Solar powered mini split vs just using inverter and batteries with old mini split.

[Zwy]

I am currently remodeling other areas of the shop so I've got some time as the PV and HVAC industry seem to be rapidly evolving. My top 3 choices for replacing this mini split are as follows.

1. Cheap Pioneer (or one of the clones) with a good warranty, wifi, good low temp heating performance. The 120v 12,000Btu units are crazy cheap these days around $700-$800 and would be easy to run off an inverter.

I run a 12K Pioneer floor mount. Very little power draw. I prefer 240V simply to keep loads on inverters balanced plus SEER/COP is better.

I do have a 120V unit for my truck camper. That only has the one inverter.

2. EG4 12k hybrid solar mini split. I really like the idea that a couple panels can panel this unit without the grid or a inverter. The app and wifi look great. Line set is too short and its a lot more expensive than the Pioneer.

Some issues with the EG4 seem to be clouds can cause the unit to shutdown and not restart. It will switch to AC power if you have AC hooked up but it seems the unit has over a 100W standby draw with AC connected.

My Pioneer when running during the day might only draw 300W.

3. Hotspot 12 or 15k. I've almost ruled this one out due to price and performance.

Hotspot 12K BTU compared to a Pioneer 12K BTU

Hotspot cooling COP is 5.65 (Hotspot rounded up)
Pioneer 240V cooling COP is 6.00

About a 8% difference. Of course, if battery bank and PV are large enough, it probably isn't a factor with long summer days.

I noticed a heating COP of 3.69 listed on the Hotspot and for the Pioneer it is 3.23. Somebody is fudging numbers as HSPF for the Hotspot is 9.6 and the Pioneer is 10. If you multiply HSPF times 0.293, you will see the Hotspot is 2.8 for heating COP and the Pioneer is 2.9

 

[n2aws]

I must be the odd one as I don't see the reason for a dedicated PV system to run a mini split..........

If your breaker panel or wiring is not up to the task, maybe,,,,, but you probably should upgrade the panel and wiring anyway. If a solar system is that marginal on battery or inverters, upgrade it first.

You aren't the only one.

I think DC powered a/c makes sense in a couple situations:
- just starting out with solar.. you can start with just the AC and panels
- If your battery bank is not large enough to maintain your existing loads and the additional AC
- if you are at some kind of limit on system size, and want to continue adding panels/reducing loads (ie, here.. we're limited to 10kw grid tied systems unless we carry a million dollars in liability insurance. so if I was at 9 or 10k... I could legally add more panels *not tied to the grid* to help cool the house..

I'm sure there are a few other edge cases.. but for the most part, I don't see the appeal in plugging panels directly into an appliance, and letting all that potential harvested energy go to waste when the appliance isn't running.

 

[Bob in Tucson]

@watchdoc, even at 10 SEER, it would take a very long time to return your investment on a new mini-split. So, from the financial side, it doesn't make sense to replace the existing unit.

But I'll assume it's not all about money. You're renovating, so if the thought of having to swap units a few years down the road makes you groan, then I say just do it and be done. Hopefully, you won't have to think about it again for a decade and you'll get the benefit of increased efficiency and new control options.

 

[watchdoc]

@watchdoc, even at 10 SEER, it would take a very long time to return your investment on a new mini-split. So, from the financial side, it doesn't make sense to replace the existing unit.

But I'll assume it's not all about money. You're renovating, so if the thought of having to swap units a few years down the road makes you groan, then I say just do it and be done. Hopefully, you won't have to think about it again for a decade and you'll get the benefit of increased efficiency and new control options.

You are correct, it's definitely not all about the money and while I'm doing other renovations, I'm considering this upgrade too since the walls will be open.

 

[ungrounded]

You are correct, it's definitely not all about the money and while I'm doing other renovations, I'm considering this upgrade too since the walls will be open.

That's when you w!n to do it. When the walls are opened.

