Watts to Watt Hours (W to Wh) Conversion Calculator
Wh × hrs =
Conversion formula: Wh = W × hrs
What Is Watt (W)?
Watt is the S.I unit of power. Power, in turn, is the rate at which energy is transferred within a system. In electrical terms, power is the energy transfer rate per second within a circuit.
Going by the definition of power, watt is a measure of the amount of energy transferred per second within a circuit. In other words, 1 watt of power equals the transfer of 1 joule of energy in 1 second.
What Is a Watt-Hour (Wh)?
Watt-hour is a unit of energy. It is typically used to measure energy usage by electrical devices/appliances or energy production by energy sources like batteries.
Watt-hour represents the energy consumption or energy production when a device consumes or produces a certain amount of power for a specific number of hours. In other words, when a device consumes one watt of power for one hour, it would have consumed one watt-hour of energy.
More examples: If a solar panel produces 50 W for 5 hours, it would have produced 250 Wh of energy. Then, if a solar refrigerator uses 25 W for 3 hours, its energy usage would be 75 Wh.
Why Calculate Watt-Hours?
We calculate watt-hours for many reasons, one of which is to manage our electricity usage. When you know the total watt-hours of the appliances in your home, you can forecast your electricity usage. This way, you have an idea of what to expect when the energy bill comes.
If the bill is way more than what you can afford, you can calculate the watt-hours of each appliance to know how much electricity they are using. Once you know how much energy each appliance uses, you get a sense of where to cut down on electrical energy consumption.
For instance, an incandescent light would most likely have higher watt-hours than an LED light. So, you can consider changing your incandescent lightbulbs to LED lightbulbs to cut down your total energy usage.
How to Calculate Watt-Hours (Wh) of an Appliance
Calculating watt-hours of an appliance is pretty straightforward when we know the power consumption and time period of power consumption (in hours). In such situation, all we have to do is multiply both values to get the watt-hours.
Formula: watt-hour = watt x hour
So, if we have a solar gate opener with a wattage of 10W, after running for 3 hours, it would have consumed the following amount of electricity:
= 10 x 3 = 30 Wh.
In cases where we do not know the wattage but know the voltage, amperage, and hours, we can calculate the watt-hours of household appliances by multiplying the value of all three quantities together.
Formula: watt-hour = volts x amps x hour
So, if we have a solar-powered camera running on a 12v battery, drawing 8 amps for 2 hours, its energy consumption would be:
= 12 x 8 x 2 = 192 Wh
In all the calculations above, we pretty much just estimate watt-hours from appliance specifications.
In reality, the result from your calculation will not be exactly the same as the real thing because no electric circuit is 100% efficient.
So, if you want it, you can the get actual watt-hours with an electricity usage monitor.
How to Calculate Watt-Hours (Wh) of a Battery
To calculate watts-hours of a battery, all we have to do is multiply the battery voltage (volts, v) and battery capacity (amps-hour, Ah).
Formula: watt-hour = volts x amps-hour
So, if we have a solar power system whose 12v battery has a capacity of 100Ah, its energy in watt-hour would be:
= 12 x 100 = 1200 Wh.
Then we can convert watt-hours back to battery capacity by dividing the value of watt-hour by battery voltage:
= 1200 ÷ 12 = 100 Ah
Converting watt-hours to voltage is also possible when we divide it by capacity:
= 1200 ÷ 100 = 12 v
How to Convert Watts to Watt Hours (W to Wh)
To convert watts to watt-hours, all we have to do is multiply the value of watts by the value of hour.
watt-hour = watts x hour
Example: Watts to Watt-Hours (W to Wh)
So, if we have a solar flood light with a wattage of 100 W, and it runs for 8 hours, here’s how much energy it will consume:
= 100 x 8 = 800 Wh.
Similarly, say we have a solar power system whose solar panels have a wattage of 200 W. If the panels are exposed to the sun for 5 hours, here’s an estimate of how much electricity they’ll generate:
= 200 x 5 = 1000 Wh.
What’s the Difference Between Watts and Watt-Hours?
The primary difference between watts and watt-hours is the quantity they measure.
While watts measure how much power electrical equipment consumes or generates, watt-hours measure the energy usage or production of an electrical system or device.
While watts are an SI unit, watt-hours are not an SI unit. In many cases, you’ll only find watt-hour (Wh) being used as a unit for electrical energy.
What About Kilowatt-Hours (kWh)?
Kilowatt-hours is a measure of the energy consumed or produced when a certain amount of power (in kilowatts) is used or given off during a given time. In other words, one kilowatt-hour of energy is generated or used when one kilowatt of power is consumed or emitted for one hour.
Like watt-hour (Wh), kilowatt-hours (kWh) is a unit of energy. However, kilowatt-hour measures the energy at a higher magnitude than watt-hours.
The metric prefix kilo distinguishes kWh from Wh in that kWh measures energy in thousands while Wh does so in units.
How to Convert Watts to Kilowatt Hours (W to kWh)
When you know how long a device or appliance has been operating, converting watts to kilowatt-hours is straightforward.
First, you have to convert watts to kilowatts by dividing the value of watts by 1000. Next, you’ll multiply the value of kilowatts by the number of hours the device or appliance has been operating. This will give us the conversion of watts to kilowatt-hours.
kilowatt-hour = (watt ÷ 1000) x hours
So, say we have a solar panel whose wattage is 100 W. If this panel is exposed to intense sunlight for 4 hours, how many kWh of electricity will it generate?
kWh of the solar panel = (100 ÷ 1000) x 4 = 0.4 kWh
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