Solar EnergyTypes of Generators

Irradiance

Insolation

How Solar Cells work

Topics Part 1

Types of Solar Power Generators Irradiance Inverse Square Law

Part 2 Path of Sun: Seasonal and daily Effective cross section Insolation Rate

Part 3 How Solar Cells work Power & IV Curves Maximum Power Point Efficiency

Part 1:Types of Solar Power Generators

Passive Solar heat collectors Rooftop solar water heaters

Solar heat collectors – Steam Turbines Parabolic Troughs Thermal Towers Other Solar Concentrators

Photovoltaic Panels Silicon, crystalline, thin film, organic dyes

Solar Water Heaters

Solar-Steam Generators

Solar-Steam Generators

Parabolic Trough

Ausra: 177 MW

Carizzo Plain

Thermal Tower

Mojave

Other Solar Concentrators

Photovoltaics

PG&E Carizzo Plain

Topaz 550 MW & High Plains Ranch 250 MW

CalExpo Solar Park

IrradianceVisible light only

FV = luminous flux of the source (lumens)

EV = Illuminance of an object illuminated by FV at a distance d ( lm/m2 = lux)

EV = FV / 4d2

ex: 800 lumen bulb at 2 meters distance EV = (800 lm / 4(2m)2 = 16 lx

All electromagnetic radiation:

Visible efficacy of an Incandescent light: =17 lm / W

FR = Radiant Flux of the source ( W ) FR = FV /

ER = Irradiance of an object illuminated by FR at a distance d ( W/m2 )

ER = FV / (4d2 ) = EV /

Example:

An 800 lumen bulb at 2 meter distance

ER = EV / = 16 lx / 17 lm/W = 0.94 W/m2

Inverse Square Law

2

2

1

2

2

1

d

dEE

Irradiance (E) is inversely proportional to the square of the distance (d) from the source

Part 2Path of Sun:Seasonal & Daily

Effective Area

Insolation RateTop of the atmosphere:

Solar constant =1366 W/m2

Peak Surface Insolation:

Clear sky, summer, noon =1000 W/m2

Average Surface Insolation:

Clear sky, year round, all day = 250 W/m2

Typical Insolation:

Paso Robles, Average weather, all day avg

Summer: 6 kWh / m2 / day

Winter: 3 kWh / m2 / day

Part 3:PhotovoltaicsHow Solar Cells work

Power & IV Curves

Maximum Power Point

Efficiency