Why hybrid solar air conditioners but not the 48vdc ones?

[jameshowison]

Anyone have any idea why Signature Solar sells the hybrid "solar" air conditioners (which directly connect panels via MC4 connectors) rather than the straight 48vdc ones?

They sell this one https://signaturesolar.com/eg4-hybrid-ac-dc-solar-air-conditioner-1-ton/ but it uses grid power when the panels aren't producing. Can't be connected to a battery (well, unless via an inverter which seems very roundabout)

Looks like Sig Solar sells this one from Deye:

Hybrid ACDC 12K/18K/24K | Solar Air Conditioner

Deye hybrid ACDC solar air conditioner, DC48V solar air conditioner. 100% saving energy, easy installation.

deyesolar.com

But Deye also make a straight 48vdc one designed to connect to systems with batteries (that is very similar to the Hotspot 48vdc heat pump). This would work fine with the All-in-ones (although they show a separate MPPT).

DC48V-09K/12K/18K/24K | Solar Air Conditioner

Deye hybrid ACDC solar air conditioner, DC48V solar air conditioner. 100% saving energy, easy installation.

deyesolar.com

That one is actually mentioned on the manual on SigSolar's site (see p 8): https://signaturesolar.com/content/documents/EG4/EG4 Mini Split Manual-12000-24000 1.0.0.pdf

I can't find a US distributor for those at all, although there might be some on alibaba.

 

[robby]

Anyone have any idea why Signature Solar sells the hybrid "solar" air conditioners (which directly connect panels via MC4 connectors) rather than the straight 48vdc ones?

I would suspect it's because they are Inverter based heat pumps so they actually work on High Voltage DC to run the compressor.
It's a lot easier to work with 100V-300V of DC than to try and step up 48VDC to a higher value. The AC is just rectified to DC so it's already high voltage.

 

[jameshowison]

I would suspect it's because they are Inverter based heat pumps so they actually work on High Voltage DC to run the compressor.
It's a lot easier to work with 100V-300V of DC than to try and step up 48VDC to a higher value. The AC is just rectified to DC so it's already high voltage.

Right, that is useful to know.

Yeah, that would make them more efficient (at least direct from DC), but the hybrid ones (direct 100v-300v) just don't seem to fit a model that I understand.

Maybe I'm missing something, but to use solar with them seems like you have to have panels dedicated just to them. And then you have to use your inverter to supply them overnight (or on cloudy days, or when those dedicated panels get shaded). Or I suppose you could just route everything through the AC route and your inverter ... but then why both with the solar aspect at all?

Any guidance on how one can think about the relative efficiency of these pathways:

Panels --> Inverter --> AC 120v --> rectifier --> Air conditioner inverter

vs

Panels --> SCC --> 48vdc --> step up electronics --> Air conditioner inverter

vs

Panels --> [ internal MPPT? ] --> Air conditioner inverter.


--J

 

[AJB]

I believe there will be another source for Deye‘s units opening shortly, and if they carry all the main office does the 48v should be in their lineup.
I have one of Deye’s 24k units and plan on getting a few more.
I’m on grid and grid tied solar is too regulated for me (permits, inspections and everyone wants $$). For me panels are cheap, last purchase from Santan was at 13¢/watt so a dedicated array wasn't bad and I didn’t have to dance with the authorities. Yes I may need need the grid after hours and on my few cloudy days and I’m ok with that.

 

[RCinFLA]

The electrical part is basically the same as a HF All-In-One inverter, except the AC PWM output stage is a three-phase inverter to drive the variable speed compressor.

PV charge controller is a boost converter to take panel array up to about 380-400 vdc which is the voltage the three-phase inverter runs from. The PV charge controller will have less conversion loss from PV array when PV array voltage is at the higher end of allowable PV input voltage range. The greater the PV array input voltage, the less boost conversion with lower current, is required giving better PV controller conversion efficiency.

One question is the 230vac input to 380 vdc supply a simple rectifier-filter or does it have power factor correcting AC-DC power supply. European regulations on power factor for AC loads at that level of power require a power factor correcting AC-DC power supply for mini-split air conditioners.

