Charge Controller Sizing / Panel / Array wiring

Hi All -
I am new to the 12V side of solar for my RV, cant stand the generator. So what I have so far is four (4) 275w panels ( 38.6 Voc, 31.50 Vmp, 8.74 Ipm), a 2000w Inverter charger, and three (3) 150ah / 12V AGM telecom batteries ( I have the ability to get more should I want) and of course all of the necessary wiring etc ... My last piece of the puzzle is a charge controller and how to wire up the panels.
I have been looking towards the Midnite Solar charge controllers as I think @ 12v I'm pushing into high wattage territory. I have outback controllers in the house and like them but am thinking the Midnite Solar may fit this use case better.
Are there any charge controllers I am overlooking ?
Does anyone have any thoughts ? Insight would be greatly appreciated.
I am new to the 12V side of solar for my RV, cant stand the generator. So what I have so far is four (4) 275w panels ( 38.6 Voc, 31.50 Vmp, 8.74 Ipm), a 2000w Inverter charger, and three (3) 150ah / 12V AGM telecom batteries ( I have the ability to get more should I want) and of course all of the necessary wiring etc ... My last piece of the puzzle is a charge controller and how to wire up the panels.
I have been looking towards the Midnite Solar charge controllers as I think @ 12v I'm pushing into high wattage territory. I have outback controllers in the house and like them but am thinking the Midnite Solar may fit this use case better.
Are there any charge controllers I am overlooking ?
Does anyone have any thoughts ? Insight would be greatly appreciated.
Comments
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
1100 watts of panels will only put out about 75% of their panel rating in normal every day conditions. If you look for a spec sheet .pdf for your panels look for the Normal Operating Cell Temperature Values, NOCT values. These will be roughly 75% of the name plate value. Also even if you allow your battery to go down to 50% state of charge, or about 12 volts, you need a voltage about 10% higher than that to effectively charge the battery bank.
So the math looks more like 1100 watts x 75% to arrive at NOCT value = 825 watts / 13 volts = @63.5 amps
While I like the Midnite classic and use them at home, they do have internal fans to cool the electronics. For a Camper, I'd suggest a Morning Star TS 60 MPPT. It has no internal fan and used large cooling fins instead. You might be slightly over paneled for it, but that is not bad at all.
https://www.solar-electric.com/motr60ampmps.html
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
edit: I'm going to go make sure, but I may have forgotten some of the better/more expensive Morningstars.
Two MPPT controllers cannot share the same array, but can feed into a common battery as long as the settings are the same and wired/fused independently to prevent conflict. Even two controllers from different manufacturers would work, again settings the same, or very close. Some systems as you say can communicate which is a good feature but not absolutely necessary.
https://www.morningstarcorp.com/parallel-charging-using-multiple-controllers-separate-pv-arrays/
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,
Next is thoughts on panel wiring, thoughts anyone ? I was thinking series, is there any reason, maybe redundancy, I should not just wire all four panels in one string ?
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,
Generally the higher the incoming voltage the harder the controller must work. Usually the sweet spot is about 2x the system voltage. If you have more than 2 strings you would normally want a combiner box. I would do 4 panels as 2 sets of 2 in series, and use branch connectors to combine them on the roof and just bring 2 wires to the charge controller.
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,
> Next is thoughts on panel wiring, thoughts anyone ? I was thinking series, is there any reason, maybe redundancy, I should not just wire all four panels in one string ?
Two reasons:
- As mentioned, all in one string could be pushing voltage limitations in the controller.
- Especially in a mobile application, shade could be an issue. With a series string, even minor shading (like a nearby overhead wire) can severely limit output for the entire string. In parallel, only the shaded panels (string) is affected. Also, in a mobile application, distances from pv to controller tend to be short, so the cost of using heavier wire to carry higher currents in parallel tends to be low.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Gives you a solar array with:
2xVmp
2xImp
Bill
1.2KW off grid system; 2 strings of 2ea 305W 60 cell panels on a redneck ground mount; MNPV3 combiner feeds a MN Classic 150 located 100' away; 12V 460AH FLA battery bank powers a cabin-wide 12V DC system as well as a Cotek 700W PSW inverter; Honda EU2000i and IOTA 55A charger bridge cloudy days and a Champion 3800W generator for short duration, power hungry appliances.
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Most people will have very short runs out of the charge controller to a breaker, then a short run to a bus bar attached to a heavier cable headed to their battery bank.
One of the reasons I like to suggest Morningstar for RV's is they don't use fans for cooling.
- Assorted other systems, pieces and to many panels in the closet to not do more projects.