Need two X 24 volt 10 - 20 watt panel with blocking diodes.

Oops sorry, I was thinking bypass diodes.

The neat thing with choosing the converter route is you get to choose the panel from a selection of hundreds of different 17, 19, 21, 14, 28 volt models.

Thanks for the suggestion Mex. I'll give it some thought. I wanted the blocking diodes to prevent reverse current at night.

Thanks all.

It all depends on "the" interpretation of "blocking". Shading blocking or reverse current blocking.

John & Angela wrote:

smkettner wrote:
I would guess most do not have a blocking diode but rely on a controller.
Probably going to need to contact some manufacturers directly.
Only seen diodes listed if it is designed as part of a kit to maintain a battery.

Agreed. We found a 48 volt inexpensive controller that should work. Coupled with a couple of 24 volt 20 watt panels the whole thing will come in around 130 bucks.

Yes but the typical 3 blocking diodes/panel won't help with shadows since this seems to be your requirement. When a blocking diode disables a panel section you lose that voltage and you could easily get below the charging voltage for the 48V battery. Now if you can find adequate voltage panels with say one diode per cell then the diodes can be effective.

Orrrrrrrrrrrrrrrrrrrrrrrrr,

You can use ANY panel of around 30 watts, and a DC to DC converter like the 600 watt found on Amazon. 56.0 volts is nominal bulk charge limit on a 24 cell system which is 8 volts higher than 2.0 volt X 24 = 48. Split the difference, add 4 volts and 52 volts will be your float. Therefore you will be boosting from 12 volts minimum to 52. This is well within the design specifications of the booster.

I cannot imagine a high voltage panel array for as little money as the most economical 30 watt lower voltage panel you can find + a twenty eight dollar booster. The boosters are rugged. If you want it bulletproof play a 12 volt computer fan on the booster fins which would be wired directly to the panel.

This setup is no more difficult or complicated than setting up your idea of panels plus a controller. Strike that. This is a single panel affair I am suggesting - considerably less work. The booster positively disconnects the panel when there is no voltage on the booster input.

Remember 52, the number of cards in a deck.

Piece of cake...

smkettner wrote:
I would guess most do not have a blocking diode but rely on a controller.
Probably going to need to contact some manufacturers directly.
Only seen diodes listed if it is designed as part of a kit to maintain a battery.

Agreed. We found a 48 volt inexpensive controller that should work. Coupled with a couple of 24 volt 20 watt panels the whole thing will come in around 130 bucks.

I would guess most do not have a blocking diode but rely on a controller.
Probably going to need to contact some manufacturers directly.
Only seen diodes listed if it is designed as part of a kit to maintain a battery.

I've not seen them that small above 12v. Two 12v in series wouldn't do it either. It would take three panels in series and a PWM controller.