Solar Flashcards
State the range of frequencies in the solar spectrum
0.29 micrometres in the ultraviolet region to 0.4-0.8 micrometres in the visible region and 3.2 micrometres in the infrared region.
The diagram showing the building solar interaction has list of qualities from A-I, describe them.
A- reflected short wave flux
B- flux emission
C- short wave flux transmission causing opaque surface insolation.
D- short wave transmission causing transparent surface insolation.
E- short wave transmission to adjacent surface
F- enclosure reflections
G- short wave loss
H- solar energy penetration by transient conduction.
I- solar energy absorption prior to re-transmission by B.
How is the position of the sun described and what do these qualities depend on?
Altitude and azimuth angles which depend on site latitude, solar declination and local solar time.
State the formula to determine solar declination
d=23.45sin(280.1+0.9863Y) where Y is the year day number.
State formula for hour angle
Theta=15(12-Ts)
Ts = local apparent time.
State the formula for changing solar time to local mean time.
Ts-Tm=(+/- 4*L+et)/60+d
Where: L is the longitudinal difference, et is the equation of time (mins) and d is the possible correction for daylight savings
What is the longitude difference?
The difference between the observers actual longitude and longitude of mean for local timezone. Difference is negative for Western locations and positive for Eastern location.
State the equation for solar azimuth.
as = sin^-1(cos(d)*sin(theta)/cos(Bs))
State equation for surface solar azimuth.
w=abs(as-af)
w = surface solar azimuth, as = solar azimuth, af= surface azimuth
What are the three components of total radiation incident on a surface?
Direct, surroundings reflected and sky diffuse.
What is the formula for direct irradiance?
dB=dh*cos(iB)/sin(Bs)
IdB= direct intensity
Idh = direct horizontal
When the sky is completely overcast, what is the isotropic formula for the sky diffuse component of radiation?
Isb=ifh[0.5*(1+cos(90-Bf))]
