Nothing kills the comfort of a cool room faster than the AC cutting out the moment the power does. The size of inverter your air conditioner needs comes down to two numbers: how much power it draws while running, and the short, much bigger burst of power it needs the instant the compressor starts. Get this right, and your AC runs the way it should during any outage. Get it wrong, and you’ll be resetting a tripped system every time the compressor kicks in.

How much power does an air conditioner really use?

A standard 1-tonne (roughly 1HP) air conditioner draws around 1,200W while running, but the compressor’s startup surge can briefly demand two to three times that. This surge is the real reason AC sizing trips people up: an inverter that comfortably handles the running wattage can still fail if it can’t absorb that short spike. This is also why the AC needs to be on a system with a genuine pure sine wave inverter. A rough or stepped waveform causes compressor motors to hum, overheat, and wear out early.

• Small room AC (0.5HP to 1HP): lighter running power, still needs surge headroom
• Standard 1-tonne AC (1HP): moderate running power, meaningful startup surge
• Larger AC units (1.5HP and above): higher running power, bigger surge, needs a properly sized system

Which Sun King system fits your AC?

• A single 1-tonne (1HP) AC, alongside typical household appliances: the PowerHub Plus, with its 3.3kW inverter and 5kWh battery, is built for this. Running it with two batteries gives you the fullest comfort; one battery still comfortably covers a lighter, roughly 0.5HP-equivalent AC.

• An AC plus other big appliances running together, like a freezer or pump: this usually calls for a custom PowerHub build sized around your full home’s energy needs.

• Larger commercial or multi-unit AC setups: these are sized individually. Sun King’s PowerHub platform scales up to 30 kW of inverter power through paired units, but the right configuration depends on a proper assessment, not a standard package.

See the full PowerHub specifications here and contact an agent to start your journey to reliable solar power.

Why the compressor surge matters more than the running wattage

Most people size an inverter by looking at the AC’s running wattage alone, and that’s the mistake that leads to trips and resets. The moment the compressor starts, it can demand well above its steady running power for a few seconds. An inverter needs enough surge capacity to absorb that, and the battery needs to be able to deliver that current without its voltage dropping. Sun King’s PowerHub inverters are built with this surge in mind, so a properly sized system starts and runs the AC the way it’s designed to, rather than living on the edge of an overload every time it cycles on.

Does every AC need the same size inverter?

No. Newer, energy-efficient air conditioners with variable-speed compressors use far less power to start than older, fixed-speed units, because they ramp up gradually instead of switching on at full power. If your AC’s outdoor unit is labelled as energy-efficient or shows a variable-speed rating, it will place a gentler demand on your inverter than an older, standard AC of the same size. Either way, the safest approach is to size around your actual appliances and everyday energy needs rather than guessing.

Frequently Asked Questions

What size inverter do I need for a 1-tonne AC? For a single 1-tonne (1HP) AC alongside typical household appliances, the PowerHub Plus with its 3.3kW inverter is Sun King’s standard recommendation. Homes adding more big appliances on top should look at a custom-sized system instead.

Why does my inverter trip when the AC starts? An inverter usually trips because it isn’t sized to absorb the compressor’s brief startup surge, not because there isn’t enough solar generation. The fix is a properly sized inverter and battery from the start, confirmed through a proper assessment rather than guesswork.

Can one system run an AC and a fridge together? Yes, but it needs to be sized for both running at once. The PowerHub Plus can comfortably handle two big appliances together, such as an AC and a fridge, which is why Sun King always recommends an assessment before finalising a system for multiple heavy appliances.

Does a bigger AC always need a bigger inverter? Generally yes, since a larger AC draws more running power and a bigger startup surge. But the AC’s compressor type matters too. A modern, variable-speed AC places a gentler demand on the system than an older, fixed-speed unit of the same size.

What’s the next step?

Sizing an inverter for your air conditioner comes down to two things: the running wattage and the startup surge, plus whatever else you want running alongside it. For most homes with a single 1-tonne AC, the PowerHub Plus is the confident recommendation. Bigger or combined energy needs deserve a proper look before you commit to a system.

Every PowerHub purchase includes a free sizing assessment. Explore the PowerHub range to get started.