An experimental study of the windmill of solar cell buckets

WREX 1996

AN

EXPERIMENTAL

STUDY OF THE WINDMILL OF SOLAR CELL BUCKETS Yoshihiro ONAI and Izumi USHIYAMA Ashikaga Institute of Technology 268-l Gmaecho, Ashikasga Cii, 326Japan

ABSTRACIIn order to demonstrate a complementary relationship between solar energy and wind energy, the authors proposed the WISH(Wiid and Solar Hybrid) type windmiU. The flexible amorphous photovoltaic modules are attached to the buckets of Savonius type windmill, After eight months operation of the WISH type windmiU in the field, we contirmed that there exists a complementary relationship between solar energy and wind energy. We also found that the power generation of this type of windmill was nearly twice as large as those without photovoltaic modules. KExwoRJls Savonius type windmill; Photovoltaic modules; Hybrid System Wmd Energy; Solar Energy, INTRODUCTION It is well known that solar energy and wind energy are the typical natural energy. Between these two energy sources may exist seasonal complementary relationship. Japan belongs to monsoon climate area therefore, the intensity of solar radiation is strong in summer and weak in winter. On the contrary, wind is strong in winter and weak in summer. Consequently, ifwe construct the generation system which comb&s these two energy sources, it is possible to acquire a stable energy throughout the year. The wind and solar hybrid systems currently in use consists of independent wind powered generators and photovoltaic modules. However, in this paper, the authors proposed an unique hybrid system which integrates the windmill and the photovoltaic modules. The windmiU celled Savonius type of which large buckets are attached by flexible amorphous photovoltaic modules. The system is named WISH: Wind and Solar Hybrid power system. The authors reported on the result of theoretical computation so far. (Morioka and Ushiyama, 1992) sYMBoJ..sANDuNrrs The main symbols and the units are as follows. A: swept area of the rotor [m’] OL: overlap ratio

H: rotor height [m]

D: rotor diameter [m]

GP: gap ratio

FXPERIMENTALAPPARATUSANDMETHOD The experimentalwidmili installed in the demonstration field is the Savonius rotor with two half cylinder section type. The configuration of the rotor is : rotor diameter D=O.67m rotor height H=1.4m, endplates diameter 0.80 and thickness of 6mrn respectively. Moreover, the swept area of the rotor A=0.94m2, gap ratio GP=QO7 and overleap ratio OL=O.52. The authors compared the ditTerence of generated output between the Savonius rotor generation systems with and without photovoltaic modules. (vshiyama and Nagai, 1988) 905

WREC 1996 The photovoltaic cell unit is flexible amorphous silicon solar module BC5422SO made by TDK corporation. Four sets of panels which consist of five sheets of above mentioned photovoltaic modules were attached to both sides of the windmill buckets. Figure 1 shows the schematic diagram of the author’s WISH type windmill

The specitication and the

characteristics of the flexible amorphous silicon solar module are shown in Fig. 2. The layout of experimental apparatus is shown in Fig. 3. The expetimental windmills were installed in the upper part of the concrete support of 5m height. The external appearance of the experimental windmills are shown in Photo. 1. The lower part of the windmills are connected with low-speed permanent magnet JX generator of 36W rated power through chain and sprocket of speed increasing ratio of 5. A slipring througb which to take out the electric power generated in photovoltaic modules is mounted on the top of the WISH type windmill. Moreover, as shown on Photo. 1, a Savonius type windmill without photovoltaic module on its buckets was also installed at the symmetrical posiion to the support The generation output by wind powered generators and photovoltaic module was charged into 12V storage battery At the same time, generated output by the wind powered generator and photovoltaic module is calculated through the operation of electric power unit, The measuring interval is 30 seconds. The data acquired were recorded into the personal computer through the datalogger at the measming room in the field. The anemometer and anemoscope were installed on the top of the support at 1Gmheight. The actinometer was mounted at the position of 2.7m height of the support.

