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Author Topic: Solar Split System Inverter Air Conditioners  (Read 1209 times)

old seagull man

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Solar Split System Inverter Air Conditioners
« on: July 24, 2019, 05:07:24 AM »
Have seen a few adds for these lately and wondered if anyone had any practical experience with them, or of them.
I have lots of panels, so powering one wouldn't be very difficult.

Solar Split System Inverter Air Conditioners

Here is the sales pitch;


HYBRID Solar AC units are as the name suggests. They run directly off solar panels during daylight hours or when their is sufficient sunlight and mains power in the evening or at times of limited sunlight. They can also run on a combination of solar and mains power.

Ideal applications include Businesses, Schools, Offices, Site Camps or wherever heating or cooling is required during the days they run for free when there is sufficient daylight.

STAND ALONE 48 volt 100% Off Grid units run completely off solar panels and charge a battery bank for use during the evening or at times of little sunlight.

Perfect for any off grid application such as remote communities, Islands, farms, mining sites or off grid residential use.

Solar AC, both Hybrid and Stand Alone is Proven Technology with hundreds already installed in Australian Telco towers to cool equipment and batteries.



So you know all i know about them now.




BruceM

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Re: Solar Split System Inverter Air Conditioners
« Reply #1 on: July 24, 2019, 05:32:33 AM »
I've done an EMF mitigation survey on two (on grid) homes in the last few months with regular inverter type split systems.  I got inside them and also studied the limited schematics and such I could find on line for them (two different manufacturers). They are audibly fairly quiet and owners report good economy.  It makes sense that someone has added a PV input circuit to them, as it would take only a DC to DC boost circuit and adding the PV input connectors to do so.  The inverter part of these is a variable 3 phase motor drive for the exterior compressor.

 Alas, they have not been designed with any concern for EMI on home wiring, and they do have pretty nasty conducted EMI that affects the whole home wiring.  The interior units have their own switching supply and use DC PWM on the fan motor.  Even when "off" the interior units affect a half the AM band (and higher) frequencies.   It's really a pity as with a simpler design, using two speed induction motors both inside and out, you could have similar functionality without all those expensive failure prone electronics, and no home power EMI at all.  Alas, we seem doomed to products which always use the latest technology...like refrigerators and washers and dryers with embedded microcontrollers, switching power supplies, and digital readouts.  I'm sure by now there are digital f*ing  toasters and crock pots too.





« Last Edit: July 24, 2019, 05:36:25 AM by BruceM »

AdeV

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Re: Solar Split System Inverter Air Conditioners
« Reply #2 on: July 24, 2019, 09:59:28 PM »
Unfortunately for EMI-sensitives, switching power supplies are highly efficient and physically very small, compared to the old transformer-rectifier-capacitor units. I have old 1980s computers which have transformers weighing over 4lbs/2kg, capacitors the size of a coffee mug and honkin' big diodes just to provide a few dozen watts at +/-12v and 5dc... whereas a switching capacitor of similar capacity will fit inside the footprint of just one of those big ole caps. The tradeoff, of course, is bucketloads of noise, which for most of us isn't a problem (yet, at least).

Rather than trying to silence the AC unit at the electrical level, is there no way you can shield it sufficiently to fix the EMI issues?
Cheers!
Ade.
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0x Lister JP4 :( - Sold to go in a canal boat.

veggie

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Re: Solar Split System Inverter Air Conditioners
« Reply #3 on: July 24, 2019, 10:36:23 PM »
Old Seagull,

Sounds like an interesting product.
Can you post some links to where you were looking at these units

cheers,
veggie
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BruceM

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Re: Solar Split System Inverter Air Conditioners
« Reply #4 on: July 24, 2019, 10:47:39 PM »
The independent research shows that brain function (Dr. Andrew Marino and others) is measureably affected in people with no awareness of pain or other sensations from EMF exposure. It just ultimately manifests as a variety of illnesses unique to that individual.  I'm pretty biased, because for over 25 years, EMI immediately hurt and was profoundly mentally disturbing, though now I have no immediate sensation at all on good days, though it does affect my autoimmune diseases later. 

Tremendous improvement of emissions can be done at minimal cost when addressed early in the design phase.  Texas Instruments makes motor speed control IC's for example, which intentionally slow switching times for reduced emissions.  Likewise Linear Technology offers reduced EMI switching controller ICs that also use slower switching times to minimize EMI at the source. Choice of transistors, diodes, inductors and even basic circuits topology choice all play a big role. Toroidal inductors wound for minimal stray field are good, and shielded pot cores can also be a big help.  Carefully tuning snubbers around diodes and switching elements also has a big payoff for peanuts.   The last and most costly solution is to throw passive filtration and shielding at the problem you should have solved by design,  but that can be effective too, though to shield a bad design to a high degree is very, very expensive.  Thus the preaching of EMC specialists to solve the problem in design phase.

