Solar Energy Types 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

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

Irradiance Visible light only F V = luminous flux of the source (lumens) E V = Illuminance of an object illuminated by F V at a distance d ( lm/m 2 = lux) E V = F V / 4  d 2 ex: 800 lumen bulb at 2 meters distance E V = (800 lm / 4  (2m) 2 = 16 lx All electromagnetic radiation: Visible efficacy of an Incandescent light:  =17 lm / W F R = Radiant Flux of the source ( W ) F R = F V /  E R = Irradiance of an object illuminated by F R at a distance d ( W/m 2 ) E R = F V / (4  d 2  ) = E V /  Example: An 800 lumen bulb at 2 meter distance E R = E V /  = 16 lx / 17 lm/W = 0.94 W/m 2

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

Part 2 Path of Sun: Seasonal & Daily

Effective Area

Insolation Rate Top of the atmosphere: Solar constant =1366 W/m 2 Peak Surface Insolation: Clear sky, summer, noon =1000 W/m 2 Average Surface Insolation: Clear sky, year round, all day = 250 W/m 2 Typical Insolation: Paso Robles, Average weather, all day avg Summer: 6 kWh / m 2 / day Winter: 3 kWh / m 2 / day

Part 3: Photovoltaics How Solar Cells work

Power & IV Curves

Maximum Power Point

Efficiency