Running a 5,000 watt AC with solar and batteries

[akrvbob]

One of the key factors we aren't factoring for is insulation. If you super insulate with 4 inches of Polyiso (almost R-30) you would have very little run time. More important, you would have very little night time usage. It's the overnights that kill solar powered AC.

If you can find an AC that draws 400 watts, put 945 watts on the roof (3 Kyocera 315 watt panels) and 8 golf carts, I think you've got it made.

However, with that much insulation you MUST run AC or it will be unbearably hot. It would never cool off at night. I'd carry a generator as back up.
Bob

 

[jimindenver]

Last year I used 720 watts in three panels, 3 20 amp MPPT controllers, 345 Ah of battery and a 3000w PSW inverter. This year I bought matching panels to mount, 750 watt, will replace the inverter battery with four 6v, over 400 Ah and am using a industrial 1250w inverter.

 

[SoulRaven]

One of the key factors we aren't factoring for is insulation. If you super insulate with 4 inches of Polyiso (almost R-30) you would have very little run time. More important, you would have very little night time usage. It's the overnights that kill solar powered AC.

If you can find an AC that draws 400 watts, put 945 watts on the roof (3 Kyocera 315 watt panels)  and 8 golf carts, I think you've got it made.

However, with that much insulation you MUST run AC or it will be unbearably hot. It would never cool off at night. I'd carry a generator as back up.
Bob

8 golf cart batteries? That certainly gives the generator the edge. It would be much easier to just use a generator and not have to put up with all the weight and maintenance of the system. I mean it is just to run an  5,000watt AC. Thanks Bob for your knowledge on this. 

 

[SoulRaven]

Go with the genny.No question.You can buy a nice honda genny for a thousand bucks.Or if you're cheap like me,get a HF 800watt for $90.

After reading the information on the responses I will have to agree about going with the gen.

 

[SoulRaven]

Last year I used 720 watts in three panels, 3 20 amp MPPT controllers, 345 Ah of battery and a 3000w PSW inverter.  This year I bought matching panels to mount, 750 watt, will replace the inverter battery with four 6v, over 400 Ah and am using a industrial 1250w inverter.

Thanks. This helps me get an idea of real life numbers of what it takes to produce enough solar to be useful.

 

[jimindenver]

Like I said I wouldn't have built it up just to run the AC, we do a lot with our solar.

 

[SoulRaven]

900 watts seems very high for a 5000 btu ac.Best I remember,mine pulls around 4 amps ac.

Is that just for the fan? I have seen 450 watts mentioned. Is that for combination fan and compressor?

 

[jimindenver]

Mine is rated for 3.9 amps at 120v, that's 39 amps at 12v. In reallity it pulls about 35a at 12v.

 

[ZoNiE]

A few folks out there are running 5KBTU AC units with a Honda EU1000i or similar kipor.

 

[SoulRaven]

A few folks out there are running 5KBTU AC units with a Honda EU1000i or similar kipor.

I am going to use a 2,000 watt Generac. I also have heard that same thing about people using the 1,000 watt. But, some have said that it will run it but that is all it will run at a time. In other words, if they run the AC they can't run anything else with it. I wanted to maybe put something else on line  with it. But it remains to be seen just how much it will tolerate.

 

[highdesertranger]

well if anyone wants my opinion, ac is. well I just deleted a paragraph long rant. highdesertranger

 

[sushidog]

I run my 5,000 BTU AC in my Aliner with a 1,200/1,500 watt Triron generator I got from Home Depot online a few years back. It will even run the AC feeding the power through the converter (which uses some of it to recharge the battery). The highest elevation I have run it at is about 6,000ft. but it did fine. Remember as the altitude increases your genny will produce less power - 3.5% for every 1,000 ft of altitude. So at 6,000 ft. it is only producing about 79% of its rated power output. Plus you will likely experience plug fouling above 5,000 ft if no jetting adjustment is made. Honda generators have high altitude jet kits available to prevent this plug fouling and to restore some lost power.

Chip

 

[Canine]

I have an 8000 btu that is an energy star that we use in the bedroom.When we get back home this weekend I think I'll hook it up to my 800 watt genny and see if it will carry it.Just so you know;Humpty Dumpty was pushed.

 

[jimindenver]

You also loose 1% for every 10 degrees above a degree I don't remember. I do know at 10.000 ft you can loose 40% total on a hot day. It's the reason it takes a 3500/4000 to run our roof air, not one of the quiet inverter generators. You would be surprised how many Honda 3000 you see on CL here and cheap too. They wont cut it at 8000 ft much less 10,000.

The solar on the other hand gets a nice boost from the altitude.

 

[wayne49]

You can run a energy star Frigidaire 5000 BTU window shaker directly off of solar if you have enough, we do. Our 5000 BTU unit pulls 410w once the pressure has built up.

Just take three huge 24v panels tracking the sun, a lot of cabling, controller or controllers, a big PSW inverter and a bunch of battery and you can have a good ol time, well as long as the sun is shining. It would be a lot cheaper, easier to handle and convenient to pick up a refurbished Champion 2000i inverter generator for under $400 and a none energy star A/C for $100 and run it as needed. I didn't build our system just to run the AC, I got the AC after I realized we had enough power to do so. All in all the new system will cost a few grand and I had damn well better be able to do some stuff with it. lol

Hi jimindenver. Wondering why you suggest a non(e) energy star A/C? Would it have more tolerance for the generated power? and cheap enough if it  dies? Both?

Thanks.

 

[jimindenver]

The only reason I went with the energy star unit was to get the absolute lowest watts and I can't say that the extra 50 watts was worth it. The standard unit can be picked up here for $25 at the end of the summer. In any case either unit would be fine the the cleaner output of an inverter generator, I do know an MSW inverter makes the energy star unit buzz. It didn't do that on the PSW.

 

[IGBT]

We have four panels and should be able to run our 6000 btu window unit directly off solar (I am seeing 800 watts from our 1080 watt system in the NW and the window unit draws about 500 to 600 watts).   We don't really have enough battery storage though to run it more than an hour or two if on battery.

If Lithium gets mainstream for RVs though...

 

[jimindenver]

Today I was testing the 250w poly panel vs the old 245w mono panel. I used them tracking the sun, each on it's own controller to power the 5000 BTU AC.

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It ran for 4 hours in the 78 degree temps pulling 450w or so.

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Each panel was good for 200w and 17a+ so the batteries were losing the battle ever so slowly. The inverter was pulling up to 35a.

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The voltage on the battery under load held around 12v for the longest time, when I shut it off at 4 hours it was slightly below 12v.

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With all three panels even flat I will expect to run it without loss. I kept it in the sun to make sure the compressor stayed on the whole time. When the shuts down periodically under normal use only the fan runs and whatever losses there are will be addressed until the compressor comes back on. Even with just two panels tracking i could keep it on as long as the sun shines.

This is the longest I have tested the AC and have to say I'm thrilled. I may hook it up here at the house because while it isn't much compared to the central air, it is free.

 

[cdiggy]

That is awesome. So this proves that it is somewhat doable with enough panel and a little conservation!

 

[Canine]

I just tried the 8000btu ac on the HF 800watt Genny.I couldn't find the current draw listed on it,just the energy star rating and the cost per year to operate.Anyway,it started and runs fine.I guess it must draw under 6 amps.