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How To: run window air conditioner on solar - Printable Version

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How To: run window air conditioner on solar - urbanhermit70 - 02-28-2018

How does a person run  5000 -8000 BTU window air conditioner  on solar panel, solar generator,  or  portable gas generator? I keep hearing  this can be done.


Question:

 1.How many  watts  for solar panel ,solar generator  and portable gas generator watts?


RE: How To: run window air conditioner on solar - jimindenver - 02-28-2018

Realize that the Air conditioner itself plays into this equation. My high efficiency 5000 BTU A/C will run off of 750 watts of solar mounted flat during peak times and hold the battery voltage. My Sportsman 800 watt inverter generator will run it too but I haven't tried it at high altitude.


RE: How To: run window air conditioner on solar - Trebor English - 02-28-2018

There are two parts.  Daytime, hottest part of the day, you don't need to store the electricity to run the air conditioner in a battery.  At other times you need a battery to store the energy plus enough solar to charge the battery.  If you are in a desert location the temperature drops a lot when the sun is down.  If you are in central Florida the air conditioner uses a huge portion of the electricity condensing the moisture out of the air day amd night.  

There are many variables.  However much solar and battery you have there will be times when it is not enough.  Then a 1000 watt inverter generator will run the air conditioner.  The trade off is generator run time versus solar and battery size.  

The math is not that complicated, just expensive.  A Haier from Walmart takes about 500 watts.  A 2000 watt inverter will take about 50 amps of 12 volt DC to power that.  The duty cycle depends on outdoor temperature and humidity as well as insulation and the size of the space you want to cool.  It could be that 100% running doesn't get it to the 68 ° F that you want.  It could be that you are good with 80 ° and low humidity and a duty cycle of 50% is enough.  If you have a lead acid battery with a 20 hour rate of 50 amps that's 1000 amp hours used, 2000 amp hour capacity at 50% state of charge.  

If the 5000 BTU per hour air conditioner works at noon it will be much less than 100% duty cycle at midnight.  If your battery only has to provide 50 amps 50% of the time that cuts the size in half.  The peak solar time electricity doesn't get stored in the battery and that coincides with the peak heat time.

Solar panels to recharge what you use at this rate are large.  The first 500 watts produced go to the air conditioner directly.  

Ballpark, 800 to 1000 amp hours of battery and 1500 watts of solar would be a starting point.  Where you are and what tempetature and humidity you want can require double or half that.  If you want excess capacity to minimize generator use you can double.  If you don't mind a little generator every day you can cut the capacity required.  Cool dry nights can drastically reduce battery size.

Since there are so many variables that have such a huge difference it would be good to find someone who actually does this where you plan to be.  Check posts by BradKW to see what he has tried in Key West.  Search for posts by jimindenver if you are more likely to be at much higher elevation than sea level.


RE: How To: run window air conditioner on solar - jimindenver - 02-28-2018

To this I will add that a 5000 BTU A/C struggles quickly with humidity meaning the area it can cool is drastically reduced quickly.


RE: How To: run window air conditioner on solar - sushidog - 02-28-2018

I have a 1,200/1,500 watt generator that will run my 5,000 btu ac, even at altitude. A Yamaha EF2000IS or Honda EU2000I will burn about 0.2 gallons/hr at that load. Occasional use of a generator will save you from oversizing your battery bank/solar panel system for rainy/overcast times when solar isn't as productive. Also switching to a high efficiency mini-split rather than a window ac will save on the size of your solar system too.

https://www.amazon.com/Seer-Fujitsu-Single-Split-System/dp/B007TY294K Yes, it's $1,500 but will easily save you $1,500 in the size of the solar/battery system needed to run it, plus you can cool with it in the winter too. It's 9,000 btus but will draw less power to start and run than any 5,000 btu window ac.

They make a 33 SEER heat pump too but you will need a 220v inverter to run it. https://www.ebay.com/itm/9-000-Btu-33-Seer-Fujitsu-Single-Zone-Ductless-Mini-Split-Heat-Pump-System-/272757202744?rmvSB=true
You would need this to run it off a 12v battery bank. https://www.amazon.com/WEIKIN-power-inverter-1000W-converter/dp/B06XSMNVVX/ref=pd_day0_23_5?_encoding=UTF8&pd_rd_i=B06XSMNVVX&pd_rd_r=M0TWMP1FA0CVKQ9VAB95&pd_rd_w=5c2f9&pd_rd_wg=jy0i0&psc=1&refRID=M0TWMP1FA0CVKQ9VAB95


How To: run window air conditioner on solar - John61CT - 02-28-2018

I'm surprised no one's marketed a combination "hybrid energy aircon APU" unit, that drives a high-capacity aircon compressor directly off a little gas engine, and also concurrently charges your battery bank.

The latter's amps output could be varied as the compressor's load changes, a tiny efficient inverter could handle the aircon's electronics if they require mains power, and combined with a LFP bank, overall loads could be kept within a pretty narrow range optimizing the engine efficiency.

With a second DC motor, the gas engine can be automatically shut down once the bank is full, and aircon runs off the bank.

Solar inputs could be integrated too.

And now I've answered my own question, man would that setup be pricey, and even with marine/RV/off-grid homes combined, very limited worldwide markets.

Shouldn't be *that* difficult to cobble it together DIY though.

Personally I've never valued aircon that much, but refrigeration and watermaking would substitute.


RE: How To: run window air conditioner on solar - jonyjoe303 - 02-28-2018

at the hurriedyear.com website you can see the actual parts needed to run an ac in a van. He has a 780 ah battery bank (agm batteries) , thats almost 500 pounds of batteries. To me all that weight is a deal breaker on attempting it, unless you had lifepo4 then we talking it might be practical.  
With lifepo4 you would only need 400 ah, about 30 pounds per 100ah its only 120 pounds of batteries, still heavy but not a 1/4 ton heavy.


RE: How To: run window air conditioner on solar - frater secessus - 02-28-2018

(02-28-2018, 09:31 AM)urbanhermit70 Wrote:  Question:

 1.How many  watts  for solar panel ,solar generator  and portable gas generator watts?

I don't understand the question.


RE: How To: run window air conditioner on solar - jimindenver - 02-28-2018

You might say Jimindenver where it is dry as I never needed it in the monsoon while I was at altitude last summer. I did however run it daily in Yuma and Ehrenberg last year.


RE: How To: run window air conditioner on solar - Itripper - 03-01-2018

(02-28-2018, 08:43 PM)jonyjoe303 Wrote:  at the hurriedyear.com website you can see the actual parts needed to run an ac in a van. He has a 780 ah battery bank (agm batteries) , thats almost 500 pounds of batteries. To me all that weight is a deal breaker on attempting it, unless you had lifepo4 then we talking it might be practical.  
With lifepo4 you would only need 400 ah, about 30 pounds per 100ah its only 120 pounds of batteries, still heavy but not a 1/4 ton heavy.

You just need enough solar and the battery banks are mostly irrelevant. Ideally no battery power is being used. You just need to be near the 800 watt point in solar (at least but more like 1000watt) for lowest power draw 5000 btu acs.
No battery bank can run an ac for long on its own. A big enough solar system will run it as long as the sun is shining, say 9am to 4pm if the panels are tiltable, maybe 10am-3pm laying flat.