الفهرس 
Solar energy
Direct coupled PV pumping systemOnly 14 pages are availabe for public view
 |  | from | 97 |  |  |
| | | from | 97 | | |
Abstract
At this study an evaluate the performances of a direct photovoltaic
pumping system based on an asynchronous motor driving a centrifugal pump.
The system was tested and evaluated while operating under Inshas climatic
conditions. Field experiments were conducted in the Farm of Soil and Water
Research Department, Nuclear Research Center, located at Inshas city,
Sharkia Governorate which represents sandy soil conditions, Atomic Energy
Authority, Egypt. The latitude and longitude of the experiment site are 30o
24` N, 31o 35` E, respectively, Egypt. Based on the results conclusions are as
follows:
• Solar radiation also differs according to seasons, in winter the sun
becomes lower in the sky and higher in summer because sun ray’s
angle changes due to the earth’s tilt angle.
• PV generator was tested under the Inshas desert climate. The
fluctuation of solar intensity and ambient temperature influenced the
generator output current and voltage respectively as mentioned by
the manufacturer. The day length and sun hours affected the total
daily power harvest through the months.
• Generated electric power was measured at different times during test
days starting 8:00 a.m. to 16:00 p.m.. The results show that
generated electric power increases with increasing solar radiation
intensity which means that generated electric power of PV module
depends on solar radiation intensity at different values ranged at 620
W/m2 in the morning and 438 W/m2 at afternoon and 1074 W/m2 at
midday.
• Variation solar radiation intensity affects in generated electric
power. The highest solar radiation intensity was obtained at midday
when sun ray is perpendicular on the surface.
• Module temperature was measured as a function of time during test
days starting 8:00 a.m. to 16:00 p.m. in months January, February,
March, April and May. (PV) performance decreases with the increase of module temperature. Module temperature and solar
radiation intensity play a big part in the photovoltaic conversion
process. the change of output voltage average for every module
temerature degree kelven was (-0.07%V/C) at 34.7ºC. On the
otherhand, it was (-0.24%V/C) at 43.8oC and it was (-0.36%V/C) at
51.8oC, while manufacturer it was (-0.35%V/C). The change of
generated electric power average for every module temerature
degree kelven was (-0.27%W/K) module temperature at 34.7ºC. On
the otherhand, it was (-0.27%W/K) at 43.8oC and it was
(-0.40%W/K) at 51.8oC, while manufacturer mentioned that it was
(-0.45%W/C).
• Module efficiency indicate graduate increase with increase solar
radiation intensity. Module efficiency average values reached to be
14.70% at 12:00 p.m. when the average of solar radiation reaches to
be 1074 W/m2 at midday for months March, April and May for
months March, April and May.
• The increase of hydraulic power as a result of the increasing in solar
radiation intensity for months March, April and May. Hydraulic
power average values reached to be 161W at 12:00 p.m. when the
average of solar radiation reaches to be 1074 W/m2 at midday for
months March, April and May.
• Pumping system efficiency indicate graduate increase with increase
solar radiation intensity. Pumping system efficiency average values
reached to be 22.97% at 12:00 p.m. when the average of solar
radiation reaches to be 1074 W/m2 at midday for months March,
April and May. for months March, April and May.
• Overall system efficiency indicate graduate increase with increase
solar radiation intensity. Variations in the solar radiation intensity
change the overall efficiency. Overall system efficiency average
values reached to be 3.38% at 12:00 p.m. when the average of solar
radiation reaches to be 1074 W/m2 at midday for months March,
April and May. for months March, April and May.from the obtained results, it can be evaluated the performances of a
direct photovoltaic pumping system based on an asynchronous motor driving
a centrifugal pump and it should be increase during the summer season. It
was also found that the lowest overall system efficiency of the solar pumping
system reached to be (2.92%) while the highest overall system efficiency of
the solar pumping system reached to be (3.93%) at 12:00 p.m. for May.
So it should be recommending the followings:
1. This study recommended a strong way such as solar powered
pumping system for small scale areas suitable as an alternative to
fossil traditional fuels.
2. Considering reduction of power output from the grid system leads to
increase the demand for the solar generators to compensate.
3. Economically, its recommended to use solar generators instead of
diesel one for remote areas. and the study showed a lot of benefits for
using renewable energies.
4. Using soil moisture measurement can help to predict the actual water
movement in soil.
5. Matching system components and using high efficient parts will help
to maximize overall system efficiencies.