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Old 04-05-2015, 10:48 AM   #21
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Even with the entire surface of a boat covered with solar panels, they will not be sufficient to power an air conditioner without an additional source of power. The reason is that one square meter of solar panels can produce up to 1kW*hour electricity per day in ideal conditions, and a full boat air conditioner for a 40-45 foot trawler needs at least 50 kW*hours of power a day.
The benefit of a small efficient AC is to cool a cabin at night without running a generator. It can be done with an inverter an a conventional A/C air conditioner, so I don't see a need for the subject D/C device.
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Old 04-05-2015, 03:38 PM   #22
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Conventional marine A/C systems like Cruiseaire are not very efficient. The EER is about 9. SEER may be higher, perhaps 12. But modern inverter driven minisplit A/C systems achieve a SEER of 18 or better.

The DC system that started this thread seems to be about twice as efficient as a Cruiseaire and it might be even better at night when load factors drop. A small 3-5,000 BTU/hr system just to keep one cabin cool at night might work with that efficiency. It would need a big battery bank, probably 400 AH and a big solar array, about 600 watts to make it work.

David
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Old 04-05-2015, 05:14 PM   #23
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Quote:
Originally Posted by timjet View Post
Is solar really a practical solution to power an air cond unit? In our experience night is when its needed most. Perhaps solor will eventuality be the holy grail of energy production, but battery technology and the panels themselves have a ways to go before they will repalce the trustworthy but thirsty genny.
Well said.
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Old 04-05-2015, 06:05 PM   #24
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Originally Posted by djmarchand View Post
Lost Horizons:

Conventional marine A/C systems like Cruiseaire are not very efficient. The EER is about 9. SEER may be higher, perhaps 12. But modern inverter driven minisplit A/C systems achieve a SEER of 18 or better.

The DC system that started this thread seems to be about twice as efficient as a Cruiseaire and it might be even better at night when load factors drop. A small 3-5,000 BTU/hr system just to keep one cabin cool at night might work with that efficiency. It would need a big battery bank, probably 400 AH and a big solar array, about 600 watts to make it work.

David
Unfortunately, once you decide to use an AC at anchor, a generator is a requirement. You can offset daily running time of a 6 kWt generator by about 30 minutes by having a 600 Wt solar panel array.
Without a generator and only for nighttime use of a smallest highly efficient AC unit, such as the subject one, plus other typical on board appliances, one would need about 2 kWt solar array and ideally about 20 kWt*h battery bank for efficient charging. (20 kWt*h = 17 group 31 batteries, by the way.)
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Old 04-05-2015, 06:17 PM   #25
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I think you should install a large concrete slab up in the V-berth and use solar to drop it's temperature during the day so you can sleep comfortable at night

I think the major power savings with these mini splits is the compressor unit itself. The old fashioned on/off cycling power hog should just die and go away. Variable speed/displacement is king these days. I'm sure new refrigerants are on the way as well to increase efficiency.

Just do what our military does and use a cooling vest to stay comfy. You could probably just pull sea water from a thru hull and circulate it around your body to stay cool. Climate control is nothing more than removing heat from your body unless you are really picky about breathing in humid air. A pump could run off a battery...although your personal life may be affected if you know what I mean Vern
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