Power for a small air conditioner

First Question on this site.

I am trying to make a generator purchase decision, however I am not very electric knowledgeable.

Is the AC 300 able to power a small room portable air conditioner 12000 BTUs (Ashrae), 1250 watt, 115 volts, CEER 12, plug type 5-15P, BTU rating (DOE) 10000, room size 300 sq ft., North Texas weather in summer can be 100+?

If yes, any suggests on amount of solar power and /or batteries needed to keep this AC running 24/7?

Thank you for your help.

Yes. Anything that has a standard 115v wall plug this unit will run. Additionally it has the enough capacity to run a couple other things at the same time. You wouldn’t want to plug in 2 or 3 AC units at once but it will definitely run 1 with power left over. if the AC uses 1250 watts that basically means in 1 hour it will use that much. so a 1250 watthour battery would last 1 hour. a 2500 watthour battery would last 2 hours and so on and so on. its not a perfect system either, a 1250 watt AC unit would probably need more like a 1800 or 2000 watthour battery for an hour of run time. So if you had at least 1250 watts of solar and the sun shined perfectly 24/7 you could run indefinitely.

Thank you for your response. Now that I know the generator can do the task needed, I can now tackle the task of figuring out what number of solar panels and/or batteries I need to keep the system going on Solar 24/7. Any thoughts on that from anyone would be appreciated. I do realize sunny weather isn’t consistent.
Thanks again Doecliff. You helped me move forward.


I would buy a watt meter. There’s a popular one called kil-a-watt that you plug into the wall then you plug your device into it. Leave it run for a day and see how much energy you used. Or even better see how much you use during non solar hours and sunshine hours. Assuming you have a full battery when the sun goes down you need enough battery to get you through to the morning with some fat built in. say 20% remaining then the sun comes up and you can both charge battery’s and run the AC. I would bet that you need the maximum amount of solar that the AC 300 will take to do what you want. Good news is you can still use the grid power if its cloudy. let me suggest this guy.

He’s also a member here.

So the AC300 with the B300 battery is going to have 3,072Wh of capacity. Probably best to assume 85% of that since there will be some loss (as it is not 100% efficient) - so let’s say 2600Wh.

Assuming your AC uses 1250 Watts per hour (it probably doesn’t run always on as when it gets to the setpoint it turns off for a while, but we can assume for simplicity sake).

You will get about 2 hours of run time. With a second B300 you will get 4 hours of runtime.

You can attach up to 4 batteries. This will give you 8 hours of runtime.

As you can probably see - drawing 1250W is quite a lot of power to use 24h.

Looks like the input is 2400W max solar (up to 145V). If you could bring in more power than is being used though daylight hours then your batteries would stay at 100% all day. At night the sun goes down and the batteries would be required to keep the AC running.


Thank you for your input and suggestions. I plan to buy the tool and read the book. The subject is interesting and maybe even needed knowledge these days.

Dr. Torch:

Also thank you for your insight and number crunching. It really added to my understanding.

I think the AC300 would require the purchase of more batteries and panels than I wish to purchase. Tomorrow I will read up on the EP500 Pro and see if that might work.

Thanks again guys.

Like Dr. Torch said. The 1250 watts isnt being used 24/7. The AC (compressor) cycles on and off. Having an accurate idea of how much power you really use matters. An AC unit is one of the larger things a typical consumer uses with regard to electrical load.