Tables B.1 and B.2 show the structure and functions for implementing the DISC (direct insolation simulation code) model in Excel®. Note the cell references rely on the exact structure of rows and columns shown. User values are entered in shaded cells.
TABLE B.1
User Location Input Parameters
|
Row |
Column A Label/Vali |
|
1 |
|
|
2 |
|
|
3 |
|
|
4 |
USER |
|
5 |
INPUTS |
|
6 |
Latitude |
|
7 |
User Value (+N, – S) |
|
8 |
Longitude |
|
9 |
User Value (+E, – W) |
|
10 |
Time Zone |
|
11 |
User Value (-W, +E) |
|
12 |
Stn. Pressure |
|
13 |
User Value mB |
|
14 |
Pstn/P0 |
|
15 |
= A13/1013.250 |
TABLE B.2
Functions to Be Entered in Row 2, from Columns G to W
|
Column |
Label (Row 1) |
Value or Function (Rows 2-8761) |
|
B |
Month |
1 to 12 |
|
C |
Day |
1 to 28, 30, or 31 |
|
D |
DOY |
1 to 365 |
|
E |
Hr |
1 to 23 |
|
F |
Obs. Hour |
1 to 8760 |
|
G |
ETR |
= 1370*(1.00011+0.034221*COS(H2)+0.00128*SIN(H2)+0.000719 *COS(2*H2) +0.000077*(SIN(2*H2))) |
|
H |
Day Angle |
= 6.283185*(D2-1)/365 |
|
I |
DEC |
= (0.006918-0.399912*C0S(H2)+0.070257*SIN(H2)-0.006758 *COS(2*H2) +0.000907*SIN(2*H2)-0.002697 *COS(3*H2)+0.00148 *SIN(3*H2))*(180/3.14159) |
|
J |
EQT |
= (0.000075+0.001868*C0S(H2)-0.032077*SIN(H2)-0.014615 *COS(2*H2)-0.040849*SIN(2*H2))*(229.18) |
|
K |
Hour Angle |
= 15*( E2-12.5+ J2/60 +(($A$9-$A$11*15)*4)/60) |
|
L |
Zenith Ang |
= ACOS(COS(I2/(180/3.14159))*COS($A$7/(180/3.14159)) *COS(K2/(180/3.14159))+SIN(I2/(180/3.14159)) *SIN($A$7/(180/3.14159))) *(180/3.14159) |
|
M |
Air Mass |
= IF(L2<89,$A$15*(1/(COS(L2/(180/3.14159)) +0.15/(93.885-L2)A1.253)),0) |
|
N |
Global Horizontal |
USER VALUE |
|
O |
Diffuse (optional) |
USER VALUE |
|
P |
Direct (Optional) |
USER VALUE |
|
Q |
Kt |
= IF(L2<80,N2/(COS(L2/(180/3.14159))*G2),0) |
|
R |
DISC Coeff. A |
= IF(Q2>0,IF(Q2>0.6, -5.743+21.77*Q2-27.49*Q2A2+11.56 *Q2A3, IF(Q2<0.6,0.512-1.56*Q2+2.286*Q2A2-2.222*Q2A3)),0) |
|
S |
DISC Coeff. B |
= IF(Q2>0,IF(Q2>0.6, 41.4-118.5*Q2+66.05*Q2A2+31.9 *Q2A3, IF(Q2<0.6,0.37+0.962*Q2,0)),0) |
|
T |
DISC Coeff. C |
= IF(Q2>0,IF(Q2>0.6, -47.01+184.2*Q2-222*Q2A2+73.81 *Q2A3, IF(Q2<0.6,-0.28+0.932*Q2-2.048*Q2A2,0)),0) |
|
U |
DKn |
= IF(Q2>0,(R2+S2*EXP(T2*M2))*$A$15,0) |
|
V |
Knc |
= IF(Q2>0,(0.886-0.122*M2+0.0121*(M2)A2-0.000653 *(M2)A3+0.000014*(M2)A4),0) |
|
W |
Model DNI |
= IF(Q2>0,G2*(V2-U2),0) |
Note: Columns B to F may use either specific, noncontinuous values or be filled as serially complete to the extent needed. Column N is the required user value for global horizontal total hemispherical irradiance.