Switchers in the hands of a poor designer are a debacle, for EMI. In the hands of a skilled designer with lots of EMC experience, they can be pretty decent.  Sadly, right now, no one is paying attention.  Also, good designers are often hand tied by cost pressures.

Toroidal transformers for linear supplies are one simple solution with good efficiency and more compact size and weight. Alas, they are quite expensive due to the difficulty in winding them. 

Alas, there's no competing with high frequency switchers for compactness, light weight, and low cost.  Except when you consider your family's health.  Our public health statistics are not looking good in many areas.


glort

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Re: Solar Split System Inverter Air Conditioners
« Reply #5 on: July 24, 2019, 11:28:25 PM »

Seems to me the advantages of these Air cons are very limited.
The ONLY upside I can see is if you are restricted in the amount of solar you are allowed to have grid connected, you could run one of these  and -MAYBE- get past the restrictions depending what they specifically are.

Here I'm pretty sure if there are panels and a mains connection, it's counted in your allowance. Might be a way for people to sneak through some extra KW but most people whom are all worried about rules and regulations designed to screw them over won't  touch them without the approval of their power masters.

For everything else, despite looking at these a while back, I was unable to determine what the advantage was?  If you are on grid then I would pretty much guarantee that buying the same amount of panels and a standard inverter AC is going to be cheaper.  If you are off grid, same would apply. Add the panels for the extra power to run not only the AC but charge your batteries and run other appliances as well.  Maybe you would need a larger or an extra inverter for a std system? Seem to me that would be money better spent whee you could use it every day rather than just 3 months a year on average.

Are these things Reverse Cycle? I couldn't see any mention of that. If they are I would find the solar component very limited in it's contribution in winter  and if they are not, you are going to have 4? panels sitting there most of the year doing nothing when if they were hooked into the main system of the house they could be contributing to the home loads and saving money or doing battery charging.

As for the 48V version I saw, Meh. Can do that with an inverter or a VFD which is probably what they have built in. anyone with an off grid system of 48V would have inverters anyway bar maybe a very limited few.

Unless these things are all sales Hype, I must be missing the USP here. What I did find showed they were MUCH more exy than a standard split of the same ( small) size.  I noticed some Complete and utter hype about them being more efficient like they had invented a new technology but of course they are using the same setup all modern AC's use.

What is the advantage with these things to justify their greater cost??

veggie

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Re: Solar Split System Inverter Air Conditioners
« Reply #6 on: July 25, 2019, 02:48:28 PM »
Hey guys,

I would love to use alternative power to cool in the summer.
There is NO WAY that my Roid could power my home central air conditioner.
The only way I could use my roid to help in hot weather is to get a smaller air conditioning unit and run it in a single room such as the bedroom to aid sleeping. Or charge a battery bank with the roid and draw from it in the evening to power a small AC unit.
For emergency cases such as weather related power outages in the lower USA for example, would it not be possible to build a small system that could run from a small generator unit. Perhaps even with a battery bank and inverter which could run the system deep into the night (quietly) then recharge the next day.
A great project for those who love to play with generators and batteries and solar panels and switches and....and...and   ;D

A 12 or 24 volt unit designed for vehicles may be a good starting point.
I'm not very familiar with AC units and what is available, but I think low power single room units would be a great use for excess solar power or energy created from waste streams like vegetable oil.

I'm not suggesting this particular product, but lets use this as an example.
https://www.youtube.com/watch?v=jrHVnayveHw
minihvac.com

I'm sure there are many other small units available in various voltages and configurations.
This has me thinking  ::)   Could be a fun project. Not trying to cool a whole house, but lets say a small workshop or a bedroom during a failure of the main AC unit.

Heck ! when not needed in the house I could move it out to the greenhouse and run it there ... from the solar/battery system.
Would have to be small. Say around 4000 btu ( or 1.2 kw ). It's a small greenhouse.
« Last Edit: July 25, 2019, 03:00:01 PM by veggie »
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glort

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Re: Solar Split System Inverter Air Conditioners
« Reply #7 on: July 25, 2019, 05:58:28 PM »

The problem for me with anything battery is COST.  If you don't have/ need batteries because you are on grid, trying to save money goes out the window the second you mention them.

I was playing round with a car AC a couple of years ago and had it running in test setup, hooked up all in one tight unit so it ran but wasn't cooling anything.
A mid size car AC is roughly similar to a mid size household split.   A roid could drive a very useful car AC that would do a room or two depending on the ambient temp.

