Electricity basics for solar homeowners

April 9, 2021 | 3min read

Ever wondered how much electricity a kilowatt-hour is? What about the difference between the 120-volt system used in your home versus the 220-volt system? Or why you can’t draw power from your system during a blackout? This article will cover the electricity basics for solar homeowners.

Electricity basics: What is a kilowatt-hour?

A kilowatt-hour is 1,000 watts of electricity delivered in one hour. Electricity usage is measured in kilowatt-hours, so if you know how many watts of electricity an appliance uses, you can estimate how much it will cost you to run that appliance using this formula:

kilowatt-hours = (watts x hours) divided by 1,000. Then, multiply the kilowatt-hours you get by the price, in kilowatt-hours that the electric company is charging you.

For example, if you have a 100-watt lightbulb and you run it for one hour. 

(100 watts x 1 hour) divided by 1,000 = 0.1 kilowatt-hours.

If the electric company charges you $0.20: 0.1 kilowatt-hours x $0.20 = $0.02.

It would cost you two cents to run that 100-watt bulb for one hour.

What’s the difference between 120 volts and 220 volts?

Homes are wired to provide both 120 Volts AC and 220 Volts AC power. What’s the difference, besides the voltage, between these two types of electrical current? When electricity is provided to your home from the utility company or from a home solar system, it comes in the form of split-phase240 Volts AC current. A split-phase electrical current is composed of two electrical currents that are 180 degrees out of phase with each other. 

In a home, one phase goes from zero Volts to positive 120 Volts. The other phase goes from zero Volts to negative 120 Volts. Your appliances that run 220 Volt power use both of these phases, from 120 Volts positive, through zero Volts, to 120 Volts negative. Add both of those, and you get 240 Volts. Your appliances are rated to use 220 Volts because there is some loss in the wiring that feeds power to them. The 120 Volt circuit in your house is simply one-half of that split-phase 240 Volt current.

Why can’t you draw power from your solar system in a blackout?

There are two reasons for this actually, the first reason is that your solar system is designed to isolate itself from the electrical grid in the event of a blackout. This is done to prevent electricity from being fed into the grid while utility crews are working on it. The second reason is that your solar system’s inverter depends on a stabilization signal provided by the grid. That signal keeps the voltage that your solar system is providing at the proper level for use in your home. During a blackout, that stabilization signal is lost, so your inverter has to shut down.

Solar systems with batteries can generate and provide their own stabilization signal. That allows the inverter to keep running. Since the inverter keeps running, your solar panels continue to provide electricity that your system can then use power to your home and charge your batteries.

Electricity basics: How does a solar system distribute electricity?

During the day, when your solar system is producing electricity, your home gets priority. This means your system will make sure it fully powers your home before it sends any electricity to the grid. If you have home batteries, your solar system will give them priority over the grid. This helps to ensure that they get fully charged.

Freedom Forever enables you to go solar with confidence

There are a lot of things to consider when installing a solar power system. You need to make sure you get the right-sized system to provide power for your home, and if your utility company offers net metering, you want your system to provide enough excess power to the grid to cover your electricity usage in the evenings and at night when your system isn’t providing power. There are also home batteries to consider, are batteries right for your home? Freedom Forever’s family of independent authorized dealers can answer your questions and they will help you get the right size solar system for your home. Once you go solar with us, you can enjoy Freedom’s 25-year Production Guarantee

Ready to go solar? Call us at 800-685-1850 or click below to get started