Solar inverter size calculator
Find the inverter size in kW for the appliances you want to run, including the start-up surge of ACs and motors.
Recommended inverter1.5 kW
- Minimum size
- 1.01 kW
- Running load (Everything on at once)
- 811 W
- Start-up peak (When the biggest motor or compressor starts)
- 1,111 W
- Adds 25% headroom to the running load and assumes the inverter can briefly supply about twice its rating to start a motor.
- Check that your panels' total kW and voltage fit the inverter's PV input range, and that the battery voltage matches.
About this calculator
An inverter has to handle everything you switch on at once, plus the jolt when a fridge, AC or water motor starts. Too small and it trips. Much too big and you pay for capacity you never use.
Count your appliances and the calculator finds the running load, the start-up peak and the standard inverter size that covers both.
How it works
- Running load is the sum of every appliance's running watts.
- Start-up peak adds the extra draw of the single biggest motor or compressor starting, which is up to three times its running watts.
- Minimum size is the larger of running load × 1.25 and start-up peak ÷ 2.
- The result is rounded up to the next common size: 1, 1.5, 2, 3, 4, 5, 6, 8, 10, 12 kW and up.
Common questions
- What size inverter do I need for a 1.5 ton AC?
- A 1.5 ton inverter AC runs at about 1.6 kW. With fans, lights and a fridge, most homes need a 3 to 4 kW hybrid inverter.
- Is kVA the same as kW?
- Not quite. kW is real power and kVA includes power factor. Many home inverters in Pakistan are sold by kW, and for home loads the two are close.
- Should the inverter match my panels?
- The inverter's PV input should cover your panel array. Many hybrid inverters accept panels up to about 1.3 times their rating.
A guide only. Your installer should check the inverter's datasheet against your panels and battery.