilize 720w of panel. If you had a 30a SCC you could only use 360w of panel.
 

rmaddy

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The only thing you have to worry about as far as battery voltage is the amperage of your SCC. Your SCC can only handle so much panel based on your battery voltage X SCC amperage. I.E. if you had a 60a SCC at 12v you can only utilize 720w of panel. If you had a 30a SCC you could only use 360w of panel.
Yes, but the all of that was already beaten to death earlier in this thread.
 

Barridge

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Thank you guys! This is the beginning of my conversion 12v to 24v. Inverter will be next. Then I want to increase my battery bank.
 

MisterSandals

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Can I still run my potable 12V charger (When needed) to the battery bank without damaging the charge controller?
Yes, they will both be 12V chargers. The MPPT takes the higher input voltage and produces the desired battery charge voltage so thinking in marketing terms "12V panel and 24V panel" is not applicable.
 

MisterSandals

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This is the beginning of my conversion 12v to 24v. Inverter will be next. Then I want to increase my battery bank.
Wait what?
You cannot just change "your system" from 12V to 24V. SCC's usually handle either 12.8V or 25.6V but inverters are almost always designed for one or the other and cannot have their operating voltage changed. Batteries/cells of course can be connected/configured in different ways to achieve different voltages.
 

Barridge

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Well your VoC is 22.4v so with your 2s/3p setup you're running 44.8v and 28a to your controller. Even if you rewired it up to be a 3s/2p setup you're still well within the voltage range of pretty much any decent MPPT controller. The only issue is that most controllers are limited on how much panel they can use for a given voltage based on the amperage rating of the controller and the voltage.

For example, say you picked up a 60a EPEver or PowMr or something controller. The 60a is what the controller can pump out to your batteries, so if you had it connected to a 12v system, that would be 60a X 12v = 720w. On the same controller running the 24v system you would get 60a X 24v = 1440w. So on a 12v system you're over paneled (which is fine because reality and data plates are 2 different things) and on a 24v system a little under paneled (which again is fine as you're not trying to do a full charge in 1 hour) so either way you're good to go.

MPPT controllers like having higher voltages to play with but all that really matters (unless you're trying to eke every single watt possible) is that your VoC is a few volts higher than your battery bank voltage.

As for which one to go with, the cost difference between a 40a and a 60a is so small you might as well go larger to give you more expansion room in the future. Over 60a they tend to get more expensive per amp so IMHO the 60a SCC's are the sweet spot. EPEver, Victron, BougeRV, all sorts of good brands. Ones to avoid would be Renology, EcoWorthy, or MakeSky. Find ones that fit your budget with the most amperage rating available and any features (bluetooth, wifi, disco balls, etc) that you want and has good ratings, and go for it.

Also, there's really no such thing as a "12v panel" or a "24v panel" it's just a marketing term that lets you know what kind of battery bank you could theoretically charge with it. A "12v panel" would charge a 12v battery, but wouldn't produce enough voltage to feed a 24v battery. The VoC is the actual numbers you want to use when calculating for arrays and controllers. :)
I did purchase Victron 150/70 SCC. I hooked up my 6 panels in series. With 2 panels going to 1 circuit breaker in my 3 position combiner box.
(Other 4 going to the other 2 breakers)
I am finding that my agm batteries are getting old and are not holding a charge like they once did.
This time of year is rough in the Adirondacks. Cloudy days 95% of the time.
So I was going to go with a 24v inverter and buy 4 new agm's (230amphr each).
I would like to buy 2 more 150w panels to match the other 6. Giving me 8 all together.
Would I see better results if I hook my panels in series of 4 panels (48v) to 1 circuit breaker? The other 4 to another circuit breaker.
What do you suggest?
Thank you for your help!
Or should I purchase a larger combiner box?
 

MisterSandals

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Panel Voc is 22.41V
4 in series = 89.64V

The amps will be low enough that you could really connect each string in parallel with a Y connector and use a single breaker. But each 4S string to its own breaker works too. Are you combining them before your SCC(s)?
 

rmaddy

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I did purchase Victron 150/70 SCC. I hooked up my 6 panels in series. With 2 panels going to 1 circuit breaker in my 3 position combiner box.
(Other 4 going to the other 2 breakers)
6 panels in series wouldn't use a combiner box. It sounds more like you might have your 6 panels in 2S3P, not 6S. Can you verify the actual setup?

As I stated in post #42 above you do not want your panels in 6S because you can easily exceed the 150V limit in colder weather.

If you get 2 more and then wire the 8 panels in 4S2P then you do not need a combiner box or the breakers. But it doesn't hurt to do so.
 

Barridge

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Panel Voc is 22.41V
4 in series = 89.64V

The amps will be low enough that you could really connect each string in parallel with a Y connector and use a single breaker. But each 4S string to its own breaker works too. Are you combining them before your SCC(s)?
Yes before the SCC.....
 

Barridge

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6 panels in series wouldn't use a combiner box. It sounds more like you might have your 6 panels in 2S3P, not 6S. Can you verify the actual setup?

As I stated in post #42 above you do not want your panels in 6S because you can easily exceed the 150V limit in colder weather.

If you get 2 more and then wire the 8 panels in 4S2P then you do not need a combiner box or the breakers. But it doesn't hurt to do so.
Yes I believe I understand the lingo! 2S3P meaning 2 panels are connected + to - (series), leading into breaker #1 in (parallel) and I have 3 breakers in my combiner box before my SCC.
 
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