A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...

A = +0.004013327
B = +0.06476916
C = -0.66956539
D = +0.019276169
E = -0.00051297
Ads is multiplied by the relative atmospheric pressure (PRES or DPRES,
Namelist BASIC) to account for the effect of altitude. It is the apparent sun an-
gle, not the actual sun angle, that is tracked by the heliostats.
The default latitude is that for Barstow, CA:
X(PLAT) = 35.0'.
II1.B-2. Insolation-The extraterrestrial insolation of the sun, SO, including
the effect of eccentricity of the earth's orbit, is given by (Reference 19):
SO (kw/m2) = 1.353 + 0.045 cos (27r DAY 365.0 + 10.0 1 (1II.B - 7)
where DAY = day of the year.
The position of the sun is symmetric about the summer and winter solstices.
The code ignores the small change in declination during each day and assumes
that sun position is symmetric about noon.
DELSOL assumes clear sky models to predict the direct normal insolation,
S, at the earth's surface. The parameter INSOL controls the insolation model
choice. Insolation is decreased by transmission through the atmosphere. Losses
depend on such factors as the weather, air mass traversed, and altitude, which de-
termine the extent of photon absorption and scattering. The result is that part
of the direct insolation is converted to a diffuse form which cannot be concen-
trated by the heliostats. The annual energy predicted by the clear sky models is
corrected for weather effects as described below.
These insolation models are analytical approximations to a widely varying ac-
tual insolation value. That is, measured data for a specific location and time may
not agree with the results of any insolation model. For a performance calculation,
the user should choose a model which, when incorporated with weather consid-
erations, will predict the closest insolation to measured values. For optimization
(design point) calculations and for flux map calculations on optimized systems,
the value REFSOL (Namelist BASIC) is used as a fixed insolation value.
a) INSOL = 0, Meinel Model (Reference 20)
S = So{ (1.0 - 0.14ALT)exp(-0.357(sec19~)~~~'*) + O.14ALT) (1II.B - 8)
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