Solar Powered Air-conditioners stand alone

Solar panel powered air-conditioners in South Australia – too good to be true?

For the 1st time in Australia there is a reverse cycle split air-conditioner powered directly from sunlight, through 4 photovoltaic solar panels feeding electricity straight into the air-conditioning unit.

Air-conditioning is the number one energy user in the average Australian building.  The SA government website (www.sa.gov.au/energy/saving energy at home) shows nearly 40% of all electricity usage in homes is for heating and cooling.  To us as electricians specialising in sustainable energy usage, an air-conditioner powered directly from sunlight sounds like an exciting green product we should be getting out into the market.  However, in keeping with our ethos of providing an honest and trustworthy service, we have done some investigating into this product for South Australian conditions – is it too good to be true?

With this 3.5kW SolarAir air-conditioner, sunlight is converted to electricity by 4 x 250 watt photovoltaic solar panels which is then fed directly into the compressor unit as direct current (DC). It is is designed to accept a total of 1000 watts (1 kW) peak power generation.  (It is not to be confused with solar thermal air-conditioners or hybrids. These sorts of air-cons use fluid heated by solar energy in a thermally driven refrigeration process. We are not installing that type of air-conditioner as we believe they are inefficient and too expensive to install).

The SolarAir air-conditioner does not feed electricity into the grid like your typical grid connected solar systems do, but just takes what it needs from its 4 panels to run the air-conditioner on a sunny day, and is topped-up with grid power if it’s very cloudy, or at the very end or beginning of the day.

Brilliant. What a brilliant and, given Australia’s climate, incredibly simple idea.  Why has no-one done it before?  As our probing reveals, in certain situations in South Australia it really is that simple, and that good.  However, as with most things in life, there are a few things you need to take into consideration before opting for this type of air-con.

At night time these air-cons get their power directly from the grid just like a normal air-conditioner. The efficiency of air-conditioners is often compared using the Co-efficient of Performance (COP).  The SolarAir air-conditioner has a COP of 4 which is not bad, but is also not the most efficient air-conditioner on the market today. However, during the day the COP doesn’t matter because the SolarAir air-con isn’t running on electricity from the grid.  The trick is, use the SolarAir air-con during daylight hours when it is powered directly from the sun, and the value of the COP becomes irrelevant.  At night time, the air-conditioner will run on normal electricity sources, so getting the greatest benefit from one of these SolarAir air-cons will depend on whether you mostly use your air-cons during the day, or at night – or whether you would love to use it during the day but just don’t because of the cost of electricity!

In some cases it will be more logical to install rooftop solar on your building, and install a top of the range super-duper efficient air-con (which will then be powered by your rooftop panels during daylight hours anyway along with all your other appliances).  However, not everyone is in a position to install rooftop solar panels, particularly on those buildings which already have rooftop solar and will lose their lucrative feed-in tariff if they were to add any more.  One of the main advantages of the SolarAir air-con therefore is for those people who would like to add more solar panels to their roof top array but cannot because they would lose their feed-in tariff.  By installing the SolarAir air-con they will be able to use a further 1 kW of solar power if they run their air-con during the day, because the 4 solar panels which come with the SolarAir air-conditioner are additional to, and do not form part of, the existing rooftop solar array. Depending on your electricity usage during the day, and due to the fact you are not using power from your current solar array on air-conditioning, you may even be able to export more of your solar power to the grid. Nice work for those on a high feed-in tariff.

So let’s compare costs. The website www.sustainability.vic.gov.au/service-and-advice contains a running cost calculator which shows indicative costs of running different brands of appliances and allows you to compare the energy consumption of each.  As an example, if we plug into this calculator a daytime usage of 5 hours/day for 3 months in summer and a daytime usage of 5 hours/day for 3 months in winter (which is the averaged amount of solar power available on any day of the year in South Australia according to the Bureau, minus 0.6 in transmission losses), we will see that a super-efficient air-con currently on the market today will cost roughly $5,500 over its 10 year lifetime (comprising running costs plus initial cost of the unit). Given the SolarAir air-con uses virtually no electricity for that equivalent averaged amount of daylight hours, its total cost in comparison will be $4,000 (a savings of $1,500).  The calculator uses current electricity price in South Australia of $0.40c – this will no doubt increase over 10 years so one could expect the savings to be more.

So should you, or should you not, get a SolarAir air-con?  The following scenarios are those in which we think it would be a good investment to purchase them in South Australian conditions:

  • The air-conditioner is used in the home or office during daytime and you already have a rooftop solar system in place, but it does not provide enough power to cover your daytime usage.  Yet if you added more panels to your rooftop solar you would lose your lucrative feed-in tariff. Installing a SolarAir air-con in these situations and running it during the day means you are paying next to nothing for electricity to run the air-con, and it may also free up solar power from your rooftop solar which can then be exported back to the grid. Examples for this type of use might be:
    • Home offices or small commercial offices (the SolarAir air-con is a 3.5kW system covering 30m2)
    • Stay at home mums and dads with young kids who don’t use much air-con at night
    • Elderly people preferring staying at home
    • Small commercial offices and shops
  • Mining camps – many mines are located in remote sites that are not grid connected and electricity is usually produced by diesel powered generators.  Driven by high fuel and transportation costs the price for electricity generation is normally high.  In certain scenarios the use of SolarAir air-conditioners could result in considerable cost savings by reducing the quantity of diesel used.
  • Military camps – similar to the mining camp scenario, many military camps are also in remote areas which generate electricity from diesel powered generators.
  • Tenanted units that don’t have solar rooftop solar (it is possible to take the SolarAir air-cons if you move)

Given the SolarAir air-con falls back to using power from the grid at night time (ie. coal fired power stations), the next big question on our lips is ……. In those times when we are not running the air-con during the day can we store the power from the sun into batteries, so that we can still use the suns energy to run the air-con at night?   Yep folks, it seems like the feasibility of this is just around the corner.  Stay tuned for our next blog on battery storage of solar power.

If interested in SolarAir air-cons call Kevin from SolarAir SA  on mob: 0411-886 874  or visit the SolarAir website www.solarairsa.com