Car AC is pretty easy, you drive the compressor off the engine and you need a little electrical power, about 200W for the compressor Clutch, the evap fan and the condenser fan.  You could extend the plumbing round a corner a ways so the evap unit was away from the condenser and engine.  Run the copper tube, vac it down then gas it up to the required pressures. as long as you have the pressures right on the high and low side all good. Run a wire for the evap icing sensor back to the compressor clutch and thats pretty much the control side.  Cheap thermostat would replace the car computer that often takes care of that these days. You just set the thermo to sense when the Evap unit is down to 2o generally to stop it Icing up. Once it hits that the compressor kicks out till it warms up again and that's it.  You would run one for the room temp sensor or just turn the evap fan down low.  Run a PWM controller on the Evap fan and it's done.

Anything from a bout 3-10 Hp would drive a decent car AC pretty well.  I use LPG as the refrigerant which is of course cheap, safe and you only need to run about 50% of R-134a. It works better than 134A IHMO. I know I did the truck with it and it was far colder than it ever was on 134a.  Mrs complained about it not working very well to complaining she was freezing her proverbial off.

I have been thinking about doing this here. I could install it at the far end of the house that gets all the shade and stays cooler and run the evap pipes back up through the roof.  Thing is I make so much solar power in summer that it wouldn't be worth it.  I was going to put an RX valve on my setup but never got that Round  tuit before we moved home.  that would give heat in winter and if the thing was engine driven it would be a ball tearer  Because you could utilise the engine heat back through the evap unit which would make the thing very efficent and give it the ability to work in sub zero temps very effectively.  Instead of very cold air going through the fan coil in winter it would be easy to saturate the coil with 40oC air temp which it would love.
Easy to utilise exhaust gas as well and pull the heat from that.

I am going to refine my water misting system for this summer. I had a couple of garden Micro mist jets aimed at the condenser coil last summer and it made for a BIG difference in cooling effectiveness.  I just hat them running from the tap but this year I'll run the water through a garden watering Solenoid and tap a signal from wither the fans or the compressor so the water only runs when the machine is running. I'll add in a thermo so it only runs when the air temp is over 30-35.  Cool enough at night not to need it.
I may look for a decent pump and use the water from a nearby rain tank. The misters don't use much and what they do use is VERY well worth the benefit of keeping the machine on it's efficiency curve.

veggie

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Re: Solar Split System Inverter Air Conditioners
« Reply #8 on: July 25, 2019, 08:45:40 PM »
Useful info, thanks Glort.
My interest is in trying to make some use from the excess energy capacity that have.
3kw of engine generation from free fuel or WVO. and 2KW of solar.
Cooling a room in the house seems like a really good use for it in summer. Even without batteries.
My transfer switch isolates 8 individual circuits in the house. Meaning I can leave 7 circuits on the grid and switch one over to the Listeroid.
I have been working on silencing the Roid and it's barely noticeable from outside my garage at night and run the engine for 4 - 6hrs.
Then buy a single room air conditioner and plug it into one of the designated Listeroid outlets (120 VAC) at night.
The during day plug the AC unit into a grid outlet .... THEN connect the solar to the house through a cheap grid tie inverter and let the solar offset the power used by the grid powered AC. I think that could all be set up in a nice tidy system.

In the winter (Very cold here in Canada) I could re-purpose the system to make heat. Hot water from the panels. (Once Glort gets our solar PV water heating controller designed )  ;)

Misting:
It's a great method of cooling. Especially for a greenhouse. A string of misting nozzles down the middle ridge of a greenhouse ceiling does a very good job of evaporative cooling. Very efficient too. Only need a small pump (or house pressure).

« Last Edit: July 25, 2019, 08:57:21 PM by veggie »
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - Lease/Neville Alternator
- Kubota Z482 - 4kw
- JiangDong R165 Air cooled - 2 kw

glort

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Re: Solar Split System Inverter Air Conditioners
« Reply #9 on: July 26, 2019, 01:05:58 AM »

So you want to do it electrically only?

With your solar, can you clarify the excess 2KW? Is that power over and above what your system normally generates and pushes back to the grid ( do you get a fit?) or is it 2Kw of spare panels you have sitting round you'd like to use? If the latter, do you have a grid connected " Main" solar System?  Is your power meter electronic and registers back feed or is it the old analogue spiny meter that goes backwards if you are generating more than you use.

I'm thinking if possible, you would be better to use the roid to offset the power used by the AC by going direct back into the mains. This will eliminate the switching and unplugging the AC unit which I think may become Tedious.

