Before looking into solar, it’s helpful to understand what a kilowatt (KW) and a kilowatt-hour (kWh) are. The solar industry will use these figures to plan what system size your home will need. This can be confusing and easy to mix up. The difference between KW and kWh can be explained using this analogy:
A mile is a unit of distance, mph is the measurement of distance covered over time. A kilowatt is a unit of energy and a kWh is a measurement of energy consumed over a period of time.
What Is a Kilowatt Hour And How Much Does It Take to Power A House?
When you are trying to figure out how many solar panels to install on a home, the first place to start is seeing how many kilowatt hours a year the home uses. A kilowatt-hour, or kWh, is a unit of measurement that is used to track your home’s electrical usage.
For example, Let’s look at a 3,000-watt oven used for one hour a day and calculate what that usage is per month:
- Calculate the KW by dividing the wattage by 1,000: 3000 watts/1,000 = 3 KW
- Get the daily use by multiplying the KW with hours a day: 3 kW X 1 hour = 3 kWh per day
- Multiply that usage by 30 or 31 to get the monthly kWh usage: 3 kWh X 30 days = 90 kWh per month
To find the monthly kWh usage you would use this formula for every appliance in your house that uses electricity like your refrigerator, microwave, washer and dryer, AC unit, heater, etc.
How Many Kilowatts Does It Take to Power a House?
With the average American home consuming 900 kWh a month or 30 kWh a day, that brings the total yearly usage to around 10,800 kWh. This means that most solar energy systems will need to be large enough to produce this many kWh’s in a given year.
Each home is going to require different amounts of solar panels to get to this level of production. A home in Los Angeles with a fairly south-facing roof might only need 15 panels to produce enough energy, whereas a Lake Tahoe cabin with some shading could need as many as 25 if you are using a 400-watt panel.
Even though there can be a wide disparity in the sizing of the system depending on your home and usage, the good news is that in most cases you will save money on your monthly electric cost. You can learn more about the cost of solar or contact our team about solar panel installation options.