Good day, sunshine!
Please pass back the objective sheet.
 Please read the board!
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Why fossil fuels?
Why NOT Fossil Fuels?

What are the drawbacks of using fossil fuels?
“Alternative” energy sources are
sustainable sources!
Solar Power
Make Electricity
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Photovoltaics
Solar Thermal Towers
Make Heat
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Passive Solar
Active Solar
LET’S GO VISIT THE
SPACE POD!
Notes today:



Write down all the new TERMS you see today.
Don’t worry about definitions or explanations.
We will process these tomorrow! 
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
Between 2007 and Fall 2014,
the solar panels have generated
over 117,000 kWh resulting in
over $24,000 in energy savings.
That is the equivalent of planting
over 10,000 trees!
Ikea on I-10
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
3,388 panels
Completed June 2012

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Solar arc in
Japan
5,000 solar
panels
500,000kWh
of electricity
Our electric “grid” = power plants
connected to consumers
Photovoltaic Solar
Grid connected



Building connected to
power plant and
electric lines.
On cloudy days, at
night, building gets
electricity from the grid
Extra power can be
sold back to the electric
company!
Stand Alone

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Not connected to
power plant
Requires batteries for
night time
Can be far away from
cities!
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,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
Solar Leasing Program announced
2/10/15! (San Antonio)
Installation
companies own and
install solar panels
on homes; rent the
roof space from
homeowners
grid
Get electricity;
surplus sold to
CPS; rent check
from installation
companies
CPS receives
surplus kW to
distribute on
grid to other
customers
CPS avoiding another centralized
power plant!

“CPS Energy is our utility, it’s owned by us, the people of San
Antonio. And the idea of our utility putting solar on our
people’s rooftops, instead of building another centralized
power plant – it’s a very exciting thing, and Solar San Antonio
(SSA) is very supportive,” stated SSA Interim Executive Director
Anita Ledbetter in a news release. Ledbetter is also executive
director of Build Green San Antonio, the nonprofit sustainable
building resource and third-party green building certification
program.
Solar giants

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Germany! - requires
solar installation on
new buildings; gave
tax rebates for homes
installing photovoltaics.
China – increased
production of
photovoltaic panels
Price has dropped by
60%
Advancements

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
Photovoltaic road
panels!
Would keep road icefree.
Light up when pressure
is applied – safety at
night!
OTHER KINDS OF SOLAR
POWER
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Solar towers! 2007 near Seville
624 mirror, 35-story tower
Heat turns water to steam for turbines
Power for 6,000 homes
How it works

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
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!
Solar trough tech
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
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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
So what are the trade offs?

Benefits

Disadvantages