This article is based on analysis published by SolarQuotes
As more Australian households electrify heating and cooling, solar installers are increasingly asked whether a photovoltaic (PV) system can run their air conditioners. The short answer is yes – but only if system design is based on how modern air conditioners actually behave electrically.
For solar installers, it is key to note that air conditioning is now a core consideration for residential solar design. Understanding inverter behaviour, separating thermal from electrical ratings, and designing around real-world load profiles allows solar to carry most of the daytime load – with batteries handling the rest.
From on-off to inverter control
Older air conditioners used basic on-off control. When the room temperature drifts above or below the set point, the compressor switches fully on. Once the set point is reached, it switches off again.
Modern inverter air conditioners work very differently. Instead of cycling on and off, the compressor continuously modulates its output anywhere from close to zero up to full power. This delivers more stable indoor temperatures, higher efficiency and less mechanical stress from hard starts.
For solar design, this matters. Air conditioning loads are no longer fixed or binary – they are variable and dynamic.
How the control system manages power
Inverter air conditioners rely on control algorithms that constantly compare the actual room temperature with the set point. The greater the difference, the more power the system draws. As the temperature approaches the target, output ramps down smoothly to avoid overshooting.
Once a space is conditioned, many systems settle at well below their maximum electrical demand. For installers, this explains why daytime solar can cover a large share of cooling or heating – even when the air conditioner’s nameplate rating looks intimidating.
Thermal output versus electrical input
One of the most common misunderstandings comes from marketing labels.
A 14 kW air conditioner refers to thermal output – how much heating or cooling the unit can deliver, not how much electricity it consumes.
Because air conditioners operate as heat pumps, electrical input is much lower. For example:
- A 14 kilowatt (kW) unit with a coefficient of performance (COP) of 3 draws around 4.7 kW electrically
- At a COP of 4, electrical demand drops closer to 3.5 kW
For solar and battery sizing, the electrical rating is what counts, not the headline thermal number.
Can solar really cover air conditioning?
At full output, air conditioners can still draw substantial power. A unit with a 7 kW electrical peak will only be fully covered by solar under ideal conditions, and usually only briefly.
However, inverter control works in solar’s favour. Once the room reaches temperature, demand typically drops sharply. This makes daytime solar coverage far more achievable than many customers expect.
Batteries can smooth the remaining gaps, but installers need to consider two separate factors:
- Battery power (kW): To handle ramp-up and short surges
- Battery energy (kWh): To maintain temperature into the evening
Timing and building performance matter
Pre-cooling or pre-heating during peak solar hours is one of the most effective strategies. By stabilising the building earlier in the day, the battery only needs to maintain temperature after sunset rather than meet a large initial load.
Results depend heavily on the home’s thermal envelope. Many Australian houses leak heat and cool rapidly. Improving outcomes means addressing draughts and air gaps, glazing quality and insulation levels.
Adding internal thermal mass, such as exposed masonry, can further slow temperature drift in non-tropical climates.
What installers should focus on
When designing systems to support air conditioning, installers are advised to discuss:
- Electrical input ratings, not thermal capacity
- Seasonal usage patterns
- Overnight and early-morning operation
- Available load data from smart meters or circuit monitoring