Solar power for A/C unit, installer in Chaing Mai?

[davehowden]

Hello all,

Does anybody have any experience of having a solar powered A/C unit installed here in CM?

Many thanks

Dave

[Duvidl]

I didn't think a solar cell (or dozens of them, for that matter) could produce nearly enough current to power an air conditioner. Who makes these?

[MaeJoMTB]

Impossible,

Your entire property would need to be covered in solar cells.

[johng]

My 9000 BTU aircon uses about 3.8 Amps when the compressor is running.

So ignoring power factor and losses for the moment 3.8 x 235 = 893 Watts

so about 10 100W solar panels going full tilt + 1 more for the inverter loss might be possible.

[MaeJoMTB]

My 9000 BTU aircon uses about 3.8 Amps when the compressor is running.

So ignoring power factor and losses for the moment 3.8 x 235 = 893 Watts

so about 10 100W solar panels going full tilt + 1 more for the inverter loss might be possible.

Why are my air-con units on 15A fuses then?

[MaeJoMTB]

My 9000 BTU aircon uses about 3.8 Amps when the compressor is running.

So ignoring power factor and losses for the moment 3.8 x 235 = 893 Watts

so about 10 100W solar panels going full tilt + 1 more for the inverter loss might be possible.

Why are my air-con units on 15A fuses then?

When they startup they can use more Amps, my aircon (12k BTU inverter) uses when running 3.9 amps but the manufacturer recommends at least a 10amp breaker.

So the solar cells would need to be 3x more than needed for normal running.

[johng]

The fuse is to protect the wire in case of a short circuit.

To get over the startup high current draw maybe a battery or 2.

[cloudhopper]

Maybe this is of assistance to the OP

http://www.saveenergyasia.com/htmlsite/products/solaraircon.html

Very interesting concept - I too was thinking photovoltaic after the OP but this is similar to using a propane flame for refrigeration.

[canman]

Maybe this is of assistance to the OP

http://www.saveenergyasia.com/htmlsite/products/solaraircon.html

What am I missing here; this makes no sense at all to me. Why would adding heat into a heat pump system designed to remove heat increase its efficiency? If it was reverse cycle and being used to heat a room I could see how this would work. To me you would be better off pairing up a heat exchanger to the compressor and radiator to heat your hot water.

[Dellboy218]

3 phase induction motors like on your compressor will take 6-8 times its normal running current on startup. One advantage of an inverter drive where it maybe left running and loaded/unloaded.

[Mousehound]

Maybe this is of assistance to the OP

http://www.saveenergyasia.com/htmlsite/products/solaraircon.html

What am I missing here; this makes no sense at all to me. Why would adding heat into a heat pump system designed to remove heat increase its efficiency? If it was reverse cycle and being used to heat a room I could see how this would work. To me you would be better off pairing up a heat exchanger to the compressor and radiator to heat your hot water.

I think the efficiency comes from the solar system heating the chemicals that are then passed into a chamber under pressure where they vaporise and then are cooled off to liquefy again. The efficiency is in that the heating of the liquid is avoided so saving power. The interesting thing seems to be that the hotter it is the more efficient the system, unlike solar electricity systems where it seems there is a drop off in efficiency once the temp gets really hot.

I can't understand why solar assisted aircons are not more popular in Australia - so what is the downside?

[cloudhopper]

Downside is that the solar collector needs to be located between the evaporator and the compressor, and also be exposed to the afternoon sun. Easier to do new than retrofit in most cases I imagine...it's a great concept though....

[cloudhopper]

Maybe this is of assistance to the OP

http://www.saveenergyasia.com/htmlsite/products/solaraircon.html

What am I missing here; this makes no sense at all to me. Why would adding heat into a heat pump system designed to remove heat increase its efficiency? If it was reverse cycle and being used to heat a room I could see how this would work. To me you would be better off pairing up a heat exchanger to the compressor and radiator to heat your hot water.

Heat always flows from hot to cold so the compressor must get the cool refrigerant up to a much higher temp than the outside air in order for the heat to flow out of the system. Preheating the the cool gas by solar will reduce the work required by the pump to reach the target temp.

