|
|
Windturbine and Solar Cellfor Home |
In December 2001, Mr. Greenwood found a set of windturbine and solar cell for home is marketed in a house exhibition center near his home. A small venture company called Zephyr developed it. a small windturbine generates 400w power at wind speed of 12.4m/s. A solar panel generate 22w. Complete set including battery, inverter, controller and automatic switch to commercial power grid cost 300,000 yen.
He saw many windturbines having the same design in front of a hut near peak of Mt. Senjyou-dake, in Itoh Marina and in Kamakura . Apparently, it looks as though they were supplied by the same company. He was fascinated and determined to have one in the near future in his garden.
 AC Generator |
 Rectifier |
inside generator housing
In June 2003, Mr. Greenwood made a purchase order for advanced model of the same system. Advanced model has power assist module which rotate blade 6 second in every 1 minutes to catch light wind. Thus a chance of catching wind improves. Due to this additional capability and bigger solar panel and battery capacity, cost was doubled. But it is workable system.
 Windturbine before setup |
 Solar Cell and Turbine Blade |
 Control Box installed in the garage |
 Battery installed in the garage |
Normally, cumulated power is used for dedicated user such as exterior garden lamp. But in case of shortage of battery power, automatic switch is provided for switching over to commercial power.
Within a few days after receipt of the assembly unit, Mr. Greenwood completed installation and started operation without power output. Due to wrong signal cable, he couldn't start operation of DC to AC inverter until he received right cable. Following video is a windturbine in operation.
Normally, existing garage lamp will use power generated at home. Although the power cost reaches almost $5 per kWh, it will help as emergency power supply in case when commercial power supply was topped.
Photo sensor switch |
Garage Lamp |
LED lamp
Performance
Observed average daily generation of 420 kWh is a bit smaller than catalogue figure of 570Wh/day. This is mainly caused by bad location of windturbine. Please refer Cost of Various Solar Power.
| Items | Unit | Figures |
| Annual power generation by windturbine(100W x 8h/d x 36d/year) | kWh/year | 28.8 |
| Annual power generation by solar cell (Time averaged emmision/AM1.5 emission=11.4%) | kWh/year | 124.7 |
| Annual total power generation | kWh/year | 153.5 |
| Average daily generation | kWh/d | 420 |
| 13Wx12h/d lamp consumption over 330days | kWh/year | 51.5 |
| 11.6W standby power of controller and sensor switch of | kWh/year | 102 |
| Initial investment | yen | 710,000 |
| Annual net-cash flow/initial investment | %/year | 11.18 |
| Power unit cost | yen/kWh | 517 |
Further analysis using Betz's equation revealed that overall conversion efficiency of the windturbine generator is 56%. If we assume turbine blade efficiency h of 70%, overall eficiency of high frequency AC generator-DC rectifier set becomes 80%.
P=(8/27)*p*r2*r*u3*h (kg-m/sec)
where,
Air Dencity r at 25 deg.C=1.286 (kg/m3)
A Gravity aceleration: gc=9.81 (m/sec2)
Blade Radius: r (m)
Wind Velocity: u (m/sec)
Turbine Generator Overall Efficiency: h (-)
Betz Parameter: 16/27=0.593
In April 24, 2004, this windturbine was reported in Japn's largest news peper "Yomiuri"
2001/12/23
Rev. May 28, 2010
