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Open Roads Forum  >  Tech Issues

 > 12V heater run straight from solar panel

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DarkSkySeeker

Freestone, California

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Posted: 03/26/20 11:54am Link  |  Quote  |  Print  |  Notify Moderator

Is there a heater product that can run off the 12V that comes directly off my portable solar panel? This would have to be something that can handle unregulated power that might peak up during bright sun and drop very low when a cloud passes by.


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agesilaus

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Posted: 03/26/20 12:03pm Link  |  Quote  |  Print  |  Notify Moderator

Even small 120 VAC heaters are 1200 to 1500 watts, that's a lot more than most peoples solar can put out. Heating is energetically expensive as is cooling aka air conditioning. But here are what is offered on Amazon


Be careful some are deceptive, the one 'universal heater' for example uses hot water from the engine block and the 12V is to run the blower motor.


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Lwiddis

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Posted: 03/26/20 12:13pm Link  |  Quote  |  Print  |  Notify Moderator

Never encountered a heater that would run solely from solar.


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DarkSkySeeker

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Posted: 03/26/20 12:26pm Link  |  Quote  |  Print  |  Notify Moderator

agesilaus wrote:

Even small 120 VAC heaters are 1200 to 1500 watts...

Thanks. Yeah, I was imagining a big resistor with a heat sink around it that would run passively. Perhaps I will find that.

Ed_Gee

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Posted: 03/26/20 01:05pm Link  |  Quote  |  Print  |  Notify Moderator

Maybe something like this would work for you ....

12 Volt heat lamp


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agesilaus

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Posted: 03/26/20 01:05pm Link  |  Quote  |  Print  |  Notify Moderator

DarkSkySeeker wrote:

agesilaus wrote:

Even small 120 VAC heaters are 1200 to 1500 watts...

Thanks. Yeah, I was imagining a big resistor with a heat sink around it that would run passively. Perhaps I will find that.


That's what these electric heaters are. Resistor: NiChrome wire coil
Heat Sink: The surrounding air

The problem is that it takes many Joules to heat up that air and get ahead of heat losses thru the walls, air leaks and such. You can't sneak around the Laws of Thermodynamics.

DrewE

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Posted: 03/26/20 01:29pm Link  |  Quote  |  Print  |  Notify Moderator

A big resistor that can dissipate a lot of power at 12V, sufficient to be a useful heater, is also a low-valued resistor, on the order of one ohm (approximately 150 watts). Making your own with resistance wire would probably be easier and less expensive than finding and affording a commercially produced resistor, marketed as such. Having a few coils wired in parallel is probably a good idea, too.

I'd think, for heating with solar power, that a solar water heater (as in a black pipe in a reflective trough or something similar) and a radiator of some sort would be more efficient and effective overall. The cost would probably be lower, too.





DarkSkySeeker

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Posted: 03/26/20 01:40pm Link  |  Quote  |  Print  |  Notify Moderator

DrewE wrote:

A big resistor that can dissipate a lot of power at 12V, sufficient to be a useful heater, is also a low-valued resistor, on the order of one ohm (approximately 150 watts). Making your own with resistance wire would probably be easier and less expensive than finding and affording a commercially produced resistor, marketed as such. Having a few coils wired in parallel is probably a good idea, too.

I'd think, for heating with solar power, that a solar water heater (as in a black pipe in a reflective trough or something similar) and a radiator of some sort would be more efficient and effective overall. The cost would probably be lower, too.

Agreed. My basic motivations are like this: I have these solar panels and what if I used them to generate ~500W continuously? And to avoid the complexity of a water heater based system, I wanted to be able to attach the 1 ohm resister(s) to create passive and unregulated heat.

DarkSkySeeker

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Posted: 03/26/20 01:55pm Link  |  Quote  |  Print  |  Notify Moderator

What if I bought 5 of these, wired them in parallel, and mounted them on a board?

PRODUCT LINK

Flute Man

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Posted: 03/26/20 02:34pm Link  |  Quote  |  Print  |  Notify Moderator

I have a 12 V 300 W heater in my rally compartment. It draws 25 A so figure yours accordingly.
Electric heaters have a very simple formula.
Watts Divided by volts equals amps.


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