k = kilo, means “one thousand”
W = Watt, which is a measure of power
h = hour
kWh=kW × h
kW stands for kilowatt. And a kilowatt is simply 1,000 watts. kWh stands for kilowatt-hour. For instance, a 1000 watt microwave needs 1000 watts (1 kW) power to work, and consumes 1 kWh quantity of electricity per hour.
e.g.：
The output power of Sixclocks-ESS3 is 3000 watts (3kW) and the energy storage capacity is 2.9kWh. That is to say when the ESS3 is discharging, it can support 3 microwaves to work at the same time or one to continuously work for 2.9 hours.
Put simply, the more power it has, the more appliances the system can power concurrently. And the more energy it has, the longer you can power those appliances. And Sixclocks provides energy storage systems covering full power range with expandable storage capacity. So you can choose different products according to your specific needs.