Solar Air Conditioner

Yep, it's a version of the old "swamp cooler". Downside if there's much humidity all bets are off, plus they pump a lot of water into the air, which is not always good.

westend wrote:
Good stuff guys. What I'd like to see is a small AC unit, even down to 2K or 3K BTU but with much less draw. If I could find an AC unit with lower draw, I'd increase my bank to 500AH and get more modules on the roof.

I'm kind of like Jim, in that I usually camp/boondock at places where the ambient isn't to bad. I also have my trailer insulated about as best as possible.

I would think a < 5K unit would keep the cabin temps in a range that would be very comfortable. I have an 8K BTU AC in my tent camper and at 85f with high humidity, it becomes a meat locker. I have to turn it off at night because the family freezes.

With the ultra-insulated, sealed cabin, less would be great.

Here's a small ac unit:
http://www.climaterightair.com/applications/outdoor-dog-house-air-conditioner-and-heater/climateright-2500-btu-mini-ac-heater.html
It has 2,500 BTUs of output, and draws 480 watts or 4.3 amps (7 amps at start-up) at 110v, so it is not very efficient compared to the last heat pump I posted which produces 12,000 BTUs from only 560 watts.

Good stuff guys. What I'd like to see is a small AC unit, even down to 2K or 3K BTU but with much less draw. If I could find an AC unit with lower draw, I'd increase my bank to 500AH and get more modules on the roof.

I'm kind of like Jim, in that I usually camp/boondock at places where the ambient isn't to bad. I also have my trailer insulated about as best as possible.

I would think a < 5K unit would keep the cabin temps in a range that would be very comfortable. I have an 8K BTU AC in my tent camper and at 85f with high humidity, it becomes a meat locker. I have to turn it off at night because the family freezes.

With the ultra-insulated, sealed cabin, less would be great.

Jimindenver, that is definitely a cheap way to go if you only need 5,000 BTUs of cooling. It's similar to the AC in my Aliner which I run with a 1,200/1,500 watt geny. However it only has an EER of 11.2, not bad as far as window ac's go, as many this size are only in the 9.5-10.5 EER range. The AC I linked to however has an EER of almost 21.5 meaning it will produce roughly twice the cooling power from same wattage draw. So if you truly only need 5,000 BTUs of cooling most of the time it will only be drawing around 250 watts with it's variable speed compressor and scalable power draw/output. Plus, being a native DC device you don't have any inverter loss, making it roughly 10% more efficient than converting from DC to AC power that a window unit AC would require. Remember that 3.9 amps is at 120v which will convert to a about 43 amps at 12v (assuming a 90% efficient inverter.) 720 watts of solar panels might keep up at peak sun, but just barely.

A better comparison is to an Arctic Breeze 12v truck AC. It draws 600 watts, making 8,000 BTUs, but like most ACs it must cycle (turn off and on)to reduce its cooling output. 8,000 BTUs should easily be enough to cool a single RV bedroom if you have decent insulation. My Aliner barely gets by with a 5,000 BTU AC, but it is tiny, (less than 100 sq. ft.) only slightly larger than an big RV bedroom, though it is well insulated. This unit draws 45 amps at 12 volts, but it will probably be running only 60% of the time, meaning that your average wattage draw would be about 30, making it much easier for your solar to "keep up" when not in peak sun. Still, 3-4 8-d batteries would give a much more comfortable buffer, and wouldn't be stressing your battery bank as much from the Peukert effect of such a high current draw from a single battery when the sun isn't cooperating.

http://www.arcticbreeze-truckac.com/content/arcticbreezeintro.html

Chip

JiminDenver wrote:
This is the you tube about the bucket evaporator cooler.

Click

A buddy of mine who owns an older VW Westfalia camper, made his own version of the cooler in this u-tube vid. However, he used a small styro cooler in place of the 5 gal bucket, which of course gives much greater insulating power. And he uses dry ice instead of regular ice. He found using dry ice, the ice lasted for a full 7 hour drive.

This is the you tube about the bucket evaporator cooler.

Click

I am not saying this will work for anyone else, may not even work for us. Who knows?
This Window shaker uses 3.9a/ 446w on high and we have 720w of solar tracking the sun. A 8-D will take the surge of start up and I am hoping the solar will run it and leave the battery in float. At peak the array can produce 50a/ 650w. Luckily at 10,000 ft when the sun hides behind a cloud, the temps drops quickly. So no sun means no air needed.

Now being a dry state like Colorado is, swamp coolers work great up to a certain degree/ humidity. There is a you tube of a bucket swamp cooler that probably would do well for us if we had a larger supply of water. I can produce the electricity to run the A/C, I can't make water.


Edit fixed the link.

I just saw a new development in solar ACs that are even more efficient, requiring even less battery power. Here's the link: http://www.geinnovations.net/Specifications.html

This new super high-efficiency heat pump (EER = 21.43) only requires 560 watts (11.5 amps) of 48v dc to produce 12,000 BTUs of cooling - about 60% of the previous high efficiency solar heat pump I linked to! Plus, like the previous system, the rotary compressor doesn't cycle on and off like a typical ac unit. It ramps up and down from 5,000 BTUs to 12,000 BTUs as required, so no high current start-ups are needed, saving even more power. Yes, a solar ac system will still be heavy, but 1,500 watts of solar should be sufficient to replenish your 8 - 6v GC-2 battery bank, not 2kw as was previously suggested with the other less efficient AC unit. As time passes and technology improves, the prospect of solar ACs gets more and more practical, extending one's boondocking season even longer, especially if you plan on only cooling a single bedroom at night, for a good night's sleep (when it's cooler outside anyway) and not the entire trailer, as you would during the day when there is plenty of solar power available. Let's say you start the night with 200 ah in your batteries (at 48 v) or 100 ah available and your AC averages only 6 amps draw (about 1/2 power, as things are cooling off), that means that you could run it for over 16 hrs. before you reach 50% battery capacity, leaving extra power available to run other things. Or you could cut your battery bank in half - say only 4 - 12v deep cycle batteries and still run your solar AC for a full 8 hrs before your batteries reach the 50% level. Let's say you have 4, Trojan T1275s (150 ah 12v batteries, leaving power to spare). Since you are normally outside most of the day and won't be using your AC then anyway, a full day of sun on those 1,500 watt panels and you should be good to go for another night of comfortable sleep (and an evening of a couple hrs. TV viewing, lighting and water pump use to boot). If it's a cloudy day, a back-up EU2000 Honda run for few hours or a supplemental wind generator should be enough to make up the difference and get that battery bank up to capacity again.

Chip

Barney

Thanks - I shall try this

Reed

reed cundiff wrote:
Snip...
I can send you photos of system via e-mail if you like since I have not figured out how to attach photos to this forum

Reed and Elaine

It is extremely easy now that we have a site dedicated to posting pictures on the forums. Take a look at this thread, which is stuck at the top of this forum for instructions. It is basically cut/paste.
Barney