-IF- you are fortunate enough to be able to store the power though " credit" in the meter, you could get a bigger AC unit and run the roid longer hours to offset the consumption.  That said and without knowing your power costs and arrangement, I would find it unlikely that running an engine even on free fuel will be cheaper than grid power when you add up the REAL costs and Maintenance.

Our power is exy but for the sake of flawed demonstration, I'll assume you pay .20C Kwh which I think may be on the high side but anyway.
If you run the engine 5 hours and are making 3 Kw, that's 15 Kwh x .20C which is $3 night.  Times by 90 days which would be the main part of summer or co -incide with your billing cycle ( don't you guys have some favourable system where you can bank summer credits against winter draw or something)
so your saving is $270. That's if you ARE paying .20C Kwh and if you run and use the that much power every day which I am doubtful of. Some days will be cool, some you may be out etc.

If we look at the 2 KwH of solar, You should be able to get a x5 factor for that  so 10 Kwh a day generation. That would give you 25Kwh all up.
I run a muther of an AC in 40oC weather here in summer and I can tell you, no way a window mount AC is going to use that much power.
This being the case..... You can either run 2 small units ( or probably just go get a Decent split installed that will heat as well)  or you can probably get away without running the roid.

If you want to run the roid  ( Given you are a perfectly normal man of good constitution and mental balance and who wouldn't want to run their engine for a practical purpose? ) then you also need to take into account the costs of collecting and filtering WVO etc. Now if you are an IMbalanced individual like me, you probably put that down to being fun and enjoyment  but for sensible people.... it does have a cost as does wear and tear on your machine for what I'm thinking might be closer to saving .50C hour.

Anyway, give us some info so we can better understand your situation and setup.


glort

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Re: Solar Split System Inverter Air Conditioners
« Reply #10 on: July 26, 2019, 05:35:37 AM »

 (Once Glort gets our solar PV water heating controller designed )  ;)

Mosfets arrived today.  Bit of luck I'll get the controllers I ordered next week and can start playing.

veggie

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Re: Solar Split System Inverter Air Conditioners
« Reply #11 on: July 26, 2019, 02:48:17 PM »

"Anyway, give us some info so we can better understand your situation and setup."

Ten 220 watt panels on the shelf doing nothing.
One Listeroid and WVO system (3kw max) sitting idle in case of emergency.
I don't want to backfeed the grid. But making cold air in summer seemed like a good use of spare power without backfeeding.
Also have a 12 volt 660 amp battery bank (charged by other panels) un-utilized and availble if needed.

( Imbalanced individual who does not mind spending fun time and money in pursuit of knowledge and experience   :o   )
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BruceM

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Re: Solar Split System Inverter Air Conditioners
« Reply #12 on: July 26, 2019, 03:44:58 PM »
Grid tie inverters are designed for just this application; but you could put the batteries in essentially float service, charged by the PV, and run the AC during sunny days off a battery connected, stand alone inverter.  The non-grid tie inverter/battery/PV system is then useful as backup power for the grid, especially handy for reduced loads at night with no noise.

You can clean up any off grid PV/inverter setup greatly by adding common mode chokes to the PV charge regulator, and AC output, and keeping the battery and electronics setup away from living space and other wiring so that the strong high frequency emissions of the PV charge regulator and inverter don't get picked up by other circuits and spread through the house.  Cheap health insurance.


veggie

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Re: Solar Split System Inverter Air Conditioners
« Reply #13 on: July 26, 2019, 04:23:22 PM »

"You can clean up any off grid PV/inverter setup greatly by adding common mode chokes to the PV charge regulator, and AC output, and keeping the battery and electronics setup away from living space and other wiring so that the strong high frequency emissions of the PV charge regulator and inverter don't get picked up by other circuits and spread through the house.  Cheap health insurance."


Fortunately, the panels, battery bank, charge controllers and engine are far from the dwelling so the only thing running to the mini-AC unit would be the 120 VAC wires from the various possible sources.
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - Lease/Neville Alternator
- Kubota Z482 - 4kw
- JiangDong R165 Air cooled - 2 kw

glassblower

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Re: Solar Split System Inverter Air Conditioners
« Reply #14 on: July 26, 2019, 05:08:17 PM »
I have been working on the design for my next home, 36 solar panels, a listeriod, and have utility as a safety net when I'm too old to fix things. I found an inverter from Schneider Electric that employs "self consumption", that is grid tied when it needs it. In other words, the system will run as much as it can off of the solar, wind, whatever generation you have and will make up the difference from the utility. It will never export or send electric back to the grid, can handle loads bigger than the generator and run off grid. https://solar.schneider-electric.com/product/conext-sw-na/