Solar Energy IISolar Energy II

Solar Electricity Solar Electricity

Would you be willing to pay more for Would you be willing to pay more for electricity generated with solar power?electricity generated with solar power?

1 2

50%50%1.1. YesYes

2.2. NoNo

How much more would you be How much more would you be willing to pay?willing to pay?

1 2 3 4 5 6

17% 17% 17%17%17%17%1.1. NoneNone

2.2. 10% more10% more

3.3. 25% more25% more

4.4. 50% more50% more

5.5. 100% more100% more

6.6. I’ll pay whatever it I’ll pay whatever it costscosts

Technique 1Technique 1

Use mirrors to focus sunlight onto Use mirrors to focus sunlight onto water. water.

Boil the waterBoil the water Use a standard heat engine.Use a standard heat engine.

Parabolic MirrorParabolic Mirror

The shape of the The shape of the mirror causes all of mirror causes all of the light rays to the light rays to pass through a pass through a single point called single point called the focus.the focus.

Trough and circular parabolic Trough and circular parabolic mirrorsmirrors

Solar OvenSolar Oven

Trough SystemTrough SystemConcentrates solar Concentrates solar

energy up to 100 energy up to 100 times that of the sun.times that of the sun.

Temperatures limited to Temperatures limited to ~400~400C because heat C because heat exchange fluid (oil) exchange fluid (oil) breaks down. breaks down.

Efficiency of ~20%.Efficiency of ~20%.

Obviously varies Obviously varies throughout the day.throughout the day.

Improve PerformanceImprove Performance Use molten salt for heat exchange Use molten salt for heat exchange

fluid.fluid. Allows for temperatures up to Allows for temperatures up to

565565C. C. Disadvantage is that freezing point Disadvantage is that freezing point

of salt solution is 220of salt solution is 220C. Possible C. Possible problem of overnight freezing in problem of overnight freezing in pipes or waste energy keeping pipes or waste energy keeping pipes hot.pipes hot.

Trials underway in Sicily by Trials underway in Sicily by SiemansSiemans

Solar Electric Generating System Solar Electric Generating System (SEGS)(SEGS)

Currently generates ~350 MW of power Currently generates ~350 MW of power using 5 plants.using 5 plants.

HeliostatHeliostat

Uses movable Uses movable mirrors to focus mirrors to focus light on a tower.light on a tower.

Similar to parabolic Similar to parabolic mirror.mirror.

Solar One Facility Solar One Facility in Barstow, CA in Barstow, CA generates ~10MWgenerates ~10MW

Molten Salt Energy Storage

Solar ChimneySolar ChimneyAir in a very large greenhouse (2 to 30 km diameter) is heated by the sun and channeled to a tall chimney where there is a wind turbine.

Manzanares, Spain

PhotovoltaicsPhotovoltaics

Use Semiconductors Use Semiconductors to directly convert to directly convert sunlight into sunlight into electricity.electricity.

In principle, 77% of In principle, 77% of sunlight can be used sunlight can be used to produce solar to produce solar electricity.electricity.

HistoryHistory 1954: Bell Labs discovered that silicon wafers 1954: Bell Labs discovered that silicon wafers

are sensitive to sunlightare sensitive to sunlight Original cells required single crystal silicon. Original cells required single crystal silicon.

Very expensive to produce.Very expensive to produce. New developments allow for polycrystalline New developments allow for polycrystalline

cells. Much cheaper but less efficient.cells. Much cheaper but less efficient. Best cells are single crystal Gallium-Arsenide. Best cells are single crystal Gallium-Arsenide. Up to 42% efficient with light concentration Up to 42% efficient with light concentration

or 35.8% without (Sharp).or 35.8% without (Sharp).

Single Crystal and Polycrystalline Single Crystal and Polycrystalline CellsCells

Each cell produces ~0.5 volts. (Silicon Each cell produces ~0.5 volts. (Silicon single junction)single junction)

Amount of current depends on the Amount of current depends on the size/efficiency of the cell.size/efficiency of the cell.

To get higher voltages/power stack the To get higher voltages/power stack the cells up to make a solar panel.cells up to make a solar panel.

Industry average efficiency 14-18%Industry average efficiency 14-18% High efficiency cells (>20%)are still High efficiency cells (>20%)are still

expensive. expensive. Lower efficiency cells (~14%) are much Lower efficiency cells (~14%) are much

lower cost.lower cost.

Name Country DC Peak Power (MW)

Notes

Sarina Photovoltaic Power Plant

Canada 97 Constructed 2009-2010

Montalto di Castro Photovoltaic Power Station

Italy 84.2 Constructed 2009-2010

Finsterwalde Solar Park Germany 80.7 Phase I 2009Phase II,III 2010

Rovigo Photovoltaic Power Plant

Italy 70 Completed 2010

Olmedilla Photovoltaic Park

Spain 60 Completed 2008

Strasskirchen Solar Park Germany 54

Lieberose Photovoltaic Park

Germany 53 Completed 2009

Puertollano Photovoltaic Park

Spain 50 Opened 2008

New Cell Production

Solar Power, Springerville, AZSolar Power, Springerville, AZ

4.59 MW power station

A lot of smaller A lot of smaller installations used installations used in locations where in locations where to difficult, to difficult, expensive or expensive or environmentally environmentally damaging to take damaging to take power lines or power lines or generatorsgenerators

Solar ShinglesSolar Shingles

For a typical For a typical residential system, residential system, you would likely you would likely install 1-3 kW of PV install 1-3 kW of PV modules.  Today's modules.  Today's costs range from costs range from $8,000 to $10,000 $8,000 to $10,000 per kW of fully per kW of fully installed capacity.  installed capacity. 

19 kW solar roof19 kW solar roof

A lot of specialized UsesA lot of specialized Uses

Solar Power in SpaceSolar Power in Space

Deep Space Satellites Don’t Use Deep Space Satellites Don’t Use Solar PowerSolar Power

Solar CarsSolar Cars

2007 Cost Comparison2007 Cost Comparison

Major goal is to reduce costMajor goal is to reduce cost

Use amorphous silicon (thin films) Use amorphous silicon (thin films) Other materialsOther materials Concentrating collectorsConcentrating collectors Sun tracking systemsSun tracking systems Economy of scaleEconomy of scale