Chinese 48V DC mini-split air conditioning - any thoughts?

[davelondon]

I'd like to install a 48V DC air conditioning system.

The Hotspot Energy system sounds great, but it's very expensive at $2,000 USD, and Hotspot can't organise the shipping (I'm in the UK) so I'll have to get a shipping company to pick it up from their warehouse and organise all the export / import paperwork. This will probably be very expensive. Here's some chat about the Hotspot system.

Recently I've found a similar solution from a Chinese manufacturer that's being resold by various Alibaba merchants. I'm not 100% sure who the original manufacturer is, but I've been speaking to Candice Tian at Supergreen Tech (www.supergreensolar.com / www.solar-air-conditioner.com) who seems to be very knowledgable about the systems. Here's their product page. (Here's another alibaba merchant selling the same device).

Candice quoted me $418 for the aircon unit, plus $780 for door-to-door shipping to the UK, including import tax.

Has anyone had experience with these units?

 

[Quattrohead]

I would be very concerned about being the guinea pig for some random new supplier.
Why don't you source a regular mini split that would be easily available in the UK along with your typical inverter etc to run it, I think you'd end up at about the same price with far less risk.

 

[davelondon]

Yes that's the other option, but it ends up being much more expensive with the inverter... Also the inverter will probably be pretty noisy, and will be inside the room, so not ideal...

 

[DJSmiley]

What about an all-in-one?

Assuming you don't need backfeeding to the grid, eg a Growatt SPF 5000 seems to be a nice unit matching your requirements.

1000 GBP (approx) for the aircon, and 700 for the solar controllers...

A Growatt all-in-one (Approx 1000 GBP) and a Daikin AC is about the same price... And Daikin is generally considered not to be the cheapest no-name stuff. Also usually pretty silent, which is also a benefit over some cheap units. (both inside and outside - your neighbours will thank you).

Just an example:

Growatt SPF 5000ES off grid

De Growatt SPF 5000ES een mooie oplossing voor een off grid systeem!

www.stralendgroen.nl

Daikin Sensira 9000 Btu/2.5 kW R32 - COOL&HEAT - WiFi / FTXQ25A/RXQ25A - Aircoplaza Zwolle

aircoplazazwolle.nl

I personally won't spend 1000 GBP on an unknown Chinese aircon unit. At 48V, there are quite high currents, so your wiring needs to be sufficient, especially on long runs. I don't see much information (is it actually an inverter aircon, or just an on/off unit)

I think their ratings are also suspicious.. a 9000 BTU unit (2600W cooling) takes only 450 watt input? That's a COP of almost 6... Sounds too good to be true. Even higher when in heating mode?


If you go for a cheaper brand AC, you will end up cheaper.

 

[chrisski]

My concern with a 48 VDC air conditioner is the amount of amperage it may use and the wiring for it. I can’t tell from the spec sheet the amount of amperage used, but I guess between 30 and 60 amps for the 18 K BTU unit. That would be some thick wiring if run longer distances.


18 k BTU is the minimum size I would want for my 35’ RV, although the smallest unit says the 9k BTU will work, but my 15 k BTU won’t work once its in the 100s.

The picture of the solar panels is pretty misleading. Panels those size are a battery assist at best. At about 180 watt per meter squared at full production, you’d want 10 meter squared at least, and looks as if that is only a meter squared of panels. The panels do run inside which tells me the AC is hard wired to a 48 volt system.

 

[DJSmiley]

With approx 6000W and an EER of 6, power would be something like 1000W for the 18kBTU unit. which is like 20A. Thats managable.

However, if the wires are over a few feet you need to upscale pretty fast, especially if there is an inrush current, which is going to be expensive (long / thick copper wires)...

But in reality, that efficiency is not all the way, so either the current require goes up significantly, or the output power is much lower than stated.

 

[davelondon]

They mention 750W (so 15A) as the max load for the 12,000 BTU version, which is what we were planning. The room is well insulated so should need more than that.

Also the all the equipment will be right next to each other, so cable runs won't be long.

However, if we extend the system and add another aircon unit in the main house, it'll need a ~30m cable run.

For a 3% cable loss at 15A over 30m, we only need 16mm2 / AWG 5, so I don't think that's a big concern? Of course 240V would be more ideal for a long cable run like that...

 

[davelondon]

What about an all-in-one?

Assuming you don't need backfeeding to the grid, eg a Growatt SPF 5000 seems to be a nice unit matching your requirements.

1000 GBP (approx) for the aircon, and 700 for the solar controllers...

A Growatt all-in-one (Approx 1000 GBP) and a Daikin AC is about the same price... And Daikin is generally considered not to be the cheapest no-name stuff. Also usually pretty silent, which is also a benefit over some cheap units. (both inside and outside - your neighbours will thank you).

