How many panels to run an AC?
The answer depends on one thing nobody asks first: do you want it running at night?
The short version
- • A 1.5 ton inverter AC uses roughly 1 to 1.5 units an hour.
- • Running an AC in daylight is a panel question. At night it is a battery question.
- • Running an AC on battery costs far more than running fans and lights.
Everyone asks this. The usual answer is a panel count, which is the easy half.
The half that decides your budget is whether you want the AC on after sunset.
What an AC uses
A 1.5 ton inverter AC uses roughly 1 to 1.5 units an hour once the room is cool. An older non-inverter unit uses more.
Run one for eight hours and that is roughly 8 to 12 units. Two of them is close to 20 units a day. That is the whole daily output of a 5kW system.
In daylight, it is a panel question
One kilowatt of panels makes about four units a day.
| What you want to run | Units a day | Panels needed for it |
|---|---|---|
| One AC, 6 daylight hours | 6 to 9 | About 2 to 2.5kW |
| Two ACs, 6 daylight hours | 12 to 18 | About 3 to 4.5kW |
Rough figures to set expectations, not a design. Your real usage is on your bill.
At night, it is a battery question
This is where budgets break.
To run an AC after sunset you need the grid or a battery. If you have net metering, the grid already does this, and it is by far the cheapest way.
To do it on battery during load-shedding, the battery has to hold all those units, and the inverter has to handle the AC starting up. That is a much bigger system than one running fans and lights.
Ask this before comparing hybrid quotes
"Will this run my AC during a power cut, and for how many hours?" A system that backs up fans and a system that backs up air conditioning are different products at very different prices.
Cheaper moves first
- Replacing an old non-inverter AC cuts the load before you buy a single panel
- Raising the thermostat two degrees changes the daily units noticeably
- Cleaning the filters restores efficiency you lost quietly
- Backing up one bedroom instead of the whole house is a fraction of the battery
It sizes from your bill and your roof, which is the only way to get this right.
Size my system