Energy, and electricity in particular, has several different units of measurement that can be more than a little difficult to understand. Here is an easy-to-understand primer. Electricity has three basic units of measurement:
- Voltage, measured in volts
- Current, measured in amps
- Resistance, measured in ohms
A good way to understand these units is to think of a hose. The voltage is equivalent to the water pressure; the current is equivalent to rate of flow; and the resistance can be compared to the hose diameter.
Power is the rate at which energy is generated and consumed and is measured in watts. Watts are the product of Voltage (volts) and Current (amps).
1,000 watts is one kilowatt, and 1 million watts is a megawatt. California currently has 500 megawatts of solar power spread over 50,000 solar installations.
A watt-hour is equal to the work done by one watt acting for one hour. For example, a 100 W light bulb that is on for one hour uses 100 watt-hours (or 0.1 kilowatt hours). Your energy utility measures your use in kilowatt-hours.
One last term that is useful to know is “load.” A “load” is anything on the electrical circuit that draws power. Your refrigerator, TV, and electric toothbrush are all examples of loads.