Many customer ask us what is kW and kWh. Getting clear their meaning is very useful for designing the off-grid solar system. Hope you find it useful.
What are kW and kWh, what do they stand for?
One of the most common question by our customer is, what is kw and kwh? They get confuse about the meaning, and sometime it will bring more budget for their system.
In this blog, we will talk about what is kw and what is kwh.
What is the difference between a kW and kWh?
k stands for kilo. Which means 1000.
W stands for Watt
h stands for hour
What is kW?
So kW means kilowatt, which is 1000 Watts. It is a measure of power. Every appliance will have a lable, that you will see how many Watt for this appliance.
For example, the kettle in my family is 600watt, 600watt = 0.6kW. Thi is a measure of power. For home device, the biggest home appliance is like air conditioner, water pump.
And for the solar panel, the kW also means the peak power.
Like a 550w solar panel, it will give 0.55kw in STC condition, in the biggest biggest sun.
And for the inverter, like a 5kW inverter. It means it can supply 5000watt at same time. The biggest load should be under 5kW.
What is kWh?
kW measures power, and kWh measures energy.
If my 0.6kW kettle is using in 1hrs, which not possible. That the power comsumption is
0.6kW * 1hr= 0.6kwh
And back to the solar panel, in STC condition, if the big big sun shine on the 3kw solar panel in one hour 60 minutes, then it will give you
3kW * 1hr=3kw power. Which you can sell to local power company or kept in the battery.
Why is the understanding the meaning is important?
It is very common for people to mistakenly between kWh and kW.
But when they design a solar system, they will say, I need a 50kw solar power system.
But they mean they need a solar system which give them 50kwh in one day, not what we think of 50kw solar panel. If we quote them 50kw solar system, that is about $52,000, this is a skyrocket price for people.
Actually, they only need a 10kw solar system to cover 50kwh each day. And 10kw off-grid solar system price is about $10,000 with 16pcs gel battery.
Do you see the different bewteen kW and kWh?
That is the differnet about $10,000 and $52,000.
How do kWh relate to batteries?
Just like a swimming pool, the more battery kWh capacity, the bigger swimming pool is.
The more energy (kWh) a battery has, the more you can store and the longer it will last, it will supply more using time for the home appliance.
Allon has over 10 years experiences in off-grid project. Including diesel or solar area, he always have his idea to design a perfect system for you.