How To: run window air conditioner on solar

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urbanhermit70

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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?
 

jimindenver

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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.
 

Trebor English

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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.
 

jimindenver

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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.
 

sushidog

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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-...lit-Heat-Pump-System-/272757202744?rmvSB=true
You would need this to run it off a 12v battery bank. https://www.amazon.com/WEIKIN-power...rd_wg=jy0i0&psc=1&refRID=M0TWMP1FA0CVKQ9VAB95
 

John61CT

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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.
 

jonyjoe303

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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.
 

jimindenver

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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.
 

tripper

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jonyjoe303 said:
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.
 

John61CT

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A large LFP bank and a charger+genny that puts out say 4 times more than the aircon consumes, could run 24*7 with the genny running say two hours out of every eight.

Maybe $8k worth of gear though, plus fuel costs, lots of space and weight.

With enough solar you might eliminate a third of the genny runtime, say $2k added costs.
 

tripper

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Riverman said:
If you have enough $$$$ to experiment (thousands) you may get a setup that would work, when the sun shines.

My 2000--watt inverter generator simply works....  all for $375.

https://www.supergenproducts.com/catalog/p-100047/73536r-17002000w-refurbished-inverter

You can build a large enough solar/battery/controller/inverter setup that will work for $2200.  And then you have unlimited power for everything, not only the AC. Not an experiment, because I have it, run microwave, 12v fridge, normal coffee maker, 5k ac, ice maker, etc. Useful year round.
 

highdesertranger

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I don't understand this whole AC stuff. the last thing I want to do is sit inside a van/RV all day, I want to be outside doing something. I just go where it's not so hot. I would go crazy if I had to be cooped up all day. well crazier anyway. highdesertranger
 

jimindenver

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Like Itrpper my solar does so much more for me than run the A/C. I would love to discuss it but maybe in a thread about the differences of using solar vs a generator. This thread was intended to discuss the requirements of what it takes to run a A/C.
 

Motrukdriver

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highdesertranger said:
I don't understand this whole AC stuff.  the last thing I want to do is sit inside a van/RV all day,  I want to be outside doing something.  I just go where it's not so hot.  I would go crazy if I had to be cooped up all day.  well crazier anyway.  highdesertranger

My sentiments exactly.  When I get back out there I'll be on the move every 2 weeks or sooner if the weather becomes a big meanie.  I'm also gonna assemble a small swamp cooler in case I get stuck for a day or two in warmer than sleeping comfortable weather.  Just like in real estate sales... Location Location Location.
 

urbanhermit70

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frater secessus said:
I don't understand the question.


To run a 5000-8000 BTU window air conditioner ,how many watts Solar panel, solar generator and gas portable generator?  EXAMPLE: some people are using 1000 watt portable gas generator to run a 5000 BTU AC. Some people are using 950 watt solar panel to run an AC
 
 

frater secessus

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Riverman said:
If you have enough $$$$ to experiment (thousands) you may get a setup that would work, when the sun shines.

My 2000--watt inverter generator simply works....  all for $375.


We know;  we can hear it running.

This thread is called "How To:  run  window air conditioner on solar."
 

Technomad

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I think the answer is very clear, but has two steps:

1. Size your battery bank and inverter sufficient to run your Air Conditioner.

2. Adjust your lifestyle so that you are moving to higher elevations when it gets hot. Or if you can’t be mobile (living in someone’s driveway to take care of a sick friend) acquire enough supplementary power to back up the solar power when your bank runs out. Eg: your friend should provide you a 20A hookup while you’re there.

There’s absolutely nothing wrong with wanting to run an AC, sometimes circumstances mean you can’t relocate right away....


Sent from my iPhone using Tapatalk
 

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