One of the highest energy consumers, if not the highest, in many residential homes is the Air-Conditioning. Depending on your Air-conditioning unit, they can consume an average of 4kW when initially turned on for cooling (much higher in many cases) and may then drop this consumption to around 2.5kW (much higher in many cases) when maintaining the desired temperature. As electricity prices are rising, this high usage can reflect significantly on your wallet. Hence everyone is a bit hesitant turning on the Aircon.
Everybody prefers coming home to a house that is already cool, instead of waiting for 30 mins or longer for it to cool down. If you have a solar system installed on your roof or are looking to in the near future, then you are in luck!
We have run an experiment on our test site to indicate a simple method to try on your home, which may not only enable you to come home to a cooler house but can help to maximise the benefits from your solar system and save on your power bills.
As mentioned previously, most air-conditioners consume the most power immediately after being turned “On”. Once the desired temperature is reached, the air-con will work to maintain this temperature at a lower power usage.
Most modern Aircon units have an inbuilt TIMER and AUTO function. Why not set your aircon timer on Auto to switch “On” before you get home, when there is still solar power being produced (Free Power). Once you arrive home, the house is already cool, and the air-con will use a lower amount of energy to maintain the desired temperature.
A suitable Temperature to set is 22°C-24°C. when you return home, you can adjust the temperature further, but the hard work will have already been done.
Insulation is another important factor when deciding on when to set the timer on the Air-con to turn on.
Good Insulation: If you have a well-insulated home, turning the Air-Con on can be done earlier in the day, and simply turning it off once the solar production drops away. Since the house is well insulated, it may be able to maintain the cool temperature throughout some of the evening or until required.
Moderate Insulation: If you have a moderately insulated house, the perfect time to set the timer on the Air-Con to turn on is the afternoon around 3PM. This method would be even more beneficial if you have panels facing West (West facing panels produce at their peak in the afternoon).
Poor Insulation: If you have poor insulation (e.g., you have cracks in doors and window frames, or no ceiling insulation), then pre-cooling might not be as helpful as it will be offset by warm air leaking in from the outside. However, it may still worth a shot or look to get some quotes for insulation.
Every home will be different, as every solar system is different (Depending on panel orientation, panel tilt, number of panels, seasons etc.). For this reason, we recommend experimenting with this solution at different times and settings.
A very handy tool to work this out quickly and one we recommend with all our systems is home consumption monitoring (often referred to as a smart meter) which allows you to have a clear view of your solar system performance as well as your home power consumption patterns via an app on any smart device. This arms you with the technology to become more energy efficient, and work towards the end goal of becoming energy independent!
We would love to hear from you and see your results. Send through your before and after consumption graphs and the team would be more then happy to assist and see where you can make any further improvements.
See Examples below from our Quest HQ Test site below: (Green being Solar Power produced Blue being your Free solar power consumed, Red being power consumed and paid for from the grid.)
Switching on the Air-con just after 5:30PM, and the spike in consumption can be seen at that time. Most of that energy comes from the grid at an expensive cost of 27-28 cents per kWh and rising. (WA Customers).
Turning on the aircon at around 3PM, you can see the energy usage still spikes, but does so earlier in the day using free solar energy.
Written by Moe – Electrical and Renewable Energy Engineer – Quest Energy
23rd Feb 2021