How to Measure the Payback Period of Solar Power

One of the discussions I have with homeowners whocomes in from your utility company. All this is explained
are considering investing in a solar power system forat my website, This averages out to 600 KWh of
their home is about how long the payback period is.power per month. At 16 cents per KWh, you would
We hear this term used with almost any cost-savingspend $96 per month on electricity. This is your current
product, including hybrid cars. With solar power, thecost. To get an idea of what a Kilo Watt hour is, if you
payback can be from Day 1, depending one ahave a 100 Watt light bulb burning for one hour, you
combination of the price you pay for electricity and thehave consumed 1 KWh, which cost you 16 cents.
interest rate you pay to finance your solar powerWith this sample system, theoretically you are now
equipment. In this article, I will show you how you canproducing all the power you need from your solar
determine your payback period.system. During the day, your system will be producing
Solar power is at an opportune time in this country, andmore power than you are consuming, and the extra
especially in states such as Pennsylvania and Newpower is sold back to your utility at the same price you
Jersey, where state and utility rebates can offsetare paying (your meter actually runs backwards). At
most of the cost. In Pennsylvania, the state is currentlynight, you pull power back from "the grid". Over the
rebating $2.25 for each watt of DC power that yourcourse of the year, you essentially have produced an
system produces. Thus, if you purchase a system withamount of power equal to what you consume with
30 panels, each rated at 200 Watts, you arethis example system.
purchasing 6,000 Watts of DC power. Thus, youNext, lets look at the financing side of the equation. If
would get a rebate of $13,500 from the State. Theyou use your home equity to finance the $24,150 for
average cost of a solar power system is about $7 to15 years at 6% interest, your monthly payment would
$8 per DC Watt. The price varies depending on thebe $204. So far, you have not achieved any instant
company that makes and installs the system. Using thepayback, as you are spending $108 per month more
high end, this example system would cost $48,000.than you are saving in electricity costs. However, the
Once you subtract the state rebate, you are left withstate of PA also mandates that the utility pay you
a cost of $34,500. Next, the IRS lets you take a 30%back for generating power, even if you are consuming
tax credit against this difference. Thus, when you doit. For every 1,000 KWh you produce, you get a
your taxes, you get back $10,350, bringing your costcertificate that gets traded back to the power
down to $24,150. This is the amount you need tocompany for about $240. Thus, this sample system
finance with long term financing.earns 7 certificates, for a rebate of $1,680 per year
Lets assume that you live in the Philadelphia area,(for every year), or $140 per month. Now, add your
which includes all of the Delaware Valley, in the$96 per month in electric bills you are not paying, and
counties of Bucks, Montgomery, Philadelphia, Chesteryou are saving $236 per month. Since your loan
and Delaware. The average cost of electricity frompayment is only $204 per month (with interest that is
PECO is about 16 cents per KWH. Based on industrytax-deductible if financed with a home equity loan), you
standard calculations that show how many Kilo Wattsare saving $34 per month, from Day 1! Now, as the
on average a solar power system will produce overcost of electricity continues to increase, your savings
the year, this 6,000 Watt system (DC capacity) willwill continue to grow.
produce 7,200 KWh of AC power, which is what