Yet another minisplit setup question

[phoenixmoon]

Greetings all.

I live off-grid in the Mohave Desert in Arizona which means plenty of sun (even in the winter months!) but also means it gets very hot.

I'm looking to set up a minisplit in my place for this summer but unsure what I need.

I currently have 2x12V/200AH lithium ion batteries that run everything great. I shut the inverter off at night to save on power, but it's not really necessary...

Not sure what my panel situation is other than to say that it's a lot. It's 4PM on a clear sunny day and my app is telling me I'm getting 19.5 solar volts, 6.1 solar amps and 114 watts of solar power at float. I'm generally at 100% SOC by 8/9AM this time of year, earlier when the sun is coming up.

I'm not opposed to adding panels, or even running a separate bank if need be.

What I'm looking for is a setup that allows me to keep my place at a comfortable temperature all day and all night all year round. I have an on-board generator, but it's loud and irritating and I almost never use it, so I'd like something that runs entire off of solar.

My fifth wheel is 39 feet.

So what I want to know is:

• How much minisplit do I need? (BTUs / SEER)
• How much battery do I need to run it?
• How many / what kind panels do I need to run it?

Like a lot of people I'd assume I still have a lot of trouble wrapping my head around the algebra of energy production. Any guidance you can give me would be greatly appreciated.

 

[sunshine_eggo]

I don't have an answer for you, but I have something to think about.

BTU to SEER to Watts:

12000 BTU / SEER = Watts

12000 BUT / 20 SEER = 600W

However, at peak output, your minisplit will require MOAR than 600W for sure, yet it will likely run at less when simply maintaining a set temp.

You can calculate a heat load here:

Box Heat Loss

Sheet1 Inside, °F,75,°C,10 Outside, °F,120,°C,-6 L, ft,W, ft,R,BTU/h,Comment,L, m,W, m,RSI,W,Comment E,8,8,3.4,847,E,2.45,2.45,0.70,136 W,8,8,3.4,847,W,2.45,2.45,0.70,136 S,39,8,3.4,4129,S,11.93,2.45,0.70,663 N,39,8,3.4,4129,N,11.93,2.45,0.70,663 Roof,39,8,3.4,4129,Roof,11.93,2.45,0.70,663 Floor,39

docs.google.com

Save a copy for yourself.

Assuming R4 all over (RV insulation is horribly inconsistent AND misleading - I figure 4 is a safe assumption):



You need 16385 BTU/h to maintain a 75°F interior temperature in 120°F ambient.

Note that this is in the SHADE. This does not take into consideration the 1000W/m^2 that's hitting every surface exposed to the sun (good news is that solar panels are shade!).

If you have 2-3 15K BTU roof units, you likely don't need 2-3 15K mini-split units.

Gut says a 18,000 BTU unit would likely work.

Since we don't have usage data, let's assume worse case...

18000/20 SEER = 900W... 900W continuous use - that's about 21.6kWh and about 4kW of solar even in Mohave county.

Good news is it probably won't come anywhere near that.

Like I said, I don't have an answer for you, but the above are some of the tools and relationships used when running these kinds of calculations.

Good luck!

 

[Solarmadness]

Greetings all.

I live off-grid in the Mohave Desert in Arizona which means plenty of sun (even in the winter months!) but also means it gets very hot.

I'm looking to set up a minisplit in my place for this summer but unsure what I need.

I currently have 2x12V/200AH lithium ion batteries that run everything great. I shut the inverter off at night to save on power, but it's not really necessary...

Not sure what my panel situation is other than to say that it's a lot. It's 4PM on a clear sunny day and my app is telling me I'm getting 19.5 solar volts, 6.1 solar amps and 114 watts of solar power at float. I'm generally at 100% SOC by 8/9AM this time of year, earlier when the sun is coming up.

I'm not opposed to adding panels, or even running a separate bank if need be.

What I'm looking for is a setup that allows me to keep my place at a comfortable temperature all day and all night all year round. I have an on-board generator, but it's loud and irritating and I almost never use it, so I'd like something that runs entire off of solar.

My fifth wheel is 39 feet.

So what I want to know is:

• How much minisplit do I need? (BTUs / SEER)
• How much battery do I need to run it?
• How many / what kind panels do I need to run it?

Like a lot of people I'd assume I still have a lot of trouble wrapping my head around the algebra of energy production. Any guidance you can give me would be greatly appreciated.

I have a 30ft trailer in Quartzite AZ that I installed a mini split in. 9000 BTU,125v unit. It works good but I have to run a fan to get the cool air back to the rear bedroom.I wish I installed a bigger Unit.These trailers get hot in the summers.18000 BTU seems like it would take care of this area.Also works good in Winter.I think your going to need 3x your current batteries and more solar panels for sure.Im running a Senville Unit.I think there are better units out there.