easy, DIY solar powered AC for small room??

Was "the battery" your car's battery, or some other battery?

If it was the car battery or some other 12V battery that was big enough to provide the current that the fan needs, and if you connected the fan in the correct direction, then it should have worked.

But your post is really very sparse on detail, so it's hard to say.

--
www.wescottdesign.com

0

by

e

if

st

Using solar panels to charge a battery and then having an inverter to chang e the DC power to AC to run a air conditioner is not very efficient.

You could use solar panels and an inverter to pump power into the power gri d and then run the air conditioner off the power grid. This would at least avoid the cost of batteries. Essentially using the power grid as a batter y. It would avoid a lot of problems. Still probably not actually cost eff ective.

The most cost effective thing to do is to insulate the room better and use a smaller AC unit. Another thought is to get a water bed. If the room is at 85 degrees , the room seems hot. But a water bed with water at 85 degre es will feel cold.

Dan

In part this is not cost effective because of the huge overhead costs involved in sharing power this way. I don't know the cost of maintaining your own batteries, but selling power to the utilities and then buying it back later has a lot of overhead. I think you get about

50% return, at least here where they are mandated to buy your power "at cost". But it is the cost of the power, not the cost of distribution and transmission and the other "fluff".

It has been demonstrated many times that the best cost savings come from conservation.

Not sure what a waterbed will do for you though. They feel cold when you lie on one without an insulating layer between you and the bed. They won't help to cool you though. If you remove the insulation they will feel *too* cold like lying on marble.

--

Rick

Have you seen any 12 V air conditioners in your area e.g. for mobile homes ?

Why not connect such unit directly to the panel(s).

Since the power is needed in the afternoon and evening, aim the panel(s) towards southwest (assuming Northern hemisphere) and tilt them so that they are perpendicular to the sun rays in the afternoon of the hottest month. This way, you get the largest power just when you need it.

A small (a few Ah) battery may be needed to handle the motor startup peak. The poles of the battery is a convenient place to put some undervoltage protection to prevent the AC to start before noon and during cloudy days.

For hot cloudy days, running the AC from the grid would be the cheapest solution.

Actually they will help to cool you. With the water bed at 85 degrees and your body temperature at 98 degrees , the heat will flow from you to the wa ter bed. The trick is enough insulation so you do not feel cold, but not s o much that there is no cooling. Pretty much the same as blankets. Enough to feel warm, but not so many blankets that you sweat.

Dan

"Help" in the most minimal way. Besides, who wants to spend the day in bed? Oh, I do!

--

Rick

and your body temperature at 98 degrees , the heat will flow from you to th e water bed. The trick is enough insulation so you do not feel cold, but n ot so much that there is no cooling. Pretty much the same as blankets. En ough to feel warm, but not so many blankets that you sweat.

The orginal post was about running the air conditioner so in would be cool for sleeping.

Dan

True, but I had an unheated water bed once and it was nearly impossible to provide enough insulation that it didn't suck all the heat out of your body. Trying to get just enough insulation to make it cool and still feel good would be nearly impossible. Not only do you have a problem with getting the right balance, which varies depending on your body state, insulation depends on air space which varies depending on how hard you squeeze the insulation resulting in cold spots around your bony parts.

I was around 20 at the time and that durn bed made me feel like I had arthritis no matter what I did.

--

Rick

You are probably right. I have to admit that I have never had a water bed.

Maybe you could have a heater and adjust the temperature and insulation so that it was comfortable to sleep even when the room is warm.

Dan

I saw a solar air conditioner at an energy fair a long time ago. They had a polished dish about 6 feet in diameter on an equatorial tracking mount. At the focus, there was a boiler. The working fluid was apparently some variant of Freon with lower vapor pressure, possibly Freon 11. (You can't get that now.) This ran a pelton turbine, through a gearbox and turned an automobile air conditioning compressor. That cooled the space with adapted car A/C components. There needed to be a feed pump for the boiler, I didn't see how they did that part.

A good thermal solar absorber with concentrator will harvest a LOT more energy from the sun than typical consumer-grade solar panels. Even with a mediocre heat engine, it will far outdo photovoltaic.

A Stirling engine ought to be able to do even better, unless you go to steam at insane temperatures, with multiple regeneration stages.

Jon

0

by

e

if

st

THe biggest stumbling block is the very poor power conversion efficiency of solar power panels -- at most 25% from a very high quality manufacturer. The charge controller/conce ntrator is cheap. Despite what some other people claim, a simple shunt type charge controller does the job admirably, without the added expensive of a switched mode device. If you are running just the AC, the inverter does not have to be a pure sine wave type, and that would reduce costs further.

olved in sharing power this way. I don't know the cost of maintaining your own batteries, but selling power to the utilities and then buying it back later has a lot of overhead. I think you get about 50% return, at least he re where they are mandated to buy your power "at cost". But it is the cost of the power, not the cost of distribution and transmission and the other "fluff".

That's only true if you are selling excess power back to the grill. Namely , your net monthly bill is negative. But if you are just reducing the usag e, especially top tiers, which are very expensive. It might be cost effect ive.