Solar Air Conditioning

[SCOTTEDAVIS]

Considering a "marine AC" unit is over $2k this might make sunny days a bit nicer on-board.

Thoughts?? Comments



Hybrid Air H-11 is priced at a level that makes it affordable for virtually every one. The MSRP cost of the Hybrid-Air, the necessary solar panels and a roof mount for the panels is about $3,450.


Solar Air Conditioning Hybrid-Air Mini Split Heat Pump H-11

 

[Skinny]

I think that is nothing special, just a variable speed compressor mini split with a solar system wired to it. You could probably build that cheaper. I like the idea but you more than likely already have half the system on your boat if you are running a decent sized solar setup.

The big question is anyone running 220v in their boat? That mini split won't touch 120v so you may need to have some type of transformer.

 

[SCOTTEDAVIS]

Skinny, If they are running it stright off the panals then no transformer needed, they most likely are running 24 volt panals but that is a better way to go with a MPPT controller,it is more efficient and will allow 24volt to charge 12 volt batts.


From the site....

"During the day, the solar air conditioner receives DC power directly from solar panels without needing an inverter or controller. The DC solar power directly replaces the equivalent amount of AC power from the grid and can cut daytime energy costs by 80 to 90 percent!"

I wonder how it would deal with a cloud passing by?

The off-grid folks are mostly all 24 volt to a battery bank (or higher), as the cells are cheaper per Amp and with the MPPT controllers the level of efficiently is over 30% better then the old systems.

For warm climates having AC running for free (no noise maker) during the heat of the day would be nice. It may only be cooling one area in the boat but that would still be heaven.

The tropics would benefit the most but they have the most direct sun so it makes sense.

 

[cardude01]

I wonder if a regular marine AC would run off a solar setup, or do the marine units draw too many amps?

 

[Skinny]

I wonder if the guts inside the mini split are all DC based and simply taking a standard AC feed at night.

 

[cardude01]

Here's a 12v marine AC unit. 6000 btu and draws 18 amps. Would that run off a boat sized solar array?

http://www.cruisencomfortusa.com/mes-6000-se/

 

[BlueYonder]

The 18 amp spec is at the lowest power setting (only one of three compressors running). I doubt it is producing 6000 btu at that setting. It looks like it draws 40amps (plus whatever the water pump draws) at 12v dc at the high setting producing 6000btu.

 

[Heron]

Here's a 12v marine AC unit. 6000 btu and draws 18 amps. Would that run off a boat sized solar array?

MES 6000 | 12 Volt Marine Air Conditioner | Cruise N Comfort

Only a HUGE one! There is no free (energy) lunch...

 

[SCOTTEDAVIS]

Interesting, the price quoted as the MSRP would seem too low to include a LOT of solar panels, but it is running on 220 so that would lower the amp requirement.

Most 120 watt 24 volt panels are not too large to fit a few on a boat. The question would be how many are in the kit and what is the required real-estate.

 

[DavidM]

The 18 amp spec is at the lowest power setting (only one of three compressors running). I doubt it is producing 6000 btu at that setting. It looks like it draws 40amps (plus whatever the water pump draws) at 12v dc at the high setting producing 6000btu.

That gives it an EER of 6000/40+*12= 12.5 or less. Not so hot ;-).

David

 

[HopCar]

It looks interesting for home use but I think you'd need too many square feet of panels for use on a boat. You would still need to run a generator at night. I suspect you could buy a marine AC and a Honda to run it for about the same price.

 

[Johnm]

Interesting, the price quoted as the MSRP would seem too low to include a LOT of solar panels, but it is running on 220 so that would lower the amp requirement.

Most 120 watt 24 volt panels are not too large to fit a few on a boat. The question would be how many are in the kit and what is the required real-estate.

Scott, the 220volt will lower the amp draw but not the wattage, my rough calculations are,
6000BTUs / 3.412 = 1758 cooling watts, you will get around 3 watts of cooling for 1 watt of power in an A/C system so 586watts of power required. 120 watts per solar panel - 5 panels required .

 

[SCOTTEDAVIS]

Scott, the 220volt will lower the amp draw but not the wattage, my rough calculations are,
6000BTUs / 3.412 = 1758 cooling watts, you will get around 3 watts of cooling for 1 watt of power in an A/C system so 586watts of power required. 120 watts per solar panel - 5 panels required .

Thanks John, good information. Given the area to mount the panals it seems very do able. The panals would of course be also used to charge/power the house systems when not running the AC.

I love the idea of having air conditioning from solar power.

This type of technology will be the future as it matures. The last 5 years have seen lower cost and improvements in efficiency, the next 10 years will be exciting.

 

[Ski in NC]

Using DC power from solar panels for air con is not very efficient. There is a better way, at least from a thermodynamic perspective, that uses solar heat to drive the refrigeration cycle. Most common are ammonia or lithium bromide absorption cycles. The heat added by solar in a way replaces the energy input normally put into a compressor.

The problem is these systems are complex, need active control elements, can use very high or very low pressures, and in the case of ammonia, that's a nasty thing to use as a process fluid.

I sure wish we could come up with a simple refrigeration system that used minimal pumping power and could make use of heat either from solar or from a waste heat source.

Talk about a game changer.

 

[healhustler]

I love the idea of having air conditioning from solar power.

Double ditto! Our plan includes replacing our two current Kyrocera panels with a new system of about 1400 watts of panels on our pilothouse roof. Every year we delay the system possibilities increase. Looks like next winter to do the install now. I can hardly wait to see what becomes available by then!

 

[Lost Horizons]

Why marine engines don't have air con compressors like those in cars? At least for pilot house service?

 

[Ski in NC]

Why marine engines don't have air con compressors like those in cars? At least for pilot house service?

That's been done, and nothing more than basic engineering required. But in my case, I find when main engine is running I almost never run the the AC. Just open up the pilot house and breeze is enough. AC is GOD when sitting still or going to sleep.

 

[Johnm]

Thanks John, good information. Given the area to mount the panals it seems very do able. The panals would of course be also used to charge/power the house systems when not running the AC.



I love the idea of having air conditioning from solar power.



This type of technology will be the future as it matures. The last 5 years have seen lower cost and improvements in efficiency, the next 10 years will be exciting.

Yep, agree totally.
By the way ,You would need a good battery bank to start the compressors ( you probably already know that)
I will be at China Refrigeration Expo next week, lots of new technology there from all over the planet, I will let you know if I find anything of interest.

 

[long-cours.62]

Solar fridge

Using DC power from solar panels for air con is not very efficient. There is a better way, at least from a thermodynamic perspective, that uses solar heat to drive the refrigeration cycle. Most common are ammonia or lithium bromide absorption cycles. The heat added by solar in a way replaces the energy input normally put into a compressor.

The problem is these systems are complex, need active control elements, can use very high or very low pressures, and in the case of ammonia, that's a nasty thing to use as a process fluid.

I sure wish we could come up with a simple refrigeration system that used minimal pumping power and could make use of heat either from solar or from a waste heat source.

Talk about a game changer.

This (small) company doing this type of fridge , powerfull and solar , sale some to Arabian country .

COMESSE SOUDURE - Chaudronnerie dans les Vosges - Savoir-faire -

 

[timjet]

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.

 

[Lost Horizons]

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.

 

[DavidM]

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

 

[healhustler]

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.

 

[Lost Horizons]

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.)

 

[Skinny]

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