Powering a mini split

[Brasher801]

Ok, I have watched videos till my eyes are crossing and my mind is numb!
I guess i'm just that dense!!
I am installing a 12000 BTU mini split in my Cargo Conversion Toy Hauler. I have a small 110v fridge (Dormer style) and the Mini says it pulls 9.1 AMP (At startup) and reduces down after room temp gets where it satisfies the thermostat. It then cycles on and off.
My question is, if I install 1800 watts of solar on the roof and have 400ah of Lithium Ion, Will I be able to run it 24/7?
I know there are calculators and other sources out there, but I just need some advice on whether I'm headed in the right direction or just full of crap!! Could be the latter. LOL

 

[iamrich]

1800 watts x 80% (realistic factor) is ~1500w x 5 hours gives you 7500w to play with / 24 hours = 312.5 watts per hour. Me say no.... Unless you supplement with a generator or grid.

 

[Brasher801]

Does the fact I'm doing it on a 24v system matter?

 

[schroederjd]

Does the fact I'm doing it on a 24v system matter?

No. System voltage is not a factor. I come to the same conclusion as iamrich. 300w/hr is ~25% duty cycle for a 1200w (10A @ 120V) mini split. Unless you think it will need to run less than 15 min of every hr (and you don't need ANY power for ANYTHING else), it's probably not going to work.

 

[Brasher801]

So, what size battery bank would I need? A trailer full? LOL

 

[iamrich]

So, what size battery bank would I need? A trailer full? LOL

You need more solar. Even if you battery bank is 10 gigawatts, if you don't produce enough power to replenish what you use, you will eventually run out.

So let's say you get the full 1800w out of your panel for six straight hours (like the sun gets stuck right above your panels). You will make 10800w of power which divided by 24 hours is only 450w per hour. It's not enough if your items are running 24/7. If they only cycle occasionally you might be fine, but other wise you just don't generate enough power.

 

[iamrich]

Man I really sounded negative in that last message

You need to figure your usage per day in kwh and then figure out how big your battery needs to be by how long you want it to last if the sun doesn't shine. Then size your array to provide enough solar to charge your batteries to full and power your stuff while charging.

400ahx24vx80% is ~7500W, so your array is probably big enough to replenish it, but not to run other stuff at the same time.

 

[MisterSandals]

I have a small 110v fridge (Dormer style) and the Mini says it pulls 9.1 AMP (At startup) and reduces down after room temp gets where it satisfies the thermostat. It then cycles on and off.

You NEED to figure out how many watt hours you are talking about first. Anything else is pretty much a guess.

 

[Brasher801]

Man I really sounded negative in that last message

You need to figure your usage per day in kwh and then figure out how big your battery needs to be by how long you want it to last if the sun doesn't shine. Then size your array to provide enough solar to charge your batteries to full and power your stuff while charging.

400ahx24vx80% is ~7500W, so your array is probably big enough to replenish it, but not to run other stuff at the same time.

No offense taken. LOL I'm so new to solar I still squeak!! Just looking for some real advice on a forum I figure I will get REAL help. Thanks

 

[Brasher801]

You NEED to figure out how many watt hours you are talking about first. Anything else is pretty much a guess.

All I will be running is the 9.1Amp split, and it is lower after it reaches a desired temp to about 4 Amp. Also the little fridge is 6.2 I think. and again, not running all the time. Other than that, my lights are LED strip lights and a water pump that kicks on occasionally but not much.

 

[MisterSandals]

All I will be running is the 9.1Amp split, and it is lower after it reaches a desired temp to about 4 Amp. Also the little fridge is 6.2 I think. and again, not running all the time. Other than that, my lights are LED strip lights and a water pump that kicks on occasionally but not much.

Then you're just going to need some panels and some batteries. So not much.

 

[NMNeil]

Check your mini split because both of mine are inverter types, and automatically have a soft starter.
Also mine don't cycle on and off, they are on all the time and the compressor just ramps up or down depending on the load.
The highest current draw I've ever seen was just over 950 watts and that's for a 12K BTU unit.

Pioneer® 12,000 BTU 20.8 SEER2 Ductless Mini-Split Inverter+ Air Conditioner Heat Pump System Full Set 115V

Ductless DC Inverter High Wall Mounted Split Air Conditioning and Heating System. Operation Mode: Cooling and Heating. Capacity: 12,000 BTU/Hr. (1 Ton) Efficiency Rating: 20 S.E.E.R. Electrical Specification: 208~230 VAC, 1 Phase, 60 Hertz.

www.highseer.com

Click on the 'technical brochure' at the bottom of the page.

 

[Brasher801]

Check your mini split because both of mine are inverter types, and automatically have a soft starter.
Also mine don't cycle on and off, they are on all the time and the compressor just ramps up or down depending on the load.
The highest current draw I've ever seen was just over 950 watts and that's for a 12K BTU unit.

