Adding a portable air conditioner....no worries, right?

porch13

I'm thinking about picking up a portable air conditioner from Costco for our cabin.  It would be used in the afternoon for a few hours, after the batteries are floating and I'm still getting full sun on the panels.  The AC unit is a Delonghi, and the specs say it pulls under 10 amps.  Since I have over 4,000 watts in panels and a 3,600 watt inverter, I don't think I would have any issues running the AC for a few hours a day.  Nothing else would run at the same time that would ever get me close to the 3,600 watt max on the inverter.  Is there anything that I'm not thinking about that would cause me a problem?  Thanks!

BB.

Sounds OK... Just watch the surge current does not cause the inverter to shut down or cycle on/off/on as the compressor tries to restart.

-Bill

porch13

Thanks Bill!  Fortunately Costco has a great return policy so I can return the unit if anything seems wonky.

Estragon

One thing to watch for / check is a cloud going by in the afternoon and the A/C making the controller rebulk/absorb (or obviously letting the A/C run the batteries down if weather really turns). Setting a long rebulk delay and/or low-ish voltage should minimize that issue though.

porch13

Good points @Estragon.  I'm...how shall I say....hyper sensitive about the system....so I would only run it if I was watching everything.  :-)
I'm definitely going to check my settings, though.  Thank you!

mcgivor

Personally I've pondered the feasibility of air conditioning off grid, only coming to the conclusion, it can be done, albeit at great expense, if done properly. This is with inexpensive inverter mini split systems at my disposal, when the temperature stays above  28°C all night, the unit would need to run too deeply into the battery capacity. For this reason I sleep in my birthday suit with a 12VDC fan on a dedicated system, at least I can sleep, minus the adverse effects of air conditioning.... dehydration.
Perhaps cooling the concrete mass during the day with excess power, in my case, would help with overnight temperatures due to latent heat absorbed during the day, but it seems I survive without, at least so far

mcnutt13579

It is done here in Northern California by a few customers.  It gets cool almost every single night here, dry in summer.  Generally they have overkill arrays and well insulated houses and the AC runs from say noon to 5pm in the high time of summer.  Of course the batteries usually topped out sometime before 11am so nothing is being lost.  I have wanted to hook up some kind of relay to only run AC if ample solar is available but so far no takers on my scheme.  No way I would consider using [lead acid] battery to run AC even for an hour.  I would sooner have them run the generator if they had to have it.  I suppose if somebody has lithium it might work since it will not be damaged by sitting at a lower SoC all night long.

Dave Angelini

The system has to be designed from the start to run cooling at night. It is no different than AC powered refrigeration on a smaller system.
The loads have to be accounted for. I have lived offgrid in the central Sierra for over 25 years with cooling requirements and wild fires. With a fire you can't open windows when it is cool outside because of smoke. We also get a couple weeks when it does not cool off and so it is required unless you like torture.

The Mini-split in N. America made all of this much easier in 2007. Lithium Batteries made it even easier because you can accurately measure Soc and not worry about it. I have a over 100 clients using mini-splits offgrid.

I remember my old window unit being so loud outside and inside that a bear was in the yard and my dog was barking.  I could not hear it.  A very sad day for my wife and the worse for the dog

mcnutt13579

Dave, what lithium battery system are you using?

Dave Angelini

I have a 10 kwh LG but I use the Discover AES (below) along with a few others. Also lead acid when it makes sense. Going to hit 100F here tomorrow.




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porch13

I tested the AC over the weekend at the cabin.  I turned it on around 12:30, just after the batteries went into float, and ran it until around 5:00 (when a tree starts to shade part of my array).  It worked like a charm.  Blew ice cold and pulled about 9.6 amps.  The batteries stayed floating the whole time.  Neat stuff!

Desert Rat

If you're running the A/C on its own circuit, you can use the  AUX function of your Outback inverter or charge controller for worry-free control. A 9.6 amp load can pull your batteries down quickly if it gets cloudy or you forget to turn it off.

http://forum.solar-electric.com/discussion/350889/automatic-control-of-off-grid-mini-split-a-c#latest