Transcript Energy Conservation

Solar Energy
Physics 1303
3/26/03
Three forms of solar energy.
Passive Solar
Active Solar
Photovoltaic
Passive Solar Energy
Sensible architectural design
Use sun in the winter
Avoid in the summer.
Cold climates- large glazing which
may be insulated at night and
opened during the day.
Hot climates - blocking the sun and
providing good ventilation.
Passive Design
Arizona Cliff
Dwelling is an
example of
traditional lowtech solution to
space heating and
cooling needs.
Passive Design
This is a modern New
Mexico version.
There is movable
isolation to put in
place at night.
Passive Design
Another interesting
design.
The wall is down and
the passive
collector is
collecting solar
energy
Passive Design
In this mode, the
wall is up and the
building is storing
solar energy or
blocking summer
heat gain.
An innovative passive design
Roof Pond House in
Atascadero,
California
Active Solar Energy
Use pumps and solar collectors to
provide energy.
Two types of solar collectors:
– flat plate
– concentrating
Flat Plate Collector
Made of a black absorbing plate with
water running through it or air
blowing past it.
Usually a flat plate collector has a
glazing to stop heat from escaping.
Efficiency 50% or better.
Flat Plate Collector – Hot Water
Heater
Low cost heater in
the roof of this
modest Miami
house
Flat Plate Collector – Hot Water
Heater
Low cost heater in
the roof of this
modest San
Antonio house
Flat Plate Collector – Hot Water
Heater
Low cost heater in
the roof of this
modest Miami
house
Flat Plate Collector – Hot
Water Heater
 Solar water heater
system has four
components:
 Collector
 Tank
 Pump
 Controller
Flat Plate Collector
Flat plate collectors
being tested.
Flat Plate Collector
Flat Plate Collector
components:
 Plate with tubing
 Insulation
 Glazing
Concentrating Collector
A concentrating collector includes
some kind of lens or mirror.
Tracks the sun.
 High temperature.
 Efficiency near 50%.
Concentrating Collector
Components:
 Optics
 Glazing
 Absorber
 Insulation
 Tracking
Concentrating Collector
This one uses a
mirror and has no
glazing
Concentrating Collector
Used to be on the
roof of the Bell
center.
Concentrating Collector
This is the solar
concentrating
collector on the
CPS Headquarters
building on San
Pedro.
It runs the airconditioning
system
Flat Plat Collector Problem
Stop and work the
problem.
Photovoltaics
Photovoltaic systems convert solar
energy directly into electricity. They
have efficiencies near 10%.
Photovoltaics
PV-powered airplane.
Is this really a good
idea?
Photovoltaics
PV arrays are widely
used for low power
loads.
Photovoltacis
A PV array is made
up of several
panels and a panel
is made up of
several cells.
Photovoltaics
A complete system
has an array, a
battery, an
inverter and a load.
The system can
supply either DC or
AC loads.
Photovoltaics
The inverter
converts the DC
voltage from the
PV array into an
AC signal to power
AC loads or to
connect to the
grid.
Photovoltaics
 Laurel Kaesler and
Frank Ehman
designed and built
the PV Project in
the Physics
Department
Photovoltaics
 The PV project has
4 components:
 Array
 Controller
 Battery
 Load
Photovoltaic
Controller
Photovoltaics
 The load is a pair
of fluorescent
lights in my Physics
office.
 These lamps supply
the only light that
I use in this
office.
Photovoltaic
This is the solar
array on the CPS
Headquarters
building on San
Pedro.
Photovoltaic
 The output of the
array is inverted
into an AC voltage
and fed back to
the grid.
Photovoltaics
A high-tech solution
is to use PV to
capture sunlight as
electricity and use
the electricity to
produce
microwaves that
are beamed back
to earth.
PV Problem
Stop and work the
problem.
Solar Energy
Do you think solar
energy will able to
replace a
significant
fraction of the
energy needs of
our society?