From a pure PV power point of view, this arrangement will give better PV conversion efficiency than a 48vdc input would yield. But for 230vac supply input you want a power factor correcting power supply to run from a battery powered 230vac AC inverter or a generator, otherwise it will result in more battery powered AC inverter / generator losses.

 

[eXodus]

230vac input to 380 vdc supply

Pretty simple, just have a step up transformer and then rectify. That's the beauty about AC just changing voltage is super easy. Takes a solid hunk of copper and metal but is cheap.

At least my mini split has a transformer not sure what is does or which voltage but it's there.

 

[Deadeyecustoms]

Anyone have any idea why Signature Solar sells the hybrid "solar" air conditioners (which directly connect panels via MC4 connectors) rather than the straight 48vdc ones?

They sell this one https://signaturesolar.com/eg4-hybrid-ac-dc-solar-air-conditioner-1-ton/ but it uses grid power when the panels aren't producing. Can't be connected to a battery (well, unless via an inverter which seems very roundabout)

Looks like Sig Solar sells this one from Deye:

Hybrid ACDC 12K/18K/24K | Solar Air Conditioner

Deye hybrid ACDC solar air conditioner, DC48V solar air conditioner. 100% saving energy, easy installation.

deyesolar.com

But Deye also make a straight 48vdc one designed to connect to systems with batteries (that is very similar to the Hotspot 48vdc heat pump). This would work fine with the All-in-ones (although they show a separate MPPT).

DC48V-09K/12K/18K/24K | Solar Air Conditioner

Deye hybrid ACDC solar air conditioner, DC48V solar air conditioner. 100% saving energy, easy installation.

deyesolar.com

That one is actually mentioned on the manual on SigSolar's site (see p 8): https://signaturesolar.com/content/documents/EG4/EG4 Mini Split Manual-12000-24000 1.0.0.pdf

I can't find a US distributor for those at all, although there might be some on alibaba.

Look at www.zamnaclimate.com they sell complete off grid native DC air conditioners that are able to run solely off your solar panels, no batteries or grid required. You can also run off batteries & they also sell the hybrid systems. I bought the 12k btu off grid but haven't had the chance to install it yet. They say 6 panels can run the unit directly through solar energy & with battery bank can run 24/7. EER 19 rating, pretty sweet system I found from a youtube video last year. I have a 28kwh 13k watt 48v solar system being installed for my new shop/studio.

 

[timselectric]

I installed a Hotspot 48v mini split last weekend.
It works great. And super efficient.
But expensive.
$2.3k

 

[eXodus]

I installed a Hotspot 48v mini split last weekend.
It works great. And super efficient.
But expensive.
$3k

where did you buy it?

 

[timselectric]

where did you buy it?

Edited price to $2.3k in previous post.
Engineer77

DC Air Conditioner for Off Grid Use - Practical Preppers

Cool or heat your space completely off the grid! The HotSpot DC48 is the perfect air conditioning unit for your DC power source. For off grid applications only.

practicalpreppers.com

 

[Plum Crazy Rob]

Zamna is obviously dealing the www.hotspotenergy.com units BTW...

 

[Eber]

I would add that we should be checking how low temp outside they heat to also, some of those seem to only provide heat down to 15F. That would be bad here in the north.

 

[timselectric]

I won't be able to confirm until next winter. lol

 

[Plum Crazy Rob]

Also, nothing is ever actually 3-phase AC per se in these units correct ?? - but that is used as a colloquial reference since a 3 phase AC motor is analogous to understanding how a brushless DC motor/compressor works, variable rate electrical commutation of DC current to the motor stator windings to enable variable speed control via the main PCB - correct??

 

[eXodus]

Edited price to $2.3k in previous post.
Engineer77

DC Air Conditioner for Off Grid Use - Practical Preppers

Cool or heat your space completely off the grid! The HotSpot DC48 is the perfect air conditioning unit for your DC power source. For off grid applications only.

practicalpreppers.com

I like the COP of over 5 for direct 48V. That is very impressive.

I'm always looking for total cost of ownership.
To run a Minisplit you need at least a 3000W inverter. - Which is about $600-800. In addition to the $1000 Mini split.