Just an example:

Growatt SPF 5000ES off grid

De Growatt SPF 5000ES een mooie oplossing voor een off grid systeem!

www.stralendgroen.nl

Daikin Sensira 9000 Btu/2.5 kW R32 - COOL&HEAT - WiFi / FTXQ25A/RXQ25A - Aircoplaza Zwolle

aircoplazazwolle.nl

I personally won't spend 1000 GBP on an unknown Chinese aircon unit. At 48V, there are quite high currents, so your wiring needs to be sufficient, especially on long runs. I don't see much information (is it actually an inverter aircon, or just an on/off unit)

I think their ratings are also suspicious.. a 9000 BTU unit (2600W cooling) takes only 450 watt input? That's a COP of almost 6... Sounds too good to be true. Even higher when in heating mode?


If you go for a cheaper brand AC, you will end up cheaper.

This looks good, although I don't see that Growatt being sold in the UK anywhere... Any idea why?

 

[DJSmiley]

30m of 16mm2 is expensive.. its like 300 GBP...

Not a concern to run 16mm2, but it's expensive and thick wire (ugly / harder to run through an conduit)

Growatt in the UK... I don't know if or why. Not too familiar with the UK market tbh.

 

[chrisski]

They mention 750W (so 15A) as the max load for the 12,000 BTU version, which is what we were planning. The room is well insulated so should need more than that

I don’t know mini spits all that great, but I’d expect closer to 1 kw when it’s working hard, cycling down as the place cooks off.

I find getting info difficult. There’s a post or two that talk about draw average and beginning on a mini split, but hard to find that data.

This seems to be getting into the too good to be true. If you do decide to do this, I’d like to see a post, and I may follow you. I won’t blaze new trails, but I’ll be a follower.

 

[davelondon]

A Growatt all-in-one (Approx 1000 GBP) and a Daikin AC is about the same price... And Daikin is generally considered not to be the cheapest no-name stuff. Also usually pretty silent, which is also a benefit over some cheap units. (both inside and outside - your neighbours will thank you).

The Growatt systems look good... it's just frustrating you can't scale the MPPT side of things without adding a whole new inverter. My roof layout means I have either 11 or 13 panels, so I'll need two MPPT controllers to get the best out of that. Then there's a shed next to the studio, which is angled in a different way, so if we extend the system to that roof too it'll need another MPPT.

 

[kkz2dgz]

Dave,
Been doing research on the same situation for a custom 22ft travel trailer dont want to fire up inverter to run ac and burn 100 watts an hour to invert dc to ac with limited space for batteries, From what I understand alot of stuff comes from china ....you just have to do your research and look at company reviews......Im looking at the same pure 48vdc minis no inverter .........let me know what you ended up doing curious.....

 

[davelondon]

For my dad’s studio we cancelled the solar idea and just installed a mains powered aircon unit.

 

[BenQ]

If you ever think of this again, should something like this have worked?

DC Solar Heat Pump | Solar Powered Heating | Solar Cooling

 

[BenQ]

Or this

 

[davelondon]

BTW I’m in the UK.

Hotspot unit looks great and it’s what I’m planning on using in my expedition vehicle build… however they won’t ship to the UK and getting a freight forwarder to collect from Hotspot in the US and manage the import will be very expensive. Far too expensive for my dad’s studio.

EG4 unit looks great but USA voltage only.

 

[BenQ]

BTW I’m in the UK.

Hotspot unit looks great and it’s what I’m planning on using in my expedition vehicle build… however they won’t ship to the UK and getting a freight forwarder to collect from Hotspot in the US and manage the import will be very expensive. Far too expensive for my dad’s studio.

EG4 unit looks great but USA voltage only.

Ah, so the 120v ac won’t work, but I think they have this one which is 240v ac will that work? It’s more expensive though…https://signaturesolar.com/eg4-hybrid-ac-dc-solar-air-conditioner-2-ton/

 

[davelondon]

Aaah interesting... But as you say it's $2,000, which is more than three times the price of the unit we bought (£471 = $566).

Also... I assume this is designed for USA split phase 240V... I'm not sure I'd want to connect this to single phase European 240V... Perhaps in theory it would work, but I'm sure the manufacturer wouldn't recommend it, and I'm sure it would void the warranty.

 

[BenQ]

Yeah, I know EG4 used to sell the Growatt inverter that only put out 240 single phase, so maybe they would know if their heat pump would work on that. Unfortunately, the cost seems to be a bigger issue.

 

[TorC]

For a 240V only device, AIUI, 240VAC RMS is 240VAC RMS, and the only difference is in the US, each leg is referenced 120V relative to ground, while in the UK one leg is referenced to ground. The US device requires isolation on both legs, rather than theoretically just one on the UK device, so on this count, I'd be surprised if there's an issue.

HOWEVER, there's the pesky 60Hz/50Hz issue, and I would not want to install something like that without ensuring the motor and the rest of the system are ready to handle it. Possible, but not guaranteed. Unfortunately, the compressor/motor are probably a single unit, so you'd probably need a refrigeration tech to retest and recharge the system after replacing it.