How Many Solar Panels Do You Need to Power Your Home?
Imagine that you’re trying to determine how many candles it would
take to boil a cup of water in a pan. To come to an accurate total,
you would need to answer several questions. What type of pan is it?
Cast iron? Stainless steel? What is the size of the pan? Before
being able to accurately predict how many solar panels you need to
power your home, several factors need to be taken into
consideration.
The first step is to assess your current electrical needs. Your
total electricity usage is measured by the kilowatt-hours (kWh) your
home uses in a 12-month period. A solar power installer can help you
look at past electric bills. The goal is to establish not only how
much power your home uses, but what percentage of your electrical
needs you would like to be met with solar power.
To get pricing on a solar installation in your area, click here.
Some cities, like New York and San Francisco, have online
interactive maps to help with estimating the size and cost of solar
power systems. Users simply enter their address. Some solar
providers utilize specialized software that enables them to give
offsite estimates, usually emailed within 24 hours, in response to
online requests for a quote.
How Many Solar Panels Do I Need?
Once you have established the number of watts that you would like
your solar panels to provide, several other factors must be
considered to determine the size of the system, including the amount
of sunlight available in your home’s location and the orientation of
your home’s roof to the sun.
Solar modules are categorized by their efficiency, or rated power
output, a measurement of the peak power each panel can produce. When
estimating how many panels you need to power a home, solar
contractors will calculate the roof area needed in square feet.
For example, to generate 2,000 watts from a 12%-efficient system,
you need 200 square feet of roof area. The cost of a solar system,
including the panels, equipment and installation, is usually
described in dollars per watt. While rates vary according to
location, a typical system costs $7-10/watt. For the 200-square-feet
example used here, the cost of the system would be $14,000 to
$20,000.
However, with state and local solar rebates, net metering and
federal tax incentives, the cost of installation can be
significantly reduced—sometimes even cut in half. The federal tax
credit program, for example, can cover up to 30% of the cost. In
addition, solar contractors now offer financing options, including
solar leases with zero down, with monthly payments that are
typically less than homeowners were paying on monthly electrical
bills.
Today, the average cost for a 10-panel solar power system is
$11,000. According to JEA, a community-owned electric utility in
Florida that serves 417,000 customers, the average solar panel
system saves homeowners 30% on their electric bill. Savings for some
customers are much higher, with some home systems producing more
electricity than the home uses. That electricity is typically sold
back to the grid, providing extra income to homeowners.
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