MPPT Charge Controller

Barridge

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Is it possible use a MPPT charge controller and have my panels hooked in series to make 24V and keep my batteries at 12V?
 

Rednecktek

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Yes, the charge controller should auto-detect the battery voltage and set itself for that. The panels can be any voltage up to the limit of the controller and it will do it's own magic and convert that to the 12v system.

You'll probably get a bit more power through the day by doing the series runs too as it will be able to harvest power in lower light conditions like morning and evening. It's really a Win-Win. :)
 

rmaddy

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Make sure the combined Voc of your panels in series, adjusted for the coldest temperatures your panels will experience, will not exceed the max input voltage of the charge controller.
 

Barridge

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Thank you. That's what I'm working on now.
I'm looking to purchase a MPPT Charge Controller to run my 24V solar to my 12v Batteries.
Then in a while buy a 24V inverter and switch the whole system to 24V.
I have 6 150W 12V Panels. 2 panels on each string and 3 strings.
Do you have any recommendations for a quality MPPT controller?:)
 

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Rednecktek

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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. :)
 
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Hedges

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Thank you. That's what I'm working on now.
I'm looking to purchase a MPPT Charge Controller to run my 24V solar to my 12v Batteries.
Then in a while buy a 24V inverter and switch the whole system to 24V.
I have 6 150W 12V Panels. 2 panels on each string and 3 strings.
Do you have any recommendations for a quality MPPT controller?:)

"24V" nominal of PV may be marginal to charge a 24V battery with MPPT. Typically a bit of headroom is needed, and PV voltage drops on a hot day and with less sun. "36V" nominal will probably work better, deliver more Wh/day. So buy an SCC with high enough voltage input to tolerate the Voc of 3 panels in series (3s2p as RedNeck suggests), +20% extra for cold weather, 80.7V. So get one that accepts 100V or more.
 

Barridge

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Hey guys thank you for help. I was going to do this a few years ago but decided it was working so let well enough alone.
But now my SCC starting to hum on sunny days so I am anticipating trouble ahead. So thanks again!
I'm going to look at EPEver, Victron, BougeRV. The ones RedNeck suggested.
 

MisterSandals

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I'm going to look at EPEver, Victron, BougeRV. The ones RedNeck suggested.
The SCC is the heart and brains of a solar system. Money invested in a quality SCC, like Victron, is the way to go. I REALLY like the idea of a 5 yr warranty and great Bluetooth setup, monitoring and firmware updates.
 

Rednecktek

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Personally I prefer the mid-range units like the EPEver's and HQST and such, although my current two are the PowMr's because I didn't know better at the time and I was on a budget. They're working so far but I bought a HQST for my next project since I needed a little one anyways. I've just never seen what a $700 SCC gets me that I need that a $200 model doesn't. YMMV.
 

MisterSandals

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I've just never seen what a $700 SCC gets me that I need that a $200 model doesn't.
Just out of curiosity, what $700 SCC is replaced by a mid-range $200 SCC? Happen to have specific make/models that fit this scenario?

If there is an equivalent at 28% of the price, I am interested!
 

Rednecktek

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Well, let's see what a 60a controller runs roughly:
Morningstar 60A is just shy of $700
Victron Tr250 is about $640
Victron Tr150 is about $400
Midnite Solar MNMPPT60DIY is a good higher-mid range price at $435
MPP Solar PCM60x is a bit pricy at $300
EPEver 60a is about $230 and is a very respected brand

If you're on a budget:

PowMr 60a for an even Benjamin ($100) is the ones I'm using currently and are lith programmable
60AMP-EM2460 With WiFi for $170gives you a internet accessible option

Yes, the Victrons have a few features more than anyone else does, but I personally have no need of Bluetooth or WiFi at an off-grid cabin or a tool shed.

And that doesn't even get into things like the AIO's from MPP or Growatt or the like.

Tl;Dr: Find the one with the features and price range you want and go with that one.
 
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Hedges

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Midnight Classic 250, 63A $1050
Classic 150 is 96A $925


MSTE Sunny Island Charger 50A is 600 GBP ($800)
 

rmaddy

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That's not a fair list. Based on earlier posts it seems a 100V, 40A - 60A SCC would be appropriate. So why list a 250V Victron? Victron has the 100/50 which would support 100V and output 50A. That's $323.
 

Rednecktek

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That's not a fair list. Based on earlier posts it seems a 100V, 40A - 60A SCC would be appropriate. So why list a 250V Victron? Victron has the 100/50 which would support 100V and output 50A. That's $323.

The Victron is listed as a 60a SCC, and I was trying to get a broad comparison of 60a units as a rough reference line.
 

Barridge

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Thank you guys for all your help! Right now I am leaning towards the Victron 150/60 because the size of the unit will fit into the space I have.
I like the warranty.
So Far eBay has the best price I can find. $491.30
 
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rmaddy

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Once you are at 24V you can use your 6 150W panels in 3S2P using a Victron 100/30. That will take full advantage of about 800W of your 900W panels. The 100/30 is a lot cheaper than the 150/60 but the 100/30 will only let you use about 400W while you are at a 12V setup.
 
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