diy solar

diy solar

230v for mobile minisplit

htx_overland

New Member
Joined
Aug 7, 2020
Messages
16
HI,

After a lot of debate, we're planning to go with a high SEER minisplit for our rig. Seems like it is cheaper to buy a higher efficiency unit than a larger power system(and we running short of room for panels). But....the high SEER units are almost all 208/203 single phase.

Looked at a lot of options, but have it paired down to 3. Right now the options are all built around victron, but may look at brands once the general design is a little further down the line. Pricing out these options they are all within about 10% of each other.

My battery bank is 24v.

Wanted to see if the forum has experience that might help prioritize the options - or can kick in an even better option.

1] Dedicated 240v inverter for minisplit.
<> Multiplus 24/3000/70 120V for 120v needs & shore power /charging
<> Phoenix 24/3000 240v for the minisplit
+ Pretty simple design
+ Can turn off the Phoenix when AC is not in use to minimize power draw
+ Splitting the load between 120 & 240 load may keep the inverters closer to their peak efficiency (I think max eff is at about 20-30% load)
+ Highest max efficiency of the options (~94%)

2] Dual Multiplus in split phase
<> 2x Multiplus 24/3000/70 120V
+ Potential redundancy for 120v (would probably require swapping, but gear would be there)
+ ?? might have 2x the charging power from shore - most of these options
- Higher base load (2x the idle consumption) if 120v are shared on different 120v legs
- Or legs are imbalanced with 1 Multiplus only having the 2nd leg of the AC so it can be shut off

3] Larger Multiplus with Autotransformer
<> Multiplus 24/5000/120
<> Autotransformer 100A
+ Like 1] - simple design
+ More shore power / charging vs 1]
+ More 120v capacity if I needed it when the AC is off
- Can't cut the 0 load/search loss as 1] (30w/10w vs 20w/8w)

Thanks!
 
Random notes...
* If you're running dual multiplus units, you can't just shut one off (they'll both shut off). It requires you to reconfigure them as standalone units
* A single 120v multiplus limits you to 120v input (50 amps); you CAN put another AT in front but the minimum powerassist current setting will be double as a result (may limit you to 30 amp 120v service; 15 amp 120v may not work). BUT, 120v 50 amp is probably enough... this does cause a power imbalance at the shore pedestal, though
* Yes dual MP units will double your charging capacity
* Yup you have to watch for imbalance between L1 and L2 with option 2. You don't want the mini-split on both, microwave on L1, and toaster on L1, for example. Don't forget, that's 3kVA max sustained each leg at ~room temp or 2400 watts (less if they're hotter / in an unconditioned space).

I have option 2 in my rig, but with quattro 5k's. And mini-split. I rarely go over 1500 watts combined and sometimes peak very briefly at 4500 watts combined (AC, microwave, toaster, fridge, computers, TV, ...). My loads are well-balanced. I can connect to 120v 15a through 240v 50a and I can adjust my power assist all the way down to 13.4 amps (which means a 15 amp plug is fine, as is my 3000 watt generator).
 
Random notes...
* If you're running dual multiplus units, you can't just shut one off (they'll both shut off). It requires you to reconfigure them as standalone units
* A single 120v multiplus limits you to 120v input (50 amps); you CAN put another AT in front but the minimum powerassist current setting will be double as a result (may limit you to 30 amp 120v service; 15 amp 120v may not work). BUT, 120v 50 amp is probably enough... this does cause a power imbalance at the shore pedestal, though
* Yes dual MP units will double your charging capacity
* Yup you have to watch for imbalance between L1 and L2 with option 2. You don't want the mini-split on both, microwave on L1, and toaster on L1, for example. Don't forget, that's 3kVA max sustained each leg at ~room temp or 2400 watts (less if they're hotter / in an unconditioned space).

I have option 2 in my rig, but with quattro 5k's. And mini-split. I rarely go over 1500 watts combined and sometimes peak very briefly at 4500 watts combined (AC, microwave, toaster, fridge, computers, TV, ...). My loads are well-balanced. I can connect to 120v 15a through 240v 50a and I can adjust my power assist all the way down to 13.4 amps (which means a 15 amp plug is fine, as is my 3000 watt generator).
Thanks appreciate the thoughts and for how #2 would actually work.
 
If you are setting up a dedicated inverter just for the ac, you don’t need split phase. You can use one of the low cost European inverters with 230V output. It is good if you can get a smart one that has settings to change to 60Hz.
 
