Simple Wind Turbine Investment Payback Calculator
Enter values in yellow cells (see notes for additional explanation):
Note 1: The minimum value assumes that 100% of the electricity
generated is sold to Midwest Energy at the average buyback rate paid for the 12
months ended August 2008 of $0.051923 per kWh. The maximum value assumes that 100%
of the electricity generated is used on-site. For Residential rate schedules, the
maximum value of wind energy is derived using the sum of the middle block value
of M System Schedule RS winter energy rates of $.085291 plus an estimated ECA of
$0.01 per kWh. For Commercial rate schedules, the maximum value of wind energy is
derived using the sum of the middle block value of M System Schedule GSM winter
energy rates of $.059342 plus an estimated ECA of $0.01 per kWh. Midwest Energy’s
rates for other customer classes and seasons differ somewhat from the numbers used
here. However, the variances caused by estimating the annual capacity factor and
estimating the percentage of wind energy sold back to Midwest Energy lessen the
importance of using the exact rate in this estimation process.
Note 2: Includes items such as maintenance, property tax, insurance,
etc. According to a study published at www.windpower.org, the average annual maintenance
cost for a 25-150 kW wind turbine is $.01 per kWh. This is a reasonable rule of
thumb to follow for estimating annual costs if they are initially unknown.
Note 3: This payback calculator includes two assumptions to simplify
calculations. First, it assumes flat retail and buyback rates. Rates will increase
over time, so that will shorten the payback period compared to this calculation.
Second, this calculator ignores the owner’s borrowing costs. If borrowing costs
were included, the payback period would be longer than is calculated here.