Not yet fully price comparative - but getting close. Another advantage I see - it's one less box - you don't need the inverter.
Or when the inverter fails - you still have the heatpump. Which is an advantage in many scenarios.

 

[jameshowison]

Zamna is obviously dealing the www.hotspotenergy.com units BTW...

Sure looks like it. Same specs, lots of the same marketing language. Head unit looks the same. Price very similar. Same discussion of 6v golf cart batteries. Battery type listing doesn't mention lithium ...

Wonder who actually builds these things

Battery specs: $2240 for 16 x Trojan T105 225amp hour. These are 6v batteries, right?

So that's 8 in series just to get to 48v ... then reduce by 50% because they are lead acid. So do I have that right that that is usable capacity of 115 amp hours at 48v or 5.2 KwH. Which is like 43c a wH. Server rack batteries look good, and way simpler, why don't they advertise them that way ... Maybe just old marketing materials?

 

[Plum Crazy Rob]

I ran Hotspot down to a factory in China. Looks like built to order. Toshiba-GMCC compressor. That's all ok to me. Company appears to be US based.

 

[hwy17]

Also, nothing is ever actually 3-phase AC per se in these units correct ?? - but that is used as a colloquial reference since a 3 phase AC motor is analogous to understanding how a brushless DC motor/compressor works, variable rate electrical commutation of DC current to the motor stator windings to enable variable speed control via the main PCB - correct??

As I understand it no, the variable speed compressor motors are bona fide 3 phase AC motors and the inverter achieves variable speed operation by varying the frequency of it's output.

Same concept in VS pool pump motors.

I am open to your understanding being higher level and more accurate than mine. but the board has a 3 wire delta output as far as I can tell.

 

[Zwy]

I installed a Hotspot 48v mini split last weekend.
It works great. And super efficient.
But expensive.
$2.3k

Hope it works out better than the experience here. https://diysolarforum.com/threads/hot-spot-energy-acdc-solar-mini-split-total-failure.63239/

I don't blame the condenser failures on the manufacturer, it is pretty clear the proximity to the ocean would cause the failures.

Energy usage might be another matter.

 

[timselectric]

Hope it works out better than the experience here. https://diysolarforum.com/threads/hot-spot-energy-acdc-solar-mini-split-total-failure.63239/

I don't blame the condenser failures on the manufacturer, it is pretty clear the proximity to the ocean would cause the failures.

Energy usage might be another matter.

I didn't buy the solar mini split.
I bought the 48v unit.
I'm no where near the ocean. (That's where hurricanes happen)
It's drawing 300 to 500 watts, when it's running.

 

[SilverbackMP]

Hope it works out better than the experience here. https://diysolarforum.com/threads/hot-spot-energy-acdc-solar-mini-split-total-failure.63239/

I don't blame the condenser failures on the manufacturer, it is pretty clear the proximity to the ocean would cause the failures.

Energy usage might be another matter.

I am in the land of mini splits in a very small country surrounded by ocean on three sides. A good chunk of the population is by the ocean given that Seoul-Incheon and Busan are the two biggest cities and both are ports.

I noticing more and more Gree and Midea clones here along with Carrier (Midea). LG (followed by Samsung) is still by far the most numerous, but others are creeping in.

The Toshiba compressors were designed by a company that is native to a chain of islands.

I guess my point is, they should be able to withstand it but apparently can’t.

 

[Ampster]

Same concept in VS pool pump motors.

And the same concept as found in most EVs. In that case the advantage is a faily flat torque curve, meaning high torque at low RPMs and no need for a transmission.

 

[Plum Crazy Rob]

Still think the compressors are DC motors, and the variable speed is achieved by varying the frequency of the electronic commutation of DC voltage to the stator coils, which apparently are in fact arranged like 3 phase motors, frequently in multiples of 3 - leading to more assumptions and confusion

Here's the compressor from my minisplit:

 

[Plum Crazy Rob]

And on other subject can ANYTHING electrical/electronic survive that "beach" climate ??

 

[Ampster]

Still think the compressors are DC motors,

I am sure the Panasonic one you listed is a DC motor. I am also positive my LG is an AC inverter driven motor. I also know my refigerators are also inverter driven AC motors.