DC powered mini-split versus AC, efficiency worth it?

[Plum Crazy Rob]

I have experience with mini splits and they can be quiet (inside unit) when at lower speeds.

Great just making sure

 

[Swing]

I don't hear mine.
I only know that it's working because the room temperature is where it should be. And I sit 15' from it.

Looks like the go-to option for my situation but probably getting really unhappy shipping quotes.
Maybe worthwhile to import multiple units for some other Western-European consumers / forum members

 

[Danke]

I don't hear mine.
I only know that it's working because the room temperature is where it should be. And I sit 15' from it.

Charge your hearing aid batteries.

 

[Swing]

Charge your hearing aid batteries.

You have different experience? With this Hotspot or other 48v DC minisplits?

I am sure you can hear it, but the question is if it is acceptable or not

 

[robby]

Charge your hearing aid batteries.

5 Speed settings on My Panasonic's.
1-3 are not even Audible. 4 is a bit audible, like the sound of light rain.
Speed 5 is Audible like a someone whispering in a room.
We rarely use speed 5 because it blows too much direct cold air at us.

 

[Plum Crazy Rob]

Please note that I also look at using it for heating in Western European climates.
So heating when it is -5 or -10 degrees Celcius outside. I am sure they will work, but probably much less efficient than the AC powered minisplits I have been usiusing

So Swing....Is -5 or -10C your Winter norm, or your "extreme " like it is here for me?? I ask since NONE of the DC units are specifically Cold-Climate?? As you indicate, sure the standard units operate that cold, but their COP will be gradually dwindling towards 1.0 / resistance heating (You indicate you don't have enough AC power for THAT though)

Edit: A giant flipside would be a Mitsubishi or any other properly designed Cold Climate unit will be running resistance pan and compressor sump heaters at those temps.

Maybe leading you to Inverter/Battery -> Mitsubishi Cold Climate if power efficiency is your goal?? Although installed / warranted cost for Mitsubishi can be 5-10x others...

You haven't mentioned COST so not sure if that is a parameter for you.

 

[timselectric]

Charge your hearing aid batteries.

Lmao
My ears are one of the few things that still work perfectly.

 

[Swing]

So Swing....Is -5 or -10C your Winter norm, or your "extreme " like it is here for me?? I ask since NONE of the DC units are specifically Cold-Climate?? As you indicate, sure the standard units operate that cold, but their COP will be gradually dwindling towards 1.0 / resistance heating (You indicate you don't have enough AC power for THAT though)

Edit: A giant flipside would be a Mitsubishi or any other properly designed Cold Climate unit will be running resistance pan and compressor sump heaters at those temps.

Maybe leading you to Inverter/Battery -> Mitsubishi Cold Climate if power efficiency is your goal?? Although installed / warranted cost for Mitsubishi can be 5-10x others...

You haven't mentioned COST so not sure if that is a parameter for you.

-5 or -10C is rare in these days but happens at least once a winter. Typically more like 0 to 10C

I have been working with mini-splits which still provide a reasonable COP in those temperatures and typically keep working until -15C. The Hotspot also works until -15C I have read, but I would like to know either the COP or the heating output at -7C. Because -7 is tested for a lot of heatpumps and minisplits.
But probably it isn't available for these DC minisplits.
Anyway, maybe I get some useful data from Hotspot or Deye.

I am willing to offer a bit of COP in low temps for the overal idea of the house to work. But if the numbers are bad and the units are noisy, then we are just making life hard for ourselves.

There is AC power available from the grid, it would just be about using the lowest entry connection to the grid that is available. That saves some money, but more importantly is welcomed a lot in this day and age because of all the grid congestion that we have.
So I am looking at it from a wider perspective, and this would be great for holiday homes and tiny houses.
In that sense I'm doing this project also a bit as a study.

Basically I am trying to sell the idea of a 48v DC (holiday) home, with battery and solar, and the tiniest grid connection. Which works for these small houses with most of the tech in one area (short cables for the power hungry stuff)
If there seem to be too many obstacles, the second best plan is the complete opposite. Completely hooked onto the grid, everything AC, possibly even without solar, and just use the cheapest hourly prices in the day.
Both options work great for a home that is usually rented out in the times that energy is more available and cheaper.

When it comes to cost, at this point I think there won't be much difference in cost of importing a Hotspot minisplit than to just install a regular good mini-split and an inverter. It could be that something like the Deye 48v minisplit or some other comes around much lower than the Hotspot, for the whole thing to become cheaper.

 

[Plum Crazy Rob]

Basically I am trying to sell the idea of a 48v DC (holiday) home, with battery and solar, and the tiniest grid connection. Which works for these small houses with most of the tech in one area (short cables for the power hungry stuff)

Well THAT sounds like Tim's house. CAPITALIZE BATTERY and SOLAR lol.

I have the Deye hybrid units but doesn't sound like you lean towards them. I will point out the 24k unit did pass US EPA Cold Climate testing although it's neither designed nor should it be used for that day in day out. I mention this because it appears the Deye 48v unit is extremely similar including specs the same Panasonic compressor (5RD198). So you'd imagine the 48v just has additional voltage boost (?) designed in. COP at 5F of 1.8 not fantastic but ok for extreme situations.

 

[Swing]

@Plum Crazy Rob You mean you have the EG4 hybrid which looks like the Deye 48v inverter in terms of specs?
How noisy is it on the inside and outside?

 

[Plum Crazy Rob]

Yes exactly. I have Deye / EG4 hybrids, 1 24k and 2 12k BTU. I threw the 40db number out just as an upper limit on "HIGH" speed, thinking of the 24k. The 12k units are definitely quieter, probably since ultimately less air is being moved.

We have touched as low as -20C, and the 12k units I installed this fall had no problems with that on HEAT. Since they are on bedrooms, I have run them overnight on AC power as needed, using 2-3 Kwh total a night. I've had the 24k on a main living area since 1/1/23 and it's performed spectacularly.

Edit: lower lowest operating temp to -3F / -20C

 

[jdanderson]

I have a 20kw Victron inverter set up, with 20kw PV input from panels, and a 75,000 watt hour battery bank.
I'm installing two mini-split heat pumps (AC only versions) in my house. They will be inverter type mini splits that ramp down and consume low wattage once the building is conditioned.
For my shop building, I'm installing a 24k BTU hybrid mini-split heat pump.
I'll run six panels (2400 watts) of DC input, and will also run a 240v AC input from my main system.
The shop will mostly only be used during the day, when PV input can power the mini split.
AC can supplement through the night or on cloudy days.

Doing it like this preserves my main system for the shop and the house.
Yes, everything is coming from solar, but having the shop climate control separate keeps from taxing my main system most of the time.

 

[SilverbackMP]

The auto/metal fabrication area of my shop (with two 12 foot doors). 28x36 foot area.

One 24k Mitsubishi or two 12ks? Two would be about a grand more expensive and simpler hook up but two would maybe provide better distribution, redundancy, and perhaps be more energy efficient.

Note that will be another 12k in the wood working portion of the sho (20x36 minus a bathroom area).

 

[Bluedog225]

Deleted

 

[timselectric]

The auto/metal fabrication area of my shop (with two 12 foot doors). 28x36 foot area.

One 24k Mitsubishi or two 12ks? Two would be about a grand more expensive and simpler hook up but two would maybe provide better distribution, redundancy, and perhaps be more energy efficient.

Note that will be another 12k in the wood working portion of the sho (20x36 minus a bathroom area).

You had me sold, at efficiency and redundancy. lol