[Naam]

LORD have mercy on them aircon eggsburts!

[Chicog]

Is this snake oil then? Seems almost too good to be true.

Q. WILL IT BE CHEAPER TO RUN?

A. YES. By converting the air conditioning unit to Solar it will use approximately 60% less electricity and therefore your usage will be less which means you will pay less to the electric supplier.

Q. WHAT ARE THE COSTS?

A. We have several different packages available and it all depends on your current system. Prices start at around US$400 (THB12,000)

[Dellboy218]

Maybe this is of assistance to the OP

http://www.saveenergyasia.com/htmlsite/products/solaraircon.html

What am I missing here; this makes no sense at all to me. Why would adding heat into a heat pump system designed to remove heat increase its efficiency? If it was reverse cycle and being used to heat a room I could see how this would work. To me you would be better off pairing up a heat exchanger to the compressor and radiator to heat your hot water.

Heat always flows from hot to cold so the compressor must get the cool refrigerant up to a much higher temp than the outside air in order for the heat to flow out of the system. Preheating the the cool gas by solar will reduce the work required by the pump to reach the target temp.

The heat is the result of compressing a gas. Similar to any tyre pump that gets hot. Your outside unit is a condenser which cools the 'now liquid' refrigerant. It is the compressor that is the driving force. In the other system it is the heat acting on a 'collector ' and subsequent boil off that is the driving force.

[Naam]

What am I missing here; this makes no sense at all to me. Why would adding heat into a heat pump system designed to remove heat increase its efficiency? If it was reverse cycle and being used to heat a room I could see how this would work. To me you would be better off pairing up a heat exchanger to the compressor and radiator to heat your hot water.

Heat always flows from hot to cold so the compressor must get the cool refrigerant up to a much higher temp than the outside air in order for the heat to flow out of the system. Preheating the the cool gas by solar will reduce the work required by the pump to reach the target temp.

The heat is the result of compressing a gas. Similar to any tyre pump that gets hot. Your outside unit is a condenser which cools the 'now liquid' refrigerant. It is the compressor that is the driving force. In the other system it is the heat acting on a 'collector ' and subsequent boil off that is the driving force.

you nearly got it mate it is correct that it's the compression of the gas that heats it up but the condenser does not cool down the "now liquid" gas as the compressor pumps the gaseous refrigerant through the condenser in order to liquify the gas by cooling it down.

if the refrigerant was liquid before it is "sucked" into the compressor (that happens under certain circumstances) the latter would be damaged in no time. (physics 101: liquids cannot be compressed!).

cloudhopper

Heat always flows from hot to cold so the compressor must get the cool refrigerant up to a much higher temp than the outside air in order for the heat to flow out of the system.

Honourable Sir Cloudhopper, Esq.;

i think you are aware that i had open heart surgery (5 bypasses, 4 coronary and 1 artery) a few years ago. you are therefore humbly requested to refrain from making statements such as the afore-mentioned because it could kill me instantly.

note to LORD: i repeat... please have mercy on all resident aircon eggsburts.

[Dellboy218]

The heat is the result of compressing a gas. Similar to any tyre pump that gets hot. Your outside unit is a condenser which cools the 'now liquid' refrigerant. It is the compressor that is the driving force. In the other system it is the heat acting on a 'collector ' and subsequent boil off that is the driving force.

you nearly got it mate it is correct that it's the compression of the gas that heats it up but the condenser does not cool down the "now liquid" gas as the compressor pumps the gaseous refrigerant through the condenser in order to liquify the gas by cooling it down.

if the refrigerant was liquid before it is "sucked" into the compressor (that happens under certain circumstances) the latter would be damaged in no time. (physics 101: liquids cannot be compressed!).

cloudhopper

Heat always flows from hot to cold so the compressor must get the cool refrigerant up to a much higher temp than the outside air in order for the heat to flow out of the system.

Honourable Sir Cloudhopper, Esq.;

i think you are aware that i had open heart surgery (5 bypasses, 4 coronary and 1 artery) a few years ago. you are therefore humbly requested to refrain from making statements such as the afore-mentioned because it could kill me instantly.

note to LORD: i repeat... please have mercy on all resident aircon eggsburts.

