Solar Energy

Solar Energy

Types of solar energy

• Solar Thermal

  • Radiant energy to heat

  • Very similar to a coal electricity plant

• Solar Photovoltaic

  • Radiant energy directly to electricity using semiconductor technology

  • Solar can be scaled from large to small amounts of generation

The journey of a photon

• Created in the core of the sun by nuclear fusion reaction

• Millions of years to bounce out to surface of sun

• Zips to earth in about 8 minutes

• Passes through the atmosphere

• Strikes a solar panel and dislodges an electron in the PV panel

• Electron is collected and delivered to the grid

Solar radiation

• Conversion of mass energy to radiation

• Converts hydrogen to helium

Solar radiation

• [Solar

  Reaction](http://m.teachastronomy.com/astropedia/article/Nuclear-Reactions-in-Main-Sequence-Stars)

  

Solar energy

• Peak solar power about 1000 watts per square meter

• Solar power is usually measured for this level of sunlight

• However, sun is not always this bright

• Our sunniest locations get about 5.5 kWh per square meter per day of sun energy

Electromagnetic Spectrum

Blackbody Spectrum

Solar Photovoltaic

• Converts sunlight directly to electricity

• Commercially available panels have 15% -- 20% efficiency of solar

  energy in to electrical energy out

Photovoltaic electricity plants

Agua Caliente

• Highest power photovoltaic power facility in 2013

• Yuma, Arizona

• 397 MW peak production

• 25 year power purchase agreement

Agua Caliente Data

Agua Caliente Monthly Production Data

Solar thermal plants

Parabola

A parabola is the shape that reflects parallel lines to a point. Since the sun's rays are essentially parallel, this focuses the sun to a point.

Concentrating solar power trough

We heat oil along large parabolic mirrors.

SEGS

• Solar Energy Generating Systems

• First solar thermal plants

• Daggett, CA

• Built in 1984 and 1985

Ivanpah

• 377 MW

• Concentrating solar thermal power towers

• Near Las Vegas, Nevada

• No thermal storage

• Natural gas backup

Ivanpah solar plant

Solar power tower

Solar Thermal

Advantages

• Uses well established thermal electricity technology

Disadvantages

• Needs water, scarce in sunny climates

Developing world solar

• Phone charging

• Water pumping

• Lighting

Solar Lantern

d.light

Solar Installed Capacity

IEA PVP2012

What scale is needed?

• World primary energy consumption approximately 500 EJ

• Power = Energy / Time

• Joules / seconds = Watts

  $P = 500 EJ / 3.15 \cdot 10^{7}\ seconds = 16 TW$

Photovoltaic learning curve

Solar Energy

• Approximately 1000 watts per square meter on the surface of the earth

  at peak

• 170 watts per square meter average insolation