1. The wind is blowing on a turbine 10 feet in diameter at a velocity of 12 mph. What is the power developed by the turbine? Power = 0.5 x Swept Area x Air Density x Velocity 3 Air density =1.23 k g/m 3 Power = 0.5 x 32.96x 1.23x 5,36 3 = 3121 W Solution;

2. 2. It is desired to obtain 25 kW of AC out of a solar array at 120 VAC, pf = 1. The inverter has an efficiency of 85% and requires 50 VDC to operate. Solar cells are available that provide a voltage output of 0.5 V at 3 A. A How many solar cells are required with a 20% safety factor? Describe the connection diagram of the solar panel array. It is not necessary to draw it. Solution: I = 25kW/120V = 208.33 A With a 30E% safety factor, I = 208.33*1.2 = 250 A This will require 250/3 = 83.33 = 84 rows (no partial rows. In series, 50/0.5 = 100 solar cells are required.

3. Therefore, a total of 100 x 84 = 8400 solar cells are required. Allowing for the 85% efficiency of the inverter, 84/.85 = 98.8 = 99 rows are required and 100 in series are still required. Therefore, 100 X 99 = 9900 solar cells are required, 99 rows in parallel and 100 solar cells in series The approximate cost is $625