ZEMCH 2015 - International Conference Proceedings | Page 569

Results and Discussions
The measurement data obtained covered hourly irradiance for 365 days in 2009. (Fig. 3) shows a
typical hourly variation of irradiance throughout the day on July 2009. In the figure, solar irradiance was measureable as early as 4.00 am during sunrise, which occurred early in summer time.
The measured irradiation increased at about 240 kW/m² per hour. The peak irradiation, of 1171 kW/
m², was reached at 10.00 am. After 12 noon, the irradiation decreased at a rate of about 250kW/m²
per hour. The irradiation diminished after sunset at about 5.00 pm. In general, there was about
continuous 7 hours of irradiation that exceeded 800 kW/m² on that day, which could be regarded
the ratio of surface reflection to solar incidence, could be determined from the measurement
system. It was reported in an earlier work (Bou-Rabee 2015).
1,200

Daily Irradiance, kWh/m²

1,000
800
600
400
200
0
0

4

8

12

16

20

24

Time (hour)

Figure 3. Typical hourly variation of irradiation throughout the day on July 2009
Shown in (Fig. 4) is comparison of the average hourly variations of irradiation for January, April,
July and October. It is clearly shown that the highest irradiation occurred in July and the lowest
being in January (winter). In April and October, the amounts of irradiation are shown to be identical. However, the level is slightly higher in April despite the large fluctuations, as elaborated,
suggested to be caused by sand storm as suggested by a meteorological report (Kuwait Institute
of Scientific Research 2012). Noting that the amount of energy received through sun irradiation is
the area under the curve, it is clear from (Fig. 4) that the most energy available is in the summer
and vice versa during the winter.
1200

January
April
July
October

Irradiation (W/ m²)

1000
800
600
400
200
0

4

6

8

10

12

14

16

Time

Figure 4. Comparison of average hourly variations of irradiation for January, April, July and October
It is interesting to note that the distribution in (Fig. 5) is not symmetrical, for which greater amount
of irradiation is displayed during the first half of the year as compared to the second half.

Integration of solar energy systems to reduce environmental impacts in Kuwait

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