Environmental Engineering Reference
In-Depth Information
Table 6.1. Simulated electric consumption needs for the proposed sports hall building. Re-
sults obtained using the EnergyPlus software
Total electric energy demand in
kWh
Nr. of
days
Daily average in
kWh/day
January
4529
31
146.1
February
3867
28
138.1
March
3898
31
125.7
April
2763
30
92.1
May
1999
31
64.5
June
2258
30
75.3
July
2388
31
77.0
August
2410
31
77.7
September
1789
30
59.6
October
2192
31
70.7
November
2328
30
77.6
December
2835
31
91.5
Annual Sum
33255
365
-
Average
2771
-
91.1
The lower buttons of this second screen allow the results of solar radiation
throughout the year to be obtained, either graphically (only the monthly day aver-
ages) or in a table format (monthly day and hour average values). In practice, PV
panels are always tilted a minimum angle towards the Equator (usually > 5º), to
improve efficiency and to allow that the rain cleans their surface. Unless the solar
modules are integrated or mounted directly on the roof, it is recommendable to
consider the tilting of the modules to achieve their maximum output: the theoreti-
cal optimal tilt angle is one corresponding to the latitude of the absolute geo-
graphical coordinates of the design location, with an approximate variation of
±15º for winter and summer optimization; in our case Florianópolis has a latitude
position 27º S (below the Tropic of Capricorn), therefore we should incline the so-
lar modules an angle between 12º and 42º towards North. Using the software Ra-
diasol, we find that the tilt angle for which the average annual solar irradiation on
the plane of array is maximized is either 18º or 19º; as the higher the angle the
more interspacing will be required to avoid shading, we will choose 18º. To sum-
marise, the monthly values of average radiation to be used for Florianópolis with a
panel inclination of 18º to the North are as shown in Table 6.2 .
Table 6.2. Average daily irradiation (in kWh/m 2 *day) by month according to Radiasol
(Florianópolis, tilt 18ºN)
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Aver.
5.79 5.32 5.21 4.64 4.08 3.59 3.69 4.37 4.24 4.83
5.37 6.02 4.76
The values shown above are the estimated daily averages of daily irradiation for
every month of the year at the geographical location and panel orientation indi-
cated. We can observe that the variation around the mean (4.76 kWh/m 2 *day)
 
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