24volt solar panel on 12volt system?
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wrcsixeight
Adventurer
24 volt panels are desirable because the wiring from it to the charge controller can be thinner. I'm pretty sure you need a MPPT charge controller(versus a PWM) which acts like a dc to dc converter. It basically changes the extra volts into amps at the correct voltage to correctly charge the batteries.
The bad news is MPPT controllers are expensive, and the less expensive models are not rated for 24 nominally rated volt panels. The good news is MPPT charge controllers can produce up to 30 % more power in cool weather with depleted batteries versus PWM.
If the 24v panel is small, you could hook it right upto the battery, but the battery voltage will limit the output of the panel greatly, and when the battery does eventually reach full charge, it can then go way beyond full charge and boil out the electrolyte, and the voltage can rise so high as to damage anything hooked to the battery, so it is to be avoided unless monitored very closely and the panel removed before the battery gets above 15 volts.
The bad news is MPPT controllers are expensive, and the less expensive models are not rated for 24 nominally rated volt panels. The good news is MPPT charge controllers can produce up to 30 % more power in cool weather with depleted batteries versus PWM.
If the 24v panel is small, you could hook it right upto the battery, but the battery voltage will limit the output of the panel greatly, and when the battery does eventually reach full charge, it can then go way beyond full charge and boil out the electrolyte, and the voltage can rise so high as to damage anything hooked to the battery, so it is to be avoided unless monitored very closely and the panel removed before the battery gets above 15 volts.
VicHanson
Adventurer
You don't need the MPPT charge controller, it just makes better use of the higher voltage under the conditions mentioned above. From what I have read, much of the time they don't help that much so I decided to use a regular one. The price difference is substantial.
Morningstar TS60 Charge Controller Morningstar's TriStar™ is a three-function controller that provides reliable solar battery charging, load control or diversion regulation. $189.72
Morningstar TS-MPPT-60 Charge Controller Morningstar’s TriStar MPPT solar controller with TrakStar Technology™ is an advanced maximum power point tracking (MPPT) battery charger for off-grid photovoltaic (PV) systems up to 3kW. $502.89
For your one panel you wouldn't need a 60 amp controller - I'm using 3 panels at 210 watts each, 37 amps total.
Vic
Morningstar TS60 Charge Controller Morningstar's TriStar™ is a three-function controller that provides reliable solar battery charging, load control or diversion regulation. $189.72
Morningstar TS-MPPT-60 Charge Controller Morningstar’s TriStar MPPT solar controller with TrakStar Technology™ is an advanced maximum power point tracking (MPPT) battery charger for off-grid photovoltaic (PV) systems up to 3kW. $502.89
For your one panel you wouldn't need a 60 amp controller - I'm using 3 panels at 210 watts each, 37 amps total.
Vic
MPPT can actually make a substantial difference.
And they can be found for not so much:
[ame="http://www.amazon.com/SolarTorrent-STCMPPT10-Solar-Regulator-MPPT/dp/B0030H5ABY"]Amazon.com: Solar Regulator, 10A, MPPT: Patio, Lawn & Garden[/ame]
Oh and more variety and much cheaper on Ebay...just search "mppt".
...so, really no reason to NOT buy an MPPT charge controller.
And they can be found for not so much:
[ame="http://www.amazon.com/SolarTorrent-STCMPPT10-Solar-Regulator-MPPT/dp/B0030H5ABY"]Amazon.com: Solar Regulator, 10A, MPPT: Patio, Lawn & Garden[/ame]
Oh and more variety and much cheaper on Ebay...just search "mppt".
...so, really no reason to NOT buy an MPPT charge controller.
dzzz
™
I expect it depends on the quality of the implementation, and that the benefits are exaggerated. Not that I would buy an older style for a good size array.
I was thinking that a $50 controller would be about right for a single free panel. But the $100 off brand MPPT may be as good as he can do since he needs 24 to 12v.
I'm shopping for a 30A charge controller. I wish outback made a smaller version of their units.