Transcript Activity 68 Follow-up 1. A 90° angle should have produced the most energy (faster motor) 3.

Activity 68 Follow-up
1. A 90° angle should have produced the
most energy (faster motor)
3. In most of the U.S. why don’t solar cells
produce enough electricity to run a house
through a full day or a full year? Use
evidence form this investigation to explain.
Solar photovoltaic cells: Advantages & Disadvantages
Advantages
• It’s pollution-free during use.
• It needs little maintenance, and operating costs are low.
• Sunlight energy in many places on Earth is plentiful.
• Solar works well in remote locations and places where
grid connection or fuel transportation is difficult.
• When grid-connected, solar electric generation can
displace the highest-cost electricity during times of peak
demand.
• Local grid-connected solar electricity can minimize
transmission losses.
• Solar is generating the most power among renewable
energies.
Disadvantages
• Buying and installing solar cells is costly, requiring a large initial
investment.
• There’s limited power density due to limited light intensity and
low efficiency of cells.
• To get enough energy for large applications, a large number of
photovoltaic cells are needed, increasing cost and land needed.
• Solar cells produce DC (direct current), which must be converted
to AC (alternating current) for use in existing distribution grids.
This incurs an energy loss of about 10%
• Like electricity transformed by nuclear or fossil-fuel power plants,
solar can’t be directly used to power a car. It is used in vehicle
applications by converting light energy into another form of stored
energy (i.e., battery-stored electricity or by electrolyzing water to
produce hydrogen).
Read page D-90
Activity 71
Title: Household Energy Efficiency
Problem: How can features in a home
affect the energy efficiency of a home?
Hypothesis: If _____________, then
____________________________.
• What is an energy-efficient home?
–One that uses less energy in
comparison to another
• How can you reduce your energy use?
• What things can’t be changes?
• Besides reducing energy use, how can
you save energy?
• On the back of your template, write activity
71 in the upper right hand corner
• Write “Data/Evidence:” on the top line
• Below that write
o Energy Use in the Home
o After the first passage is read, pause
and write down the main ideas you just
heard (don’t look in your book)
o Continue with the other headings
o Insulation and Windows
 Stop after each pencil and include all
headings in that section