24V Solar Panel, 12 V Battery

[felixx]

I may have a lead on some 24V Panels for free.
I run a 12V Battery

Is there a way to make this work simply?

Thanks for your replies..

[felixx]

I think an MPPT controller will do this

I hope to hear about the panels tomorrow.

It is all coming together for me

[Shadow Catcher]

I have a high voltage panel meant for a grid tie system and I have seen no load voltages in excess of 70V. Typically I see 36+V with the Morningstar MPPT controller even when shaded to some extent. I get usable current from sun up to sun down and in shade. So yes a great idea.

[jss06]

Yes but you need a mppt controller.

[MtnDon]

Yes but you need a mppt controller.

Not necessarily true. It may be best, but may not ne necessary.

If the panels are free then it does not really matter if powered from the PV is wasted. A PWM (non MPPT) charge controller could be used as long as it can handle the higher input violtage. Yes, there will be wasted PV power but if the panels are free that does not matter much. One potential issue from doing that could be that the PWM controller may run hotter than id better matched to the panels / batteries.

OTOH, if the panels are free then perhaps the higher price of the MPPT controller does not matter as much and you could take full advantage of all the power from the 24 volt panels.

[H.A.]

......

[MtnDon]

Different ways to look at things, that's all. If the budget one has is very low and it is of prime importance to keep the costs to a bare minimum, then free panels and a low cost PWM makes sense to me. Not saying I would do that because wasting that available pv power would bother me. But I do believe there are 2 sides to every coin.

[bdosborn]

Yes but you need a mppt controller.

Not necessarily true. It may be best, but may not ne necessary.

I'd be curious to see a PWM controller that is rated for an input voltage high enough to accommodate a 24V panel but still has a 12V output. I looked awhile ago and came up empty.

Bruce

[MtnDon]

Midnite Solar Brat.... 60 VDC max input, 30 amps charge, 12/24 volt battery... flooded, agm, gel
Bulk, absorb, float plus EQ
Weather proof IP55

info linky

buy here linky


I have one

[Shadow Catcher]

Bruce Steca makes a PWM controller that will handle a 47V.

[bdosborn]

Sigh, I haven't been looking at solar stuff lately. It looks like they've got some higher rated stuff out there now. I'd say it's a no brainer; I'd go with the PWM over MPPT. MPPT is just too expensive to justify the added efficiency on a small system.

Bruce

[Shadow Catcher]

Bruce where we are here in the Mid West there are almost always trees and they are most often deciduous. I seldom get full sun. I do not know how much the MPPT helps but the whole package works. I got the STECA controller to use with the Unisolar flexible 18' 135W panel.

[flboy]

If you have enough of the cells and do not mind wasting some of the potential.... a cheap way would be to just take some dark material and block the sun from half the cell (or an appropriate amount to get about +14VDC. On cloudy days or in partial sun, remove it. I'd use a PWM regulator in any case.. and buy one with good operating margins. Just a thought.

[bdosborn]

Hmm, sounds like shading to me. My panels will go to pathetic output with an amazingly small amount of shade on any part of the panel. I'd recommend testing the panel with a voltmeter to see if this method works before committing to it. Unisolar is an exception as I think they have isolation diodes between segments. Mine don't have that feature, they only have a night bypass diode.

Bruce

[felixx]

Since the panels will be free (I hope)
I will spend $ on an appropriate controller

I will update as I get more info