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A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a non-SI unit of energy equal to 3.6 megajoules (MJ) in SI units, which is the energy delivered by one kilowatt of power for one hour. Kilowatt-hours are a common billing unit for electrical energy supplied by electric utilities.
1.0 MJ (0.28 kWh) kilojoule: kJ kJ 1.0 ... (kW·h, kW-h) kW⋅h watt-hour: Wh Wh 1.0 ...
More recently, the cost of solar in Japan has decreased to between ¥13.1/kWh to ¥21.3/kWh (on average, ¥15.3/kWh, or $0.142/kWh). [133] The cost of a solar PV module make up the largest part of the total investment costs. As per the recent analysis of Solar Power Generation Costs in Japan 2021, module unit prices fell sharply.
In 1994, the US National Institute of Standards and Technology (NIST) defined "gasoline gallon equivalent (GGE) [as] 5.660 pounds of natural gas." [1] Compressed natural gas (CNG), for example, is a gas rather than a liquid.
For example, when a light bulb with a power rating of 100 W is turned on for one hour, the energy used is 100 watt hours (W·h), 0.1 kilowatt hour, or 360 kJ. This same amount of energy would light a 40-watt bulb for 2.5 hours, or a 50-watt bulb for 2 hours.
The following unit conversions may be helpful when considering the data in the tables: 3.6 MJ = 1 kW⋅h ≈ 1.34 hp⋅h. Since 1 J = 10 −6 MJ and 1 m 3 = 10 3 L, divide joule/m 3 by 10 9 to get MJ/L = GJ/m 3. Divide MJ/L by 3.6 to get kW⋅h/L.
The watt, kilogram, joule, and the second are part of the International System of Units (SI). The hour is not, though it is accepted for use with the SI.Since a watt equals one joule per second and because one hour equals 3600 seconds, one watt-hour per kilogram can be expressed in SI units as 3600 joules per kilogram.
A heat rate value of 2 kWh/kWh gives an efficiency factor of 50%. A heat rate value of 4 MJ/MJ gives an efficiency factor of 25%. For other units, make sure to use a corresponding conversion factor for the units. For example, if using Btu/kWh, use a conversion factor of 3,412 Btu per kWh to calculate the efficiency factor.