Solar Charge Controller recommendation

[Lioncat55]

I am building a system for my camping trailer and I am having a hard time finding out what charge controller to use. I want a 24v system as I will have a small fridge and will use 24v to 12 dc to dc when needed. I am going to use the panel pictured below and two of the batteries pictured below. I am trying to keep the cost down, any help on what charge controller to use and what specs I need would be a lot of help.

 

[MisterSandals]

I want a 24v system as I will have a small fridge

Does your small fridge run on 24v? Those are pretty rare. Otherwise, this is an odd consideration for making a 24v system.

 

[Lioncat55]

Does your small fridge run on 24v? Those are pretty rare. Otherwise, this is an odd consideration for making a 24v system.

I am looking at a small one like this and it seem to run on 12v and 24v.

https://www.amazon.com/dp/B07WFHRSBZ/

 

[gnubie]

Higher voltage panels, I'd put them in parallel. The Vmp is high enough to work OK with a MPPT controller. That would let you use any number of MPPT controllers, epever, renogy (SRNE) etc. Most of the controllers in the around 1kW capacity are rated up to 100V max PV Voc. A '40 amp' model would do the job. If you have a look around and post a link to a controller that interests you someone will be able to yay / nay it.

 

[MisterSandals]

Looks reasonable. If its not too much of a hassle to convert to 12v for your other items this looks good.

Your panels having a Voc of 47.4 would likely need an SCC that will handle in excess of 100v if running these in series due to thermal properties when cooled below the rated 25 deg C (something like .4v per deg C, should be listed on your panel).

 

[Lioncat55]

I'd put them in parallel.

I am only planning on one of those panels as it's a small trailer, about 94.5" x 78.5".

Would this controller work? https://www.ebay.com/itm/353095914075

Thank you for all the help so far as I am still leaning all this stuff.

 

[MisterSandals]

I know you're trying to keep costs down and looking at a cheap SCC may seem like its doing that initially. But, you really don't want to cheap out on an SCC more than about anything else, including personal safety.

I gotta recommend a Victron 100/20 (slightly larger than you need but will run easily for what you are doing).

Amazon.com : Victron Energy SmartSolar MPPT 100V 20 amp 12/24/48-Volt Solar Charge Controller (Bluetooth) : Garden & Outdoor

Amazon.com : Victron Energy SmartSolar MPPT 100V 20 amp 12/24/48-Volt Solar Charge Controller (Bluetooth) : Garden & Outdoor

www.amazon.com

Also the Victron 75/15

Amazon.com: Victron BlueSolar 75/15 MPPT Charge Controller - 15 Amps / 75 Volts: Electronics

Amazon.com: Victron BlueSolar 75/15 MPPT Charge Controller - 15 Amps / 75 Volts: Electronics

www.amazon.com

I STRONGLY recommend spending the extra $25 to get the Bluetooth model. It will make upgrading firmware, setting up the SCC and monitoring it a joy. I have a 100/30 and am amazed how well that works and how easy it makes doing everything. And with a 5 year warranty, its peace of mind that this will serve you for a long time.

 

[gnubie]

I am only planning on one of those panels as it's a small trailer, about 94.5" x 78.5".

Would this controller work? https://www.ebay.com/itm/353095914075

Thank you for all the help so far as I am still leaning all this stuff.

Avoid anything PowMr, they are knock off cloners. It's a PWM design too, best to avoid those designs too if you can.

 

[Lioncat55]

Would this one work then? Looks to have Bluetooth built in, but is the less expensive 75/15.

Amazon.com: Victron Energy SmartSolar MPPT 75V 15 amp 12/24-Volt Solar Charge Controller (Bluetooth): Industrial & Scientific

Buy Victron Energy SmartSolar MPPT 75V 15 amp 12/24-Volt Solar Charge Controller (Bluetooth): Energy Controllers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[MrNatural22]

Or this Epever 30a MPPT with included accessories in the same price range. The 40a version is only $18 more.

Amazon.com: EPEVER 30A MPPT Solar Charge Controller 12/24VDC Automatically Identifying System Voltage with MT50 Remote Meter & Temperature Sensor RTS & RS485 Cable

Amazon.com: EPEVER 30A MPPT Solar Charge Controller 12/24VDC Automatically Identifying System Voltage with MT50 Remote Meter & Temperature Sensor RTS & RS485 Cable

www.amazon.com

 

[Lioncat55]

As a newb question, what does the AMP rating mean on the controller?

 

[MrNatural22]

That’s the max charge the CC can output to the battery.

 

[MisterSandals]

Since your setup will be 24v, that makes your charge current to be...

(370w x (.8 effieiency/reality?)) / 24v = 12.33amps

 

[Forbisher]

I am building a system for my camping trailer and I am having a hard time finding out what charge controller to use. I want a 24v system as I will have a small fridge and will use 24v to 12 dc to dc when needed. I am going to use the panel pictured below and two of the batteries pictured below. I am trying to keep the cost down, any help on what charge controller to use and what specs I need would be a lot of help.

I have 12V - 24V. / 120V fridges and do not see any great advantage of making your small 370W panel system 24 volt 65Ah battery on a small camper.
You can use smaller wire but the lengths must be not that long anyway.
Why not go with 12 volts?
My 45 litre 12V fridge uses 10 watts hour on 12 volts.
Are you using an inverter in the system?

 

[Lioncat55]

I have 12V - 24V. / 120V fridges and do not see any great advantage of making your small 370W panel system 24 volt 65Ah battery on a small camper.
You can use smaller wire but the lengths must be not that long anyway.
Why not go with 12 volts?
My 45 litre 12V fridge uses 10 watts hour on 12 volts.
Are you using an inverter in the system?

My thought was a little easier to wire and it should be more efficient. I was planning on adding an inverter, and now that you mention it. a high enough amperage 24v to 12v dc to dc converter might be more than it's worth.

Would the Victron SmartSolar MPPT 75/15 SCC still be a good pick if I am going to run the battery's in parallel and keep them at 12v?

 

[Fallingaway]

I agree. 24volts seems overkill just to run a special fridge and everything else is 12v.

 

[Lioncat55]

If I am understanding the datasheet correctly, if I do a 12v system, the 75/15 controller can only make use of 220w from the (up to) 370 watts the panel is rated for. Would that be the reason to go with the EPEVER 30A as it can support up to 390W at 12v?

 

[Forbisher]

I agree. 24volts seems overkill just to run a special fridge and everything else is 12v.

Those kind of fridges are 12 to 24V so nothing special about them. Most are 120V too but the latest Iceco YD42 I am getting anyday is DC only with a 120V power brick.

 

[Fallingaway]

Regardless. The point was that making a 24v system just for 1 appliance and having to convert it back

If I am understanding the datasheet correctly, if I do a 12v system, the 75/15 controller can only make use of 220w from the (up to) 370 watts the panel is rated for. Would that be the reason to go with the EPEVER 30A as it can support up to 390W at 12v?

yes. Laying that flat on your camper roof, your not going to get close to the max output of that panel anyway. I bet you’ll only get a little over half for 90% of the time the sun is out.

 

[Lioncat55]

Regardless. The point was that making a 24v system just for 1 appliance and having to convert it back

yes. Laying that flat on your camper roof, your not going to get close to the max output of that panel anyway. I bet you’ll only get a little over half for 90% of the time the sun is out.

Sounds like making a way to tilt it is a must.

Thank you for all the help.