solar

Question 1

Average extra terrestrial flux from the sun

Answer 1

1353 W/m^2

Question 2

Where does the sun lose energy as it moves through the earths surface.

Answer 2

• Convection currents (Wind and ocean waves)
• Evaporation of water and heating
• Photosynthesis on land and sea
• Formation of fossil fuels
• Tidal energy
• Geothermal energy
• Direct transfer to heat

Question 3

Calculating Solar Resource. Write down the symbol for each parameter.
- Latitude
-Longitude
- solar declination
- Solar time
- solar altitude
- solar azimuth
- surface orientation
- surface tilt
- surroundings
- Direct irradiance
-Diffuse iradience
- global irradiance
- sky diffuse
- Angle of incidence
-Ground reflectivity

Answer 3

• Latitude = L
  -Longitude =
• solar declination
• Solar time
• solar altitude - bs
• solar azimuth - w = mag (surface azimuth - solar azimuth)
• surface inclination - bf
• surface tilt
• surroundings
• Direct irradiance - Idh
• Diffuse irradiance - Ifh
• global irradiance - Igh
• sky diffuse -Ish
• angle of incidence - ib
• Ground reflectivity -rg

Question 4

formula for w

Answer 4

mag(surface azimuth -

Question 5

Formula for PV power output

Answer 5

P = (0.13)IT

Question 6

Direct Irradiance formula at an inclination angle

Answer 6

Id(angle) - Idh * cos(ib)/sin(Bs)

Question 7

Reflected irradiance formula if at an inclination angle

Answer 7

Ir(angle) = 0.5(1- cos(90-bf)(Idh+Ifh)*rg

Question 8

Total irradiance formula

Answer 8

IT = Direct + reflected+Sky diffuse

Question 9

What is used to measure direct irradiance on a surface

Answer 9

Pyranometer

Question 10

What measures direct beam solar irradiance by tracking the suns position

Answer 10

Pyrheliometer

Question 11

Formula for solar time and what each parameter is

Answer 11

ts = (Ldiff/15) + (et/60) +ds

• Ldiff = Longitude difference (W-ve,E+ve)
• tm = local time (hrs)
• et = eqution of time
  ds = daylight saving time

Question 12

formula for hour angle

Answer 12

Thetah = 15*(ts-12)

Question 13

When is the large sky diffuse formula used?

Answer 13

To represent a non ideal sky that is not isotropic

Question 14

How does a photoelectric (PV) panel work

Answer 14

Converts solar radiation to electricity via the photoelectric effect. A photon strikes an electron in a semiconductor material which releases an electron that flows into a separate circuit.

Question 15

Formula for calculating energy of a photon

Answer 15

E = hv

Question 16

What is a common material used in PV cells and why

Answer 16

Silicon and boron are commonly used as silicon has no extra space in its outer shell whereas boron has a single space for an oncoming electron to attach to. Creates a p-n junction. Electrons are pulled from the n-side to the p-side.

Question 17

What equation describes PV panel performance

Answer 17

Pmp = Pstc (itot/1000)(1-b[T-25])*p

where:
Pmp = Power(W)
Pstc = Power at test conditions
Itot = Total incident solar
b = loss coefficient
T = operating temp (degrees)
p = number of panels

Question 18

What formula describes the sky diffuse component if the sky is completely overcast (isotropic sky).

Answer 18

If(angle) = Ifb(0.5(1+cos(90-bf))