Absolutely right of course. Its the way wot I rote it. It desuper heats it and somewhere in that coil of piping the all the gas will have changed to liquid.

[cloudhopper]

cloudhopper

Heat always flows from hot to cold so the compressor must get the cool refrigerant up to a much higher temp than the outside air in order for the heat to flow out of the system.

Honourable Sir Cloudhopper, Esq.;

i think you are aware that i had open heart surgery (5 bypasses, 4 coronary and 1 artery) a few years ago. you are therefore humbly requested to refrain from making statements such as the afore-mentioned because it could kill me instantly.

note to LORD: i repeat... please have mercy on all resident aircon eggsburts.

Well feel free to correct me then Dr - at the risk of causing you another blockage I still stand by my statement that the compressor heats up the refrigerant (by compression PV=nrT) to a much higher temp than outside in order for the removed heat to flow into the outside air.

[maprao]

So back to the topic, is anyone in Thailand actually doing this?

I do not think it will work but I am waiting for someone like crossy to come and tell me why.

[Naam]

Well feel free to correct me then Dr - at the risk of causing you another blockage I still stand by my statement that the compressor heats up the refrigerant (by compression PV=nrT) to a much higher temp than outside in order for the removed heat to flow into the outside air.

i humbly apologise Sir! my crooked old eyes distorted your sentence "heat flows from hot to cold" into "heat flows from cold to hot".

you are hereby declared a clear winner, receive 999 points and are allowed to participate in the next round of the game

[scorecard]

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The fuse is to protect the wire in case of a short circuit.

To get over the startup high current draw maybe a battery or 2.

From a total layman - would it be possible to start the A/C on normal mains current then flip over to solar power after say 5 seconds or whatever?

[Naam]

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The fuse is to protect the wire in case of a short circuit.

To get over the startup high current draw maybe a battery or 2.

From a total layman - would it be possible to start the A/C on normal mains current then flip over to solar power after say 5 seconds or whatever?

that's not possible because all units have a timer relay that prevents a compressor restart for several minutes after a stop even if that stop lasts only a second. the reason for this delay is to avoid the compressor starting against already built-up pressure which would cause an amp load much higher than the usual high starting amps.

[Naam]

johng, on 15 Apr 2015 - 17:13, said:

The fuse is to protect the wire in case of a short circuit.

To get over the startup high current draw maybe a battery or 2.

not only batteries but also an inverter which has the required output.

[ultipost]

I am the project manager of an international team that designed a series of Zero Energy Houses, primarily in the Netherlands and incorporated in Grenada. What's relevant for this post is that we use solar PV panels as construction material, which required the development of custom profiles and an innovative roof design. We use a special type of solar PV (CIGS) which has a matte black look and several other properties that make them suitable for this new application. Those interested check this link: https://docs.google.com/document/d/1bvHrseT6mk89D-jD9QXvrYfg4MspLrC1-STWvOQ-Gts/edit

We scheduled building the first prototype and as I live in Thailand (when I not work abroad 6-8 months per year) and am here when the prototype is ready, I thought to build it up behind my house (as a guesthouse). First, this seemed to be not possible as the electricity company had not renewed the feed-in arrangements. Since very recently it was announced that they do accept electricity again. However, when we applied at the electricity company they said to my Thai wife that only 2 companies in Thailand are allowed to install solar systems an tie them to the grid. I could not believe my ears... Inverters are warranted to comply with international standards and Thailand will be no exception. When this is indeed true I will install the prototype in Europe, probably France.

When the solar PV market would be free, prices of solar panels + inverter could be $ 1.20 - 1.40 per W (at 3-4 kW system) plus installation materials and labor. Working off-grid would be possible, preferably by using A/C's with DC compressors and a DC/DC converter (aka solar A/C's - but not all are created equal). I do not know whether they are available in Thailand.

I hope this helps!

[Doisaketdreamer]

EyeKandi Solar in Chiang Mai installs a system made  by PAC that powers the compressors directly from solar panels. 20 panels to one 76,000 BTU compressor.