4 types of Solar power Photovoltaics Concentrated tower

4 types of Solar power Photovoltaics Concentrated tower systems Passive and active heating systems

Photovoltaics

How does it work? Photovoltaic cells contain a semiconductor material – creates a flow of electrons (electricity!) when hit by light. Batteries store electricity for cloudy days or nights.

Discovery Green down town Two arrays totaling 256 solar panels how much is it generating RIGHT NOW? ?

Ikea on I-10 3, 388 panels Completed June 2012

Our electric “grid” = power plants connected to consumers

Grid-connected systems Home still connected to grid for regular electricity at night or on cloudy days. Doesn’t require batteries since the grid is the back up. Buildings making more electricity than they use can sell electricity back to the grid! (You’d get an electric check instead of a bill!)

Solar panels are great for remote locations – “stand alone” Customers don’t need to be connected to the grid Must have batteries for back up.

Solar update! US solar industry – record growth in 2012, 16, ooo panels installed in nation, record 76% growth Texas is in the top 10 states for solar installation and has the “most untapped potential” for solar (still just. 1%of electricity) Module costs have dropped 60% last two years

Other kinds of solar power

Concentrated solar towers! 2007 near Seville 624 mirror, 35 -story tower Heat turns water to steam for turbines Power for 6, 000 homes

Ivanpah Solar Electric Generating System – Mojave desert California 5. 5 square miles Power for 140, 000 homes Molten salt stores heat to be released on demand – even at night.

How it works Light bounces off mirrors and is concentrated at top of tower. Molten salt is pumped to top of tower where light heats it up Molten salt is used to turn water to steam turbine generator electricity! Connected to existing electric grid.

Mirrors track sun’s movement

Passive solar – heats air or water; no electricity

• • • In winter when sun is low in sky, light enters, bounces, turns into heat which is trapped by the super-insulated windows and walls. In summer, wide roof overhang blocks sunlight, keeping house cool. Windows face south and west.

Hudson Passive Project NY

Villa Nyberg, Sweden

Passivhaus, Germany

Fablab house, Madrid Spain

Crossways, UK

Vogel House, Switzerland

Active systems

Active systems • • • Water pipes on roof heat up. Water brought down into heat exchanger in house which warms the shower water. Cooled water pumped back to roof to warm up. • Can also be used to heat a house with radiators.

Active systems

Water piping on roof warms water. (New Hampshire)

Active systems Water pipes on roof heat up. Water brought down into heat exchanger in house which warms the shower water. Cooled water pumped back to roof to warm up. Can also be used to heat a house with radiators.

Active system

Solar giants Germany! - requires solar installation on new buildings; gave tax rebates for homes installing photovoltaics.