Is it better to have two?

johnim · Jun 7, 2022

Anyone using two minisplits in a bus or rv with separate air handlers vs one larger unit with two air handlers. I wanted a 230V unit but size and cost wise it was easier to go with two separate 12kw units. Also I have the new EG4 3kw inverter and the matching 4.8kw 48V server battery and hope it's enough for them with at least 2kw solar after typical losses. If it's not enough may end up adding another 3kw inverter and/or battery but i didn't want to buy too big and take the running loss which is probably higher in the 6kw....or maybe not. I seem to remember Will testing the 3kw and it was almost 80 watts.

Bobert · Jun 7, 2022

johnim said:
Anyone using two minisplits in a bus or rv with separate air handlers vs one larger unit with two air handlers. I wanted a 230V unit but size and cost wise it was easier to go with two separate 12kw units. Also I have the new EG4 3kw inverter and the matching 4.8kw 48V server battery and hope it's enough for them with at least 2kw solar after typical losses. If it's not enough may end up adding another 3kw inverter and/or battery but i didn't want to buy too big and take the running loss which is probably higher in the 6kw....or maybe not. I seem to remember Will testing the 3kw and it was almost 80 watts.

The size of your inverter is less of an issue than the size of your battery. I have a travel trailer with a 48v 3500w AIO with 5k of battery I can operate my 15k rooftop ac with no problem. The problem is that with a continuous draw of 12 to 1300 watts the battery will be flat in just over 3 hours. I have 2100 watts of solar but it is oriented flat on the roof so if I can manage to park in full sun I can make more solar than my ac will use but only for a few hours a day. Cloudy days forget it I will get half production in peak hours. I say all this because at full blast your 2 mini splits will probably use as much power as my roof top unit (only with 3 to 4 times as much cooling power) most folks I have heard of that do dual mini splits have between 2 to 3 times as much battery as I have and twice the solar or some sort of method of tilting the panels. My opinion is that as system with the specs you have mentioned will work but not for very long. You will need to practice power management when running the mini split but that’s not a big deal as you probably already do that when camping with 30 amp shore power.

johnim · Jun 7, 2022

Well good to know. Thanks for the insight. I have 20 panels coming. Plan 10-12 on top depending on arrangement. I'll look and see what I get with that and add as needed.

Bobert · Jun 7, 2022

I raised my array 8” so I could clear all the vents on my travel trailer and get some ventilation under the panels. If I had the big bucks I could mount 12 400watt panels up there and have 4800 watts.

johnim · Jun 8, 2022

That's what I have with the 20. Accounting for 85% efficiency that's 4kw. I was planning 2 rows of six on either side but that is not going to look good on this bus so will run them side by side on the middle rails which puts them 1" up in the middle but drops off to about 4" at the ends which will be tied down. I'm looking at attaching hinges for five panels on either side which can be stowed while driving and raised with hydraulic door lifters when stationary. So in that case would be 4S4P 4kw best case scenario. But if I do that will probably get another EG4 battery and another matching inverter. May need it anyway for the washer and dryer I want to add.

Bobert · Jun 8, 2022

johnim said:
That's what I have with the 20. Accounting for 85% efficiency that's 4kw. I was planning 2 rows of six on either side but that is not going to look good on this bus so will run them side by side on the middle rails which puts them 1" up in the middle but drops off to about 4" at the ends which will be tied down. I'm looking at attaching hinges for five panels on either side which can be stowed while driving and raised with hydraulic door lifters when stationary. So in that case would be 4S4P 4kw best case scenario. But if I do that will probably get another EG4 battery and another matching inverter. May need it anyway for the washer and dryer I want to add.

My front panels were a pit to close to the front to not be in danger of ripping off in the headwinds when towing so I built an airfoil in the front and skirted the panels with some leftover aluminum that my dad had. I intend to paint the skirting white so that the array becomes mostly invisible.

OffGridInTheCity · Jun 8, 2022

Agree with @Bobert - its not the inverter size as the bottleneck. I have a 7 x 14 cargo trailer -> camper with 1" foam-board (R5) insulation and 9,000BTU Senville. It takes about 6kwh/24hrs for moderate temps (40F low, 90F hi) to heat & cool and maxes out at about 1100watts. You rig is (guestimating from pic) is at least twice as large and probably not any better insulation - so I'd say you're in the range of 12kwh/24hrs. 3 x 4.8kwh batteries would give you a shot at 24hr run-time.

240v vs 120v - they make transformers to convert 120v (from your inverter) to 240v - I don't see this as a big or even expensive issue.

Some pros with 1 mini-split + some small fans to push air in the corners is one unit inside/outside and BTU can be sized for what you need, all-around a bit simpler.
Some cons with 2 x mini-splits is 9000BTU is about the smallest which is 18,000BTU which is probably oversized, you have to mount 2 separate units inside/outside, and could hit 2200w now and then with both running - not much headroom on a 3000w inverter.

I have a 3000w MPP Solar 3048LV and with everything on, 3000w is not enough - we have to be careful when cooking. Maybe buy a bigger unit with 240v/120v such as MPP Solar 6000w instead of the 2nd mini-split

johnim · Jun 10, 2022

Well if nothing else my system can expand easily for the right amount of cash. ???

johnim · Jun 10, 2022

oh just received my solar panels...used santan solar 240 watts so measured open circuite with one at about 1315 and it was putting out 34.5 V max so for the price of $42.5 for each panel I'm impressed.

GLC · Jun 10, 2022

Not in a van but i have two minisplits 110 units being powered off of one 4000/8000 Giandel inverter in my home. Same inverter also supplyies power to 2 fridges, 1 small freezer, couple of tvs, washer, microwave, lights, etc.

johnim · Jun 10, 2022

well my inverter is 3000 max so this is where I'm at. if I have to get another 3kw inverter it's still only the price of the what the 6kw was in the first place and I don't think I will really have lost out bc the EG4s are made to easily run in parallel and I can even get 240V out if I did that.

johnim · Jun 10, 2022

OffGridInTheCity said:
Agree with @Bobert - its not the inverter size as the bottleneck. I have a 7 x 14 cargo trailer -> camper with 1" foam-board (R5) insulation and 9,000BTU Senville. It takes about 6kwh/24hrs for moderate temps (40F low, 90F hi) to heat & cool and maxes out at about 1100watts. You rig is (guestimating from pic) is at least twice as large and probably not any better insulation - so I'd say you're in the range of 12kwh/24hrs. 3 x 4.8kwh batteries would give you a shot at 24hr run-time.

240v vs 120v - they make transformers to convert 120v (from your inverter) to 240v - I don't see this as a big or even expensive issue.

Some pros with 1 mini-split + some small fans to push air in the corners is one unit inside/outside and BTU can be sized for what you need, all-around a bit simpler.
Some cons with 2 x mini-splits is 9000BTU is about the smallest which is 18,000BTU which is probably oversized, you have to mount 2 separate units inside/outside, and could hit 2200w now and then with both running - not much headroom on a 3000w inverter.

I have a 3000w MPP Solar 3048LV and with everything on, 3000w is not enough - we have to be careful when cooking. Maybe buy a bigger unit with 240v/120v such as MPP Solar 6000w instead of the 2nd mini-split

fyi that is not my rig i have a 37' thomas saftliner that I just sprayed with insulation and will add more to hopefully get to R8-10 conservatively. There are also no windows as of yet except in the front and rear. Also these minisplits are high SEER 22 and they will gradually ramp up as needed. It will likely be that only one unit needs to be on high at a time unless I'm in the desert. But yea not much headroom for planning other basic things like microwave or conduction burner.

Is it better to have two?

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