_

630

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panel bucket(FRl’) waterproof film solar

Fig. 1 The schematic 560 /electrode(+)

\

electrode+)

electrode(-)

\

electrode(-)

/

I

of the WISH type windmill

seal film

\ cell

TypeBCS5422SO Operating voltage

17w

Operating current

3001~1

Open voltage Short-circuit

current

WV1 3SO[mA]

Characterllltlc value IP25°C. AM, 5.

,com,cnl at “ETaCal

Photo. 1 The external appeamnce ofthe acperimental

Fig. 2 The specification and the characteristics of the

windmill

flexible amorphous silicon solar module 906

WREC 1996

&Se Fig. 3 The layout of experimental apparatus Wind direction, wind speed and solar radiation are measured siiultaneously with the output of wind energy and solar energy These data are recorded into the same personal computer through the datalogger. The saved data in the hard disk are copied to a floppy disk, and the data are processed both daily and monthly at the laboratory. IXPEREVIENTAL

RESULTS AND CONSIDERATIONS

A relationship between the wind speed and the solar radiation is shown in Fig. 4. It is clear from the figure, from around 11 o’clock to around 16 o’clock, the wind speed is weak and the solar radiation is strong. On the contrary, t?om around 17 o’clock to around 24 o’clock, the wind speed is strong and the solar radiation is weak. Thus, there may exists a complementary relationship. As mentioned above, there exists a seasonal relationship between the solar energy and wind energy. As shown in this figure, there also exists daily complementary relationship between them. Figure 5 shows a cumulative daily output data in the second halfof June 1995.

I .2

I6

The generated output by the Savonius wind rotors with and without solar modules are nearly the same values.

14

-Wtnd

However, the total generated output by WISH type windmill is nearly twice as large as the Savonius type wind rotor without solar module. Thus, the effectiveness of the

sixed

- - 12

I Solar radlatlon

t

WISH type power system is confirmed. The monthly cumulative output of WISH type power system is shown in Fig. 6. It is obvious from this figure that, Tom June to September, the wind energy is strong as the characteristic of summer season in Japan. Then, from October to January, the solar intensity became weak while the wind energy became strong as the typical feature of winter

0.2

season in Japan. As previously described, these are the seasonal

complementary

relationships between

energy and solar energy. Consequently,

wind

it may be

0 0

2

4

6

8

concluded that the WISH type power system tested in this experiment

could

acquire

the

average

power

of

907

12

I4

I6

18

20 22 Ttme(hour)

Fig. 4 A relationship between the wind speed and the solar radiation

1kwhmonth through the year.

IO

WREC 1996

OSavonius

-y$100

-WISH

e 5

80

2 '; 60 Cl

tyoe windmill tyoe windmill (Wind energy)

--WISH

type windmill (Solar energy)

-WISH

tyoe windmill (Wind energy + Solar energy)

.+! 40 z Ig 20 0 0 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 TimeCday)

Fig. 5 A cumulative daily output data in the second half of June 1995 1600

?? Solar energy

T 1400

@IWind energy

;: 1200 E \ 1000 g 2 2

800

;

400

600

2 u' 200 n

”

June

July

August

September

October

November

December

January

Fig. 6 The monthly cumulative output of WISH type power system CONCLUSIONS After eight months operation of the WISH type power system in the field the following conclusions were drawn. (1) It was clear that there exists seasonal and daily complementary relationship between wind energy and solar energy (2) The power output ofthe WISH type wind rotor is much larger than that without photovoltaic modules. (3) The WISH type power system could acquire the stable energy from the wind and solar energy through the year. ACKNOWLEDGMENT The authors wish to express their gratitude to The R & D Center

staffof TDK corporation.

They kindly provided us the

flexible amorphous silicon solar modules in manufacturing our WISH type power system. REFERENCES S. Morioka and I. Ushiyanq (1992) A Wmdmill of Solar cell Blades, Proceeding of The 2nh World Renewable Energy Congress, Vol. 3, 1507. I. Ushiyama and H. Nagai, (1988) Optimum Design Configurations and Performance of Savonius Rotors, Wind Engineering, Vol. 12, No. 1, 59. 908