Joshua Pearce E Sci 497C The Pennsylvania State University Rectifying Myths Related to Solar Energy

Myth 1: All Solar Cells are the same

GaAs and other III-V’s Advantages: –Awesome efficiencies (30%+) –Disadvantage: They simply cost too much. (only good for NASA) Material ---wafer----cost –c-Si 8” ~$100 –GaAs 4” ~$300 –InP 3” ~$800

CuInSe 2 Advantages: –High Efficiency in lab cells (~17%) Disadvantages: –Instability in hot/wet environments –High temperature deposition –Un-established deposition technology –The availability of Indium (silver)

CdTe Advantage: –High Efficiency in lab cells (~16%)- prototype Disadvantage: –Toxic material

Dye sensitized TiO 2 It is “neat” (~10%) but…. –Potential instability –Limits on maximum operation temperature –Evaporation problems –Cost –Far from commercialization

Crystalline & Polycrystalline Silicon Advantages: –High Efficiency (~25%) –Established technology (The leader) –Stable Disadvantages: –Expensive production –Low absorption coefficient –Large amount of highly purified feedstock

Crystalline Silicon Amorphous Silicon

Advantages: –Cheaper than the glass, metal, or plastic you deposit it on –Established technology –Low-cost substrates –Excellent ecological balance sheet Disadvantages: –Only moderate stabilized efficiency (~13%) –Instability- It degrades when light hits it :(

Abundance of all raw materials The amorphous silicon cells manufactured from one ton of sand could produce as much electricity as burning 500,000 tons of coal.

Myth 2: Solar cells use more energy to produce than they generate over their lifetime

For cells in production now the energy payback is between 6 months and 3 years! (full system 2-5 years) Solar cells produce enough energy to reproduce themselves ~40 times!! For Built-In PV systems in which solar cells replace a buildings structure the energy payback can be measured in days!

Built in PV

Myth 3: There is not enough land

The total solar radiation falling on the earth is 1.2x10 14 kW, which is roughly 10,000 times current world consumption. The fossil fuel production of the entire world could be replaced by hydrogen generated by photovoltaic arrays on 53 million hectares of arid land (less than 2% of the area of the world’s deserts).

Even brighter in the U.S. Solar Cells covering 0.3% of the land in the U.S. (1/4 of the area currently occupied by railroads), could provide all of the U.S.'s electricity needs.

Distributed energy source Located near the consumer in order to eliminate transmission losses (which can be higher than 50% on modern grids). Panels could be placed on roofs, built into roofs, building facades, carports, highway sound barriers, etc. Any surface which is exposed to sunlight is fair game.

Carports

Myth 4: Switching to solar cells as our primary energy source will cause considerable unemployment

A 1997 Pembina Institute report found that for every million dollars invested: –36.3 jobs are created in the energy efficiency sector –12.2 in the renewable energy sector In conventional energy, an average of only 7.3 jobs are created.

PV: net job producer! Jobs created with every million dollars spent on: –oil and gas exploration: 1.5 –on coal mining: 4.4 –on producing solar water heaters: 14 –on photovoltaic panels: 17

Coal only employs 80,000 –It is predicted that by 2010, approximately 70,000 new jobs could be created as a result of the increased demand for photovoltaic, solar hot water, and related solar energy systems through the installation of only one million solar energy systems. (3%)

Myth 5: Solar cells will not make economic sense until the distant future.

Today it makes economic sense Now it makes sense for remote sites that are too far from power, or where the power is too unreliable. –Costs for power lines range from $8000 to $75,000 per mile. –As a general rule, if you are more than 1/2 mile from a line, solar is probably the best alternative.

In areas that have grid power, where the cost of tearing up the streets and/or other construction are expensive. Where solar can’t be beat now

Coast Guard Stations 1400 U.S. Coast Guard stations redesigned

Bus stops and emergency phones

Street Lights and Phones

Department of Environmental Protection Cambria Office – $ Payback time 5 years for PV

And costs continue to drop

Real World Economics Price reduction of 7.5%/yr during which the average worldwide production of modules increased by 18%/yr. Economy of scale -- direct competition with fossil fuel as an energy source it is generally agreed that 100MWp PV plants must be constructed

When will this happen? For example, N. Mori, the executive managing director of the Photovoltaic Power Generation Technology Research Association, predicts that Japan will begin producing 100MWp/yr factories between 2003 and The U.S. ~2005-7

The Future is is Solar Solar 200,000+ homes in the U.S. use some type of photovoltaic solar technology- and the market expanded over 52% last year