In this short guide where we explain the difference between solar power amp hours vs watt hours. This is an important topic for anyone building DIY solar system, and we will use the most simple language to explain this.
If you need some basics understanding of electricity, we have a ultimate guide where we break down volts, amps, watts, resistors. It’s written so easy to understand for college student and even a 7th grader. Click here to view
Otherwise, let’s continue.
Major Difference Between Amperage Hour And Wattage Hour
Watt Hour is total energy output generated over time.
Amp Hour is total electric charge current passing a point.
A better visual analogy we can give this the following:
What Is Amp Hours?
Amp Hours (Ah) is the amount of current (amps) over time.
For example: 1 Ah = 1 amp for 1 hour
Analogy: Picture a car going 45 mph, after 1 hour the distance traveled is 45 miles. If something is 45 amp running for 1 hour, that’s 45 Amp Hours.
Amp Hours is also the unit used to measure battery capacity
Why Is Amp Hour Spec Important?
Adding deep cycle 12V batteries to your solar system is a key component, and battery capacity is rated in Amp Hours, aka how many Ah can the battery store in a battery.
However, Amp Hour alone can’t tell you everything until you look at the battery’s Watt Hour capacity.
So where does Watt Hour comes into play?
What Is Watt Hour?
Watt Hour (Wh) is the amount of Watts over time, it’s quantify the amount of energy
Watt Hour = Volts X Amps X Hours
1 Wh = 1 watt for 1 hour
- 20 Watt light bulb on for 1 hour, that’s 20 Watt hours
- 20 Watt light bulb on for 2 hours, that’s 40 Watt hours
Most batteries are 12V, so it will be:
12V X 100A X 1 hrs = 120 Watt Hour
Battery Capacity = 12V X 100 Ah = 1200 Watt Hour
This is a critical part of the equation when we design our solar system based on how much we use.
We can use the Watt Hour and reverse the calculation to find voltage required for a system to size our wires.
How Much Is 1 KWh ?
1 Kilowatt Hour is simply 1000 Wh, and 40 KWh is 40000 Wh
Average household in the US uses up to 19000 kWh a year, that’s 52 KWh a day.