 

[rustythorn]

I noticed a heating COP of 3.69 listed on the Hotspot and for the Pioneer it is 3.23. Somebody is fudging numbers as HSPF for the Hotspot is 9.6 and the Pioneer is 10. If you multiply HSPF times 0.293, you will see the Hotspot is 2.8 for heating COP and the Pioneer is 2.9

the number change could be a result of the new SEER2 measurements, all of the measurements will change, COP, HSPF, etc... but they might not add a '2' to the end of these other values

 

[Zwy]

the number change could be a result of the new SEER2 measurements, all of the measurements will change, COP, HSPF, etc... but they might not add a '2' to the end of these other values

Both list a SEER2 but I did not use that for calculation. HSPF is what should be used for heating. Unless there is some new formula I'm not aware of.

 

[SoakedUp]

I have one of the best case scenarios for a solar powered mini split. I have a shipping container out in the desert of Southern California. daytime temps in the summer can reach 120°F. During the summer, I usually bring home my small 400 amp hour 12 V battery that powers my small solar set up during the winter. I still have a lot of sensitive stuff inside the container that would benefit from air conditioning and and help it not bake during the day. I’m not sure this mini split will keep the container down to safe or acceptable battery temps (70-80F) since it’s not insulated. But it might keep it under 100F instead of 130F. So being able to use my existing 2 kW of solar panels on top of the container to power a small mini split to keep temperatures reasonable inside the container would be beneficial. I typically don’t need air conditioning nine months out of the year during the on season when I’m out there, so building a system big enough to power the ac for 3 summer months seems a bit pointless. My solar PV and battery bank is already oversized for my uses when I’m at the property.

These units are definitely limited in their uses, but they are clutch when you find that niche.

 

[Sundog33]

No one seems to consider cost when talking about an AC/DC Mini Split.
If you buy the EG4 for around $1200 and dedicated panels for around $1200 your done. Plug it in to AC for balance. End of story.

If you go with running it thru a Solar setup your talking twice as many Solar Panels, large expensive inverter/charge controller and $Batteries,
$Batteries, $Batteries... If you like spending 10 to 15 Grand and then kidding yourself that your getting free energy go for it.

AC is the biggest Power sucker. I personally would go for the Hybrid Mini-Split and keep it seperate from your other shop power needs that can be built with a smaller Solar setup.

 

[sunsurfer]

I would wait till the price drops a bit more for a hybrid. Its a good concept and will be more common going forward.

 

[Zwy]

No one seems to consider cost when talking about an AC/DC Mini Split.
If you buy the EG4 for around $1200 and dedicated panels for around $1200 your done. Plug it in to AC for balance. End of story.

If you go with running it thru a Solar setup your talking twice as many Solar Panels, large expensive inverter/charge controller and $Batteries,
$Batteries, $Batteries... If you like spending 10 to 15 Grand and then kidding yourself that your getting free energy go for it.

AC is the biggest Power sucker. I personally would go for the Hybrid Mini-Split and keep it seperate from your other shop power needs that can be built with a smaller Solar setup.

I have more generated power right now than I can use with long days and good sun during summer. My battery is based upon what is needed for winter use, not summer.

These AC powered inverter mini splits just sip power. Dedicating solar panels just for the purpose of running a mini split doesn't make any sense in my case.

 

[SolarScott]

I have more generated power right now than I can use with long days and good sun during summer. My battery is based upon what is needed for winter use, not summer.

These AC powered inverter mini splits just sip power. Dedicating solar panels just for the purpose of running a mini split doesn't make any sense in my case.

My seven used sharp panels cost $45 each........now I am contemplating setting some up just to run water heaters......

 

[Zwy]

My seven used sharp panels cost $45 each........now I am contemplating setting some up just to run water heaters......

The panels to run my AC powered mini split cost me nothing. I already owned them to run the rest of my house.

I might add an electric hot water heater powered by my free panels as a dump load for excess PV. After all, those panels are free because I already own them for powering my house.

I guess I saved $315 plus the mount.

 

[DrZ123]

Would be nice if EG4 had an auto switch for when the AC is off, the solar panels can contribute to battery charge.

