Use a single 60cell panel for a 24volt system prismatic cells

[Btsunrader]

So' I saw on youtube a professional installer say that a single 60cell panel will only charge 20 volts and is not recommended for a 24 volt system. Is this correct... I only have room for one large panel on my RV. all my components I have are for a 24 volt system using 100ah prismatic cells. Thank you​

 

[Rider]

You always want the panel voltage to be higher than the battery voltage, or little, if any, charge will occur. So rather than one large panel, get two smaller 24V panels and tie them in series.

 

[Btsunrader]

Here is what I don't understand the Voltage OCV of the renogy 300 watt 60 cell is 39.42 and is sold as a 24 volt panel.. Is this wrong?

 

[Craig]

Yes it should be fine. I think there are different voltages with other 60 cell panels. I have never really looked in to it but its easily possible to have 24 volt 60 cell panels and 12 volt 60 cell panels.

 

[Rider]

Not wrong. You need the VOC for sizing, but the nominal voltage is much less. My 270W Renogy is list as 24V but has a VOC of 38.1. When it's loaded, the panel voltage may drop to 22-27VDC.

Maximum Power: 270W	Maximum System Voltage: 1000 VDC (UL)
Optimum Operating Voltage (Vmp): 31.40V	Open-Circuit Voltage (Voc): 38.60V
Optimum Operating Current (Imp): 8.60A	Short-Circuit Current (Isc): 9.03A

 

[Btsunrader]

Ok so lets say then that I go with a 12 volt 60cell panel say 300watt and a smaller say 40watt 12volt panel , will that work, I think I could get a small one up their... Thanks for the help really appreciate

 

[Rider]

There are a couple of FAQs here that will better explain in detail than a few short sentences here...

Frequently Asked Questions

Links to commonly asked questions with long explanations: Beginner Video Playlist How much power does my device consume? Energy Audit How much Solar Energy should I expect where I live? What does it mean to have solar panels in parallel and series? How to figure out how much Solar and inverter...

diysolarforum.com

 

[Btsunrader]

Ok so after looking at Frequently AQ, It looks like I will just have to do a 12 volt 200ah Prismatic cell battery since I have such limited space for a panel.. Again Thank you for the help

 

[SolarRat]

There is no such thing anymore as a 12 or 24v panel (well there shouldn't be anyway). If your MPPT charge controller can convert XX volts (the panel's voltage) to your XX battery (12, 24, 48, 96) that is all you need to know.

If someone is marketing a solar panel as 12 or 24v these days find another supplier.

If you can fit, and find, a 72 cell panel, that will be higher voltage. They are cheap and on the "outs" because of new regs on total system voltages on residential homes...which is not at all pertinent to single off grid applications.

But a ~40v panel will charge a 24v bank just fine with an MPPT CC...it just won't be efficient on a cheap PWM (who cares, don't use one).