What is a megawatt and a megawatt-hour?
Megawatts measure instantaneous power; megawatt-hours measure total energy consumption over time. Understanding these units is essential for comparing solar proposals.
Megawatt (MW): A measurement of instantaneous power — how much power is being produced or consumed at a specific moment. One megawatt equals 1,000 kilowatts (kW) or 1,000,000 watts (W). A 1 MW solar array can produce up to 1 megawatt of power at any instant under peak conditions.
Megawatt-hour (MWh): A measurement of total energy consumed over time. One MWh is one hour of continuous consumption at 1,000 kilowatts. If a building uses 5 MW for two hours, that equals 10 MWh of energy.
Kilowatt-hour (kWh): The unit on your utility bill. One kWh is one hour of electricity use at 1,000 watts. Most buildings' consumption is measured in kWh.
Practical example: A typical large office building (100,000+ sq ft) uses about 20 kWh per square foot annually. A 100,000 sq ft building would consume 2,000 MWh per year, or roughly 5.5 MWh per day.
When evaluating solar proposals, vendors will quote annual energy production in MWh and cost per watt or per kWh. Understanding these units helps you compare bids accurately and assess whether a proposed system meets your building's energy needs.