Transcript Project Overview - Pennsylvania State University

Rectifying Myths Related to
Solar Energy
Joshua Pearce
E Sci 497C
The Pennsylvania State University
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
– GaAs
– InP
8”
4”
3”
~$100
~$300
~$800
CuInSe2

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 TiO2

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
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 1.2x1014kW, 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.

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.
Where solar can’t be beat now

In areas that have grid
power, where the cost
of tearing up the
streets and/or other
construction are
expensive.
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 2004.
 The U.S. ~2005-7

200,000+
homes in the
U.S. use some
type of
photovoltaic
solar
technologyand the market
expanded over
52% last year
The Future
is
Solar