Joshua Pearce

E Sci 497C

The Pennsylvania State University

Rectifying Myths Related to Rectifying Myths Related to Solar EnergySolar Energy

Myth 1: All Solar Cells are the sameMyth 1: All Solar Cells are the same

GaAs and other III-V’sGaAs 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

CuInSeCuInSe22

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)

CdTeCdTe

Advantage:– High Efficiency in lab cells (~16%)-

prototypeDisadvantage:– Toxic material

Dye sensitized TiODye sensitized TiO22

It is “neat” (~10%) but….

–Potential instability

–Limits on maximum operation temperature

–Evaporation problems

–Cost

–Far from commercialization

Crystalline & Polycrystalline SiliconCrystalline & Polycrystalline Silicon

Advantages:– High Efficiency (~25%)– Established technology (The leader)– Stable

Disadvantages:– Expensive production– Low absorption coefficient– Large amount of highly purified feedstock

CrystallineSilicon

Amorphous Silicon

Amorphous SiliconAmorphous 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 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 Myth 2: Solar cells use more energy to produce than they energy to produce than they generate over their lifetime 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 PVBuilt in PV

Myth 3: There is not enough landMyth 3: There is not enough land

The total solar radiation falling on the earth is 1.2x1014kW, 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.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 sourceDistributed 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.

CarportsCarports

Myth 4: Switching to solar cells as Myth 4: Switching to solar cells as our primary energy source will our primary energy source will cause considerable unemploymentcause 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!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 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: Myth 5: Solar cells will not make Solar cells will not make economic sense until the distant future. economic sense until the distant future.

Today it makes economic senseToday 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 StationsCoast Guard Stations

1400 U.S. Coast Guard stations redesigned

Bus stops and emergency phonesBus stops and emergency phones

Street Lights and PhonesStreet Lights and Phones

Department of Environmental ProtectionDepartment of Environmental ProtectionCambria Office – $ Payback time 5 years for PVCambria Office – $ Payback time 5 years for PV

And costs continue to drop

Real World EconomicsReal 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?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 2004.

The U.S. ~2005-7

The FutureThe Future isis

SolarSolar

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