I get the idea of panels just for the AC, especially in certain situations. But if you already have a solar array and batteries, inverter, etc, seems more logical to just add more solar to your system and power the split unit through your inverter

 

[740GLE]

See that’s the thing, proper mini split load should never spike except for the hottest days, it should be running 24/7 at minimal load.

So for an off grid set up with no grid connection you have 1200watts of PV and the unit is only needing 400w you are leaving watts on the table. I’d much rather have that large array go into batteries and then ride the batteries over night.

If I were to add another mini split to my
Grid connected House (no PV set up), as an accessory mini split, yeah sure I’d love to have an isolated system feeding just the mini split.

 

[SolarScott]

See that’s the thing, proper mini split load should never spike except for the hottest days, it should be running 24/7 at minimal load.

So for an off grid set up with no grid connection you have 1200watts of PV and the unit is only needing 400w you are leaving watts on the table. I’d much rather have that large array go into batteries and then ride the batteries over night.

If I were to add another mini split to my
Grid connected House (no PV set up), as an accessory mini split, yeah sure I’d love to have an isolated system feeding just the mini split.

I don't know how hot it gets where you live but mine runs 1500 watts most of the time it is on........But I do live where it is hotter than hell

 

[740GLE]

Northeast, so far from crazy hot.

Peaks around 95, occasionally a day or two above 100 in the afternoon. Inside never gets much above 80 during the peak of the day, with the rooms that have the heads stay closer to 68.

The worsts we get is the overnight outside temps not dropping under 80, but yeah that’s pretty rare.

A house that’s built to keep heat in also does a decent job at keeping it cool as well. Ours was built in 2002 and is pretty decent air tight.

In the evenings our minisplits ramp down to almost idle.

 

[Sundog33]

Also, there is a 30% Government Rebate for Heat Pump/Mini-Splits this year on your Taxes. You can combine the cost of the Panels/Wiring, etc... into the Mini-Split becaise they are dedicated to it. Put out say 3k get $900 back. With that new number in 4 years it will be paid off in savings and you will be putting money right into your Pocket.

 

[ksmithaz1]

The panels to run my AC powered mini split cost me nothing. I already owned them to run the rest of my house.

I might add an electric hot water heater powered by my free panels as a dump load for excess PV. After all, those panels are free because I already own them for powering my house.

I guess I saved $315 plus the mount.

To this point. Once you 'dedicate' panels to a single function, whatever real estate you have available for panels is now consumed for one and only one purpose. I for one think it is not the best use of solar production. If you feed all your solar output to an AIO with batteries, now you can distribute it as you see fit, so this spring when it's 70 outside and the windows are open, the solar can power your refrigerator, or TV, or ... instead of being thrown away. This is also where batteries start to make a play. What percentage of the Solar output are you actually going to use if it is dedicated to a the single function of HVAC? For example, here in Phoenix, my HVAC has been running pretty much non-stop since May. Even at that, other than July/August it's average cycle time might average 60% during the day in May,June,Sept,Oct. Nov-Apr it's going to be closer to 20% or lower, but a little higher at night in Jan when it does get a little chilly from time to time.

Further, even during the middle of the day solar output varies, this was from 6 strings yesterday in Phoenix, on a 'mostly sunny' day:

So every time you dip below the threshold your AC/DC unit is going to have to draw grid A/C to keep it going.

I'm guessing you could hook the same panels, to an AIO dedicated to a normal A/C mini-split HVAC, with a modest battery capability, and see a payback within two years over an ac/dc HVAC with just panels, and have the added benefit of diverting excess A/C for other use. You could do something with a battery bank and an MPPT but now you are starting to get in the weeds. IMNSHO, an AC/DC HVAC system is a pretty special purpose use case: "All I'll ever want to do is lower my HVAC costs with some solar input and I have to replace my unit anyway."

