Need Help With 48V Off Grid Basic System Please

[S.E.HomeStead]

Hi all,
New to the forum and to solar, I figured I'd bounce my game plan off the more experienced solar users here on this forum.
Thank you in advance to anyone who chimes in.

My off grid situation:
-20' x 8' enclosed, insulated cargo trailer, 160 sq. ft.
-permanently parked in shade under giant 30' x 20' carport
-need to condition the airspace in trailer 24/7
-ample roof space for as many panels as needed
-lots of sun here in South Carolina

My main question is:
Can I run a Midea U shape inverter type 8000btu window unit off a single 48V / 100ah / 5.1kwh server rack mount battery,
using a simple 3kw all in one unit like the EG4, with about 6 x 375w solar panels?

I haven't purchased the Midea yet, haven't purchased any equipment yet.
I'm not dead set on the exact model of all in one unit, nor on the panels (either parts are relatively cheap), but I wanna be damn sure on the battery choice before I plop down nearly $2k with tax and shipping for a single battery.
Due to budget constrains, I'd have to start with only one battery.
However, I'd purchase another one within a few months, and possibly another one after that.

Some extra info:
I'd try to run the Midea on as conservative a setting as possible, maintaining around 75 - 78 degrees inside the trailer 24/7.
It's humid here for around 5 months out of the year, and the a/c will need to run at night for sure. Very different than up north or out west where the air is dry.
Other energy draws are small, like LED lights, laptop, cell phone. Nothing crazy at all besides a/c.
Cooler for food + drinks until second battery.
Winter heat is propane.
All cooking is propane.

Thank you for any input!

 

[Ampster]

I just did a quick Google search on 8000 BTU conversion to kW and came up with between 2 and 3kW. I am sure there are a lot of other variables such as the efficiency of the wall unit and the insulation on the trailer but a gross estimate would suggest that you would need a lot more batteries and solar panels. A cost effective starting point might be more insulation on the trailer and some better estimate of the energy envelope. I have heard mini splits are much more efficient than window units.

 

[S.E.HomeStead]

I just did a quick Google search on 8000 BTU conversion to kW and came up with between 2 and 3kW. I am sure there are a lot of other variables such as the efficiency of the wall unit and the insulation on the trailer but a gross estimate would suggest that you would need a lot more batteries and solar panels. A cost effective starting point might be more insulation on the trailer and some better estimate of the energy envelope. I have heard mini splits are much more efficient than window units.

Thank you for your input!
The Midea 8000btu U shape window unit works like a mini split, inverter type, variable speed compressor, draws a max of 710 watts on high, and as low as under 200 watts on low.
And so basically from what I gather, it uses up to half the watts of even the smallest 5000btu window unit (400 watts).

 

[Ampster]

Okay so 700 times 24 is 16 kWh per day. Now the trick is how many kWhs can you get from the sun, some of which has to charge batteries and some run the Midea? Just 16 hours on batteries would be 11 kWhs. You would need larger than that in battery capacity for cushion. You can do the math but 2250 kW in solar panels is also not going to give you 16 kWhs per day. Maybe for a few days in June but Spring and Fall will be less.

 

[S.E.HomeStead]

Okay so 700 times 24 is 16 kWh per day. Now the trick is how many kWhs can you get from the sun, some of which has to charge batteries and some run the Midea? Just 16 hours on batteries would be 11 kWhs. You would need larger than that in battery capacity for cushion. You can do the math but 2250 kW in solar panels is also not going to give you 16 kWhs per day. Maybe for a few days in June but Spring and Fall will be less.

Well that is all worst case scenario math, which is good if money is no object.
The Midea only draws 710 watts on high with fan on high.
I was planning to leave it on low to keep my small 160 sq. ft. space comfortable. On low it should be drawing something less than 200 watts with compressor on, and the compressor won't run 24/7 in a insulated space.
My 160 sq. ft. space is a lot smaller than the 350 sq. ft. the unit is rated for.
I'm wondering if I can get away with just one 5.12kwh battery for a few months, with no other significant draws than the a/c.

I'd love to be able to just throw $15k at the situation, but unfortunately I will have to build the system one battery at a time.
I could supplement with a generator until I have enough batteries.
I can add more panels and a second 3kw all in one unit after buying second battery, for that extra nice cushion.

 

[Ampster]

I'm wondering if I can get away with just one 5.12kwh battery for a few months, with no other significant draws than the a/c.

I did the worse case math, so now you have the tools to answer that question yourself. The simple answer is that you can get away with one battery but it will not work every day and some days you are going to be warmer than other days.

 

[S.E.HomeStead]

I did the worse case math, so now you have the tools to answer that question yourself. The simple answer is that you can get away with one battery but it will not work every day and some days you are going to be warmer than other days.

Thank you. I needed to hear that.
Do you think it's possible to supplement with running a generator for a few hours (like a Honda EU2200i) on cloudy days to top up the battery for the night?
Can the generator 120V just be plugged into the EG4 unit's AC input?
Thank you!

 

[Ampster]

I don't know much about the EG4. If it has a generator input that is 120V it should work with the Honda. I do not know about the plugs or receptacles on those devices. You will have to read the specs yourself.

 

[Riwall]

Thank you. I needed to hear that.
Do you think it's possible to supplement with running a generator for a few hours (like a Honda EU2200i) on cloudy days to top up the battery for the night?
Can the generator 120V just be plugged into the EG4 unit's AC input?
Thank you!

That should work fine. You will need to lower the AC charge setting to avoid overloading the small generator.