If you are setting up a dedicated inverter just for the ac, you don’t need split phase. You can use one of the low cost European inverters with 230V output. It is good if you can get a smart one that has settings to change to 60Hz.
Thanks! That's kinka what I was going for with option 1]. You can go with different price points depending on efficiency. I think this is the cleanest approach and probably the most efficient - especially in the winter when charging times are short and I'll probably be using diesel heat vs e-. Only real downside is that the 2nd inverter can't swing to 120 if need be.
 
ok this has me confused and i am sure others have been confused as well
a European 230 wiring consist of 1 neutral wire 1 ground wire
and one 240volt wire (not two legs of 110v)
a north American 220 volt consist of ,one leg 110v second leg 110v and third wire ground.
so to be sure of ordering the right inverter (or appliance) a European 240v is not the same as a US 220v and a European appliances will not work in the US and a US appliance will not work in Europe, unless you have a adapter/transformerhttps://images.app.goo.gl/oieEN9nCymnmBk3t6
 
Last edited:
ok this has me confused and i am sure others have been confused as well
a European 230 wiring consist of 1 neutral wire 1 ground wire
and one 240volt wire (not two legs of 110v)
a north American 220 volt consist of ,one leg 110v second leg 110v and third wire ground.
so to be sure of ordering the right inverter (or appliance) a European 240v is not the same as a US 220v and a European appliances will not work in the US and a US appliance will not work in Europe, unless you have a adapter/transformerhttps://images.app.goo.gl/oieEN9nCymnmBk3t6
Thanks! I think you are right. You'd need a 230v split phase inverter for option 1] for any mini-split designed for the US market. And I don't want to think about importing a minisplit. While there are a number of 230v split phase inverters on the market, pretty sure the Phoenix 230v listed above is not split phase.
 
i have a 110v and a 220v mini split in my home that is just as efficient as each other
i do plan to change out my window unit to a mini split in my trailer and avoid any extra wiring or equipment
 
i have a 110v and a 220v mini split in my home that is just as efficient as each other
i do plan to change out my window unit to a mini split in my trailer and avoid any extra wiring or equipment
Nice! About what SEER?
 
the 220v is a 19 seer the 110v 18 ,not the greatest but still more efficient than running my central AC unit i got them from Mexico super cheap prices
 
ok this has me confused and i am sure others have been confused as well
a European 230 wiring consist of 1 neutral wire 1 ground wire
and one 240volt wire (not two legs of 110v)
a north American 220 volt consist of ,one leg 110v second leg 110v and third wire ground.
so to be sure of ordering the right inverter (or appliance) a European 240v is not the same as a US 220v and a European appliances will not work in the US and a US appliance will not work in Europe, unless you have a adapter/transformerhttps://images.app.goo.gl/oieEN9nCymnmBk3t6
Wiring into a home, where you need a grounded neutral that is split phase with 120v on each side is one thing, but a motor designed for 208/230V will not care if it is split phase or not.
The neutral and hot would connect to L1 and L2, and the ground would hook to ground.
I promise.
It works fine.
I will make a video showing a brand new 240V minisplit connected to a euro 230V inverter if you like.
 
I don't think it's safe to assume that all 240v minisplits will work without the neutral; like ranges, it may utilize 120v for control circuitry. Verify the specific minisplit doesn't have a connection for neutral.
 
This is interesting to me, because I'm in the process of getting a final design for my rig, maybe 2 of the Quattro units and I probably want to add a second AC, whether 120v or 240v. I don't want to back myself in a corner for options and not buy the right setup.
 
Wiring into a home, where you need a grounded neutral that is split phase with 120v on each side is one thing, but a motor designed for 208/230V will not care if it is split phase or not.
The neutral and hot would connect to L1 and L2, and the ground would hook to ground.
I promise.
It works fine.
I will make a video showing a brand new 240V minisplit connected to a euro 230V inverter if you like.
i am no expert in any means but if you wire a appliance that has a transformer in it like a stove (maybe to make a clock work) a mini split that has a 110 blower motor ,how does that work with out a dedicated neutral ? or the neutral being energized by a hot leg ?
 
I was looking at the Mitsubishi. https://hvacdirect.com/hvac/pdf/M-FH_Condenser_Install.pdf

They show L1 & L2 120v leads. Didn't see anything that show a single 230v approach.

That *is* a 240v approach. There's no third Neutral line. A 240v single phase inverter should drive that ODU just fine. Same for the IDUs. L1 will go to "hot" and L2 will go to "neutral" of the single-phase inverter. @Supervstech please correct me if I'm wrong (as I've not done this before; but the theory seems sound).
 
i am no expert in any means but if you wire a appliance that has a transformer in it like a stove (maybe to make a clock work) a mini split that has a 110 blower motor ,how does that work with out a dedicated neutral ? or the neutral being energized by a hot leg ?
A 240V minisplit will have a 240V indoor blower.
There is no neutral connection on a 240V minisplit.
 
I think I am am beginning to understand. Summary below.

Here is the installation instructions for the NA model:
1621552629000.png
As Supervstech notes, there is no neutral - just L1 & L2- & blower looks 230 as well. The L1 & L2 would show ~220-240 in NA residential.

Curious what S3 is? Control?


Here is the installations for the EU model:
1621552864400.png


Here the L/N which should give a similar 230V spread.
1621552987100.png

Similar S1/2/3 connection. Still no clarity on the S3 wire.

Feels like it could work. But not sure I'm confident enough to bet on it.
 
Back
Top