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Old 01-04-2019, 01:11 PM   #1
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Lets Talk Charge Controllers

So I have a 2450w solar array and need a MPPT to match. Any recommendations on compatible units.

Looking at this one, but open to options.
https://www.ebay.com/itm/Renogy-Rove...Wvrf:rk:8:pf:0

Midnight Classic makes a nice unit, but are they worth the extra $300+
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Old 01-04-2019, 01:51 PM   #2
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I have the midnite classic 200. I have not had a single issue so far. Solar has been up and running for about 4 months. It's built really solid. I don't have any experience with the renogy controllers.
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Old 01-04-2019, 01:57 PM   #3
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Also, I'm sure you've seen this, but if not

http://www.midnitesolar.com/sizingTool/
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Old 01-04-2019, 02:05 PM   #4
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I read reviews on the top 10 Charge Controllers for 2019. Such a wide range of pricing. As low as $39 and then the Midnight Classics that run $700+. Are any of the more expensive ones any better on ROI than the others?
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Old 01-04-2019, 02:25 PM   #5
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Panel specs? Configuration?

Battery voltage? If you are thinking 12 volt you will be limited to about 1000watts with the Classic. You can overpanel to some extent but are limited to 79 amps. Nominal voltage is actually 13.8v. So....

13.8v x 79a = 1090watts

You might get away with using that controller with 2400watts of panels if you go with a 24 volt battery.


Victron makes a controller that is rated for 100 amps on a 12 volt system. That would get you closer.

I have done quite a bit of looking and have not been able to find a controller that is rated for more than 100 amps and still support a 12 volt battery. The higher rated units, that I have found, don't support 12 volt. Only 24v-96v and they are quite expensive.

The folks over on solarpaneltalk have some great info on solar system sizing and design. Lots of informative stickies including my favorite: https://www.solarpaneltalk.com/forum...-size-tutorial
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Old 01-04-2019, 02:36 PM   #6
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You could break up your array into two and run two charge controllers and get 158a-200a of charge capacity.

If you have 200a charge capability at 12v then you will need roughly a 2000a/h battery bank. You could run six of these in series : 2 YS 27P | Rolls Battery

Unfortunately that is about 1500 lbs of batteries.... And they cost around $1000 each....

Another option would be to configure your charge controller to limit charge current to protect your batteries from boiling and go with a more modest battery bank. But... If you are going to tell the controller to only use a portion of the panels then why put more up there?

Gotta give it to you Marc. You think big.
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Old 01-04-2019, 02:48 PM   #7
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Originally Posted by PNW_Steve View Post
You could break up your array into two and run two charge controllers and get 158a-200a of charge capacity.

If you have 200a charge capability at 12v then you will need roughly a 2000a/h battery bank. You could run six of these in series : 2 YS 27P | Rolls Battery

Unfortunately that is about 1500 lbs of batteries.... And they cost around $1000 each....

Gotta give it to you Marc. You think big.
Ya, $830ea, $5000. Am I thinking too big?
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Old 01-04-2019, 05:33 PM   #8
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Ya, $830ea, $5000. Am I thinking too big?
I wish I could remember where I read it, someone made a comparison using a car. The engine is your load, the gas tank is the batteries and the gas pump is the solar.

The engine runs from the gas in the tank. When the tank gets low you refill the tank from the gas pump.

Loads run from the battery and the battery gets refilled when the sun shines.

System design generally goes:

Identify loads
Spec inverter and battery to support those loads.
Spec panels and charge controller to fit battery and local conditions (solar insulation)

Sometimes we have to compromise ideal design because of budget or physical limitations.

I do think that 2400+ watts is a bit overkill in this application. Primarily because of battery challenges. Weight, space and cost.

Lately solar panels have dropped significantly in price. Unfortunately the components that go along with them have not.

I will be spending 1/3 of my "solar budget" on panels and 2/3 on batteries, charge controller and materials. This does not include inverter.
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Old 01-04-2019, 05:41 PM   #9
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I have eight Sharp 255W panels totaling 2040W, and because each group of four are separately tiltable I've split them into two completely separate groups. Each group of four powers a Morningstar TS-MPPT-60 which in turn charges four golfcart batteries in series and parallel, in other words I have two entirely separate systems running in parallel. Even if Something Bad were to happen to one panel, or one group of panels, or one CC, or one battery, or one bank of batteries, at worst I would lose at most only 50% of my total power. Redundancy is good!

You may want to use a CC (or two) that doesn't rely on fans for cooling. Fans are always the first things to fail, and in a potentially dusty environment they'll suck gritty dust into the CC's interior. No bueno.

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Old 01-04-2019, 06:27 PM   #10
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Okay, 2400 is overkill, I can cut down the quantity of panels. Where should I start for the next piece of the equation. I know asking for averages is subjective, but for a normal Skoolie what would be the requirements? Wiring the electric is not an issue for me, solar is totally greek to me still.
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