Before purchasing any inverter, the following questions should be made clearly: DC voltage, loading size and type . Generally, DC voltage of the inverter has only one grade, users can choose corresponding inverter according to DC power supply. Loading size and type are the important factors that users should consider when select any inverter. Maximum output power of inverter is fixed, if choose loading with compressor, its starting power will exceed several times of rated power, so inverters with big output power have to be chosen as a result. 

When determining continuous power and surge (peak/starting) power, you need to consider how much power do your devices require to start up (surge power), and also the continued running requirement (continuous power).

What is meant by the terms of "continuous 2000 watts" and "peak/surge 4000 watts"? Some devices with motor require an initial surge of power to start up ("surge power" or "peak power"); once started, they require less power to continue to operate ("continuous power").

To calculate approximate surge power:

   Watts X 2 = Surge power

This formula yields a close approximation of the surge power, though some may require even greater ones.

Note: induction motors such as air conditioner, refrigerator, freezer and water pump may have a start up surge of 3 to 7 times than the continuous ratings.

The below tales are general rated power of some home devices, the induction motors are marked with *.

 Common appliances:

Common tools:

Pumps and air conditioners:

Note: the wattages given above are estimated, the actual ones required may differ from those listed. Check the nameplate to determine the actual wattages required.