Solar Energy

Solar Energy

The Sun

• 99.98 % of enegy from the sun

• 1/3 of the tide and flood caused by the sun’s gravitation

• Distance: 150 million kilometers

The Sun

• 99,9 % of the mass of the solar system(1,989 x 1030 kg)

• Temperature at the centre: 14,8 million K

• Surface temperature: 5.800 K

• 73,5 % Hidrogen, 25 % Helium

• Gravity 27 times higher than on earth

• Ca. 4,5 billion years old

Energy generation in the Sun

• Mainly proton-proton reaction

• 564 mio t of hidrogen are burned to 560 mio t of Helium

• Output power:3,7 x 1026 W

• E=mc2

Structure of the Sun

• Structure– Core– Radiation zone– Convection zone– Photosphere– Chromosphere– Corona

Lifecycle

• 4,6 billions years ago: gravitational collaps• Today: main sequence evolution (halfway in ca.

10 billion years of H to He fusion)• In 0,9 billion years: earth temperature > 30°C• In 1,9 million years:earth temperature > 100°C• in 7 billion years: red giant, venus and mercury

destroyed, earth surface molten• He to C fusion starts (ca 130 million years)• White dwarf (only 50 % of its original mass)

Solar spectrum

• Solar constant (AM 0): 1354 W/m2

• AM 1: 1040 W/m2

• AM 1,5: 970 W/m2

Solar energy harvesting

• Photovoltaic or Photothermal

Solar thermal energy harvesting

Solar thermal energy harnessing

Active:- Heating- Cooling- electricity

Passive:- Ventilation- Thermal mass

Passive usage of Solar Energy: Ventilation

• Solar chimney

• Down Draft cool

• tower

Passive usage of Solar Energy: heat mass

• Simply heat mass for storing energy

• Trombe wall

Active usage of solar energy: cooling

Active usage of solar energy:heating

• Solar collectors:– Themosyphon – Low Flow System– High Flow System

Active usage of solar energy:heating

Solar thermal collectors

Non concentrated:- Flat plate- Evacuated tubes

Concentrator type:- parabolic trough- parabolic dishes- heliostats- evacuated tubes

Non concentrated solar thermal collectors

Flat plate collectors: simple, hot water generation and auxilliary heating, heat losses in cold perois

Evacuated tube collectors:Lower heat losses in cold periods,For water heating and auxilliary heating

Concentrator type solar thermal collectors

• High temperatures possible

• Using coolants for heat

• transfer (mostly some oil)

Active usage of solar energy:electricity

• Always use concentrators (except photovoltaics)

• Concentrated solar energy is used to produce steam

• Normal steamturbine-generator power plants

• Stirling motors

Solar power towers

• Solar One in the USA

• PS 10 Spain:using molten sodium

Solar power plants

• SEGS: 354 MW(USA)

• Andasol 1: 20 MW

(Spain)

Other types of solar power plants

Process heat