Simple Wind Turbine Investment Payback Calculator

Answer the questions below. See notes for additional explanation

Enter the rated capacity of the wind turbine in kilowatts (kW). This cannot be any larger than 25 kW for residential units and 200 kW for commercial units, and in no event larger than the actual customer load.
Enter the capacity factor. Capacity factor is the fractional percent of the energy that would be produced if the wind turbine operated 24 hours per day for an entire year. A realistic range is 0.20 to 0.35.
Choose Residential or Commercial Application:
Enter the total estimated cost of the turbine, tower, foundation, installation, disconnect switch, electric wiring, protective devices, etc., less any tax credits or grants.

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.