24 volt off grid

[txsjedi]

Have a question, I have 4 165w panels, 22.46v. If I set up a 24v array (2 each at 12v to get 24v from 4) how do I determine voltage for the right mppt charger?

 

[txsjedi]

Oh yea, the bank will be just 12v

 

[upnorthandpersonal]

You need to look at the maximum open circuit voltage your panels can deliver and compare that to the maximum your MPPT can handle. So if the 22.46V is that one, you have an array with an Voc of 44.92V when you put two strings (series 2 panels) in parallel - your MPPT needs to be able to handle that, plus some safety margin.

Edit: since your battery is 12V, this is a 12V system, not 24V.

 

[txsjedi]

You need to look at the maximum open circuit voltage your panels can deliver and compare that to the maximum your MPPT can handle. So if the 22.46V is that one, you have an array with an Voc of 44.92V when you put two strings (series 2 panels) in parallel - your MPPT needs to be able to handle that, plus some safety margin.

Edit: since your battery is 12V, this is a 12V system, not 24V.

Thanks, I was gonna do 24v array with a 12 bank. I read somewhere that it can be done. Was.going to do 4 200ah battery bank since I already have a 12v 2000w inverter, unless I read wrong.

 

[upnorthandpersonal]

Yes, you can even do a 150V array with a 12V battery. The MPPT is responsible for converting the solar side to the correct battery. You only have to make sure that your MPPT can handle the max. open circuit voltage of your array and the maximum short circuit current of your array. Based on that you make the decision.

 

[txsjedi]

Yes, you can even do a 150V array with a 12V battery. The MPPT is responsible for converting the solar side to the correct battery. You only have to make sure that your MPPT can handle the max. open circuit voltage of your array and the maximum short circuit current of your array. Based on that you make the decision.

Great, thanks. Now I understand. Still learning though

 

[tictag]

@txsjedi, this is a very common cause of confusion. Consumer retail marketing advertise solar panels as "12V" and "24V" but this is just to simplify things for the masses. A panel marketed as "12V" does NOT produce 12V, in fact they tend to produce 21.6Voc, which in turn is (usually) produced by connecting 36 individual 0.6V PV cells together in series.

The term "12V" (or "24V" or "48V") is used to combine compatible products together and is actually the 'nominal system voltage'. For example, a "12V" (nominal) battery can vary from 10V to 14.4V, a "12V" (nominal) PV panel can vary from 21.6Voc to around 19Vmp in operation and below depending on solar irradiance.

@upnorthandpersonal answered your main question regarding SCC selection.

Voc: PV Voltage Open Circuit
Vmp: PV Voltage Maximum Power

 

[txsjedi]

What's your suggestion on an mppt charge controller for less or right about $100?

 

[Supervstech]

With 22voc and 12v, unless you need thin wire, an inexpensive pwm charge controller works fine for 12v systems.
make sure the panels you use canbe placed in series configuration.

 

[tictag]

Personally, I tend to plum for Victron Energy products. You can pick up one of their 75|X BlueSolar range for less than $100 on Amazon. Bulletproof in my opinion. Other people on here also recommend EPSolar solar products, such as the Tracer range. I don't have any personal experience on these.

 

[Dzl]

This is a great Explainer Article from Victron on sizing/matching your controller and your solar array. All the info you need can be found there.

 

[txsjedi]

Has anyone that owns a epever charger have over heat problems?