The last think I might mention: If you are producing enough solar with an AIO and batteries to run the HVAC system for an extended period of time, and it cools/heats the space sufficiently, do you really give a crap about the SEER rating? My rooftop package unit is unfortunately new. It is 14 SEER. It works OK. I'd rather have mini-splits. I can't justify replacing it, my money would be better spent on more batteries. If/when it dies again, I will have mini-splits, until then I produce so much power in the middle of the day when I need it it's simply not relevant!

Your needs may be different.

 

[Sundog33]

To this point. Once you 'dedicate' panels to a single function, whatever real estate you have available for panels is now consumed for one and only one purpose. I for one think it is not the best use of solar production. If you feed all your solar output to an AIO with batteries, now you can distribute it as you see fit, so this spring when it's 70 outside and the windows are open, the solar can power your refrigerator, or TV, or ... instead of being thrown away. This is also where batteries start to make a play. What percentage of the Solar output are you actually going to use if it is dedicated to a the single function of HVAC? For example, here in Phoenix, my HVAC has been running pretty much non-stop since May. Even at that, other than July/August it's average cycle time might average 60% during the day in May,June,Sept,Oct. Nov-Apr it's going to be closer to 20% or lower, but a little higher at night in Jan when it does get a little chilly from time to time.

Further, even during the middle of the day solar output varies, this was from 6 strings yesterday in Phoenix, on a 'mostly sunny' day:
View attachment 165854
So every time you dip below the threshold your AC/DC unit is going to have to draw grid A/C to keep it going.

I'm guessing you could hook the same panels, to an AIO dedicated to a normal A/C mini-split HVAC, with a modest battery capability, and see a payback within two years over an ac/dc HVAC with just panels, and have the added benefit of diverting excess A/C for other use. You could do something with a battery bank and an MPPT but now you are starting to get in the weeds. IMNSHO, an AC/DC HVAC system is a pretty special purpose use case: "All I'll ever want to do is lower my HVAC costs with some solar input and I have to replace my unit anyway."

The last think I might mention: If you are producing enough solar with an AIO and batteries to run the HVAC system for an extended period of time, and it cools/heats the space sufficiently, do you really give a crap about the SEER rating? My rooftop package unit is unfortunately new. It is 14 SEER. It works OK. I'd rather have mini-splits. I can't justify replacing it, my money would be better spent on more batteries. If/when it dies again, I will have mini-splits, until then I produce so much power in the middle of the day when I need it it's simply not relevant!

Your needs may be different.

What I can say is my August bill is $295 just for electric Use and Delivery charges - typical for summer months.
The rest of the time its only like $50 bucks, maybe a little spike for Christmas lights... so AC is the number one draw in my home.
So dedicating Panels to the number one power sucker makes sense to me. Why would I spend another 5 to 10k to upgrade my Batterys, Panels and Charge Converter/Inverter for just $50 bucks worth of power per month. That payoff would be 16.6 years down the road.

So if we averaged saving say $200 x 4 summer months, Payed $3000 for the system, Got $900 back on the taxes. -
That's $2100 COP divided by $800 savings a year = payoff in 2.625 years.
That's not to mention any heat savings I would incur in winter. Gas here is cheap compared to electric and I usually run a gas fireplace for 75% of my heating needs so I would need some real time usage to figure that out.

I hopefully wont be pulling ANY power from the grid because the AC Part will be plugged into my smaller Solar Battery System when my Solar output varies. Its just enough to do that, but not enough to run the whole Mini-Split and expect Battery charging at the same time.

I have no issue with using a Mini-Split thru an already existing large Solar infrastructure.
And I see the draw... its very addicting and you just want more.
I am just trying to make a case to "Haters" who say there is no place for a dedicated Solar Panel driven Mini-Split.
- For those reading this in research, this is a cheap, quick payout and easy way to get into Solar,
- For those with small to medium sized systems this maybe a way to up your game without having to redo the system you already have.
- For those who have gone whole hog on Solar, more is better isn't it. : ) Get the AC/DC one and sleep better at night knowing if your system blows up you can just plug your panels directly into the Mini-Split.

Different strokes for different folks, doesn't make it right or wrong. But in terms of cost I think the AC/DC is a winner.