Pioneer® 12,000 BTU 20.8 SEER2 Ductless Mini-Split Inverter+ Air Conditioner Heat Pump System Full Set 115V

Ductless DC Inverter High Wall Mounted Split Air Conditioning and Heating System. Operation Mode: Cooling and Heating. Capacity: 12,000 BTU/Hr. (1 Ton) Efficiency Rating: 20 S.E.E.R. Electrical Specification: 208~230 VAC, 1 Phase, 60 Hertz.

www.highseer.com

Click on the 'technical brochure' at the bottom of the page.

Yes! correct. Mine is inverter style. Says 9.1 but I know the articles say it goes lower after temp achieved.

 

[Brasher801]

Yes! correct. Mine is inverter style. Says 9.1 but I know the articles say it goes lower after temp achieved.

I bought the 9000 BTU Pioneer Inverter type. Sheet says 960 Watts Max.

 

[iamrich]

Here is my advice. Install it, install your solar (as much as you can fit), install your 400ah 24v battery and see what happens. Just make sure you can supplement with a generator or grid if needed. If you are camping in 80F and want it to be 70F you might be fine, but if you are camping in 105F and want it 70F maybe not.

 

[Brasher801]

Here is my advice. Install it, install your solar (as much as you can fit), install your 400ah 24v battery and see what happens. Just make sure you can supplement with a generator or grid if needed. If you are camping in 80F and want it to be 70F you might be fine, but if you are camping in 105F and want it 70F maybe not.

LOL!! Sound advice!! I plan to install up to 2000 watts. (that's all I can fit) and the 400ah lithium battery. Carry the generator just in case and we will see! Maybe I will need a second 400ah battery. Who knows.

 

[Hedges]

It all depends on average (or steady-state) draw by the mini-split.
PV has to produce all the power consumed. Batteries are mostly to provide power consumed at night.
Hopefully, heat load is less at night and much less power is consumed 8:00 PM to 8:00 AM.

I think I saw spec for one mini-split and power consumption varied 3:1 (900W down to 300W), but BTU varied 8 or 9:1.
That would mean a fraction the efficiency at lower power, and you'd be better off cycling it on and off. Might consume 1/3 as much energy that way.

 

[chrisski]

Then you're just going to need some panels and some batteries. So not much.

I think I detect some sarcasm here.

So, what size battery bank would I need? A trailer full? LOL

Yes I think you need a trailer full. Literally. I'm basing this more on my hot desert Arizona lifestyle than my parent's frigid Maine environment.

Without hard data, here's some numbers. This is also why it makes my head ache doing this without a KWh power requirement.

Batteries: I have 6 volt flooded lead acid batteries. Each 6V battery I have, lets me use 650 wh (54 ah at 12 volts) of power. It actually holds, 1300 wh, but I can't go below 50%.
-If your mini runs at 9.1 amps at 120 VAC, Thats 91 amps at 12 volts per hour, or 1092 whs of batteries. But that is only at start up. So, I would go into it planning on one 6 volt battery per hour you plan to run your AC. This is a VERY POOR ESTIMATE, but kind of gets you thinking if you even want to bother doing the harder explanations.

A/C Draw: The video I watched of the type of rooftop A/C I had pulled 155 amps. The most my 1350 watts of panels have ever made was 74 amps. That means in peak sun, I deplete my batteries by 91 amps an hour. Since your split may pull 91 amps, I'm only losing 17 amps an hour from the battery. My panels may only deliver the 74 amps for 4 hours a day, Before and after, they will steadily rise and fall from 0.

How Long is AC ON: This is important. If I were in Maine, where my parents live, I could probably use the A.C, because honestly, a few times a year I'd turn it on for a few hours around noon with peak production not dipping into my batteries. I am in sunny AZ, where when I turn both my A/Cs on in my trailer, its still unbearably warm inside, so AC is impossible. Well not impossible, I just estimate it would cost me $25,000 dollars and a trailer to power my fifth wheel. $25k buys a lot of nights at an RV resort, and then I don't need to tow an additional trailer.

Locally, on Craigslist, there's the solar trailers on sale from the defunct company. They seem to be good trailers and a local business s owner sold his business, bought one of these trailers and a fifth wheel to travel around the country. That plan will work. He must plan on driving out, dropping his trailer off, then coming back to get his fifth wheel whenever he moves.

My bottom line is each 6 volt FLA battery you buy will give you 650 wh of power. From there, you need a power requirement.

 

[iamrich]

Interested in seeing how the pioneer does. I am looking for one for my garage in the same size.

 

[chrisski]

Interested in seeing how the pioneer does. I am looking for one for my garage in the same size.

Some data on a mini-split would be nice. Perhaps by someone who has one in their house. My POCO gives very detailed data.