This document provides an overview of solar power, including its history, technologies, and future potential. It discusses both active solar systems that use mechanical means to distribute solar energy, as well as passive solar techniques used in building design. Photovoltaic cells that directly convert sunlight to electricity are described as the basic building block of solar energy production. Larger scale technologies like trough systems and concentrating solar power that use mirrors to focus sunlight are also summarized. The document outlines key aspects of passive solar home design and concludes by discussing the Department of Energy's projections that solar costs will be competitive with fossil fuels by 2020.

1. Solar Power
An introduction to the history,
technologies, policy applications
and future of solar power.

2. Solar Power: A brief history
• 7th century B.C. – A
magnifying glass is used to
concentrate the sun’s rays
to light fires for light, warmth
and cooking.
• 1st - 4th century – Roman
bath houses are built with
large, south-facing windows
to aid in temperature control
• 13th century – Ancestors of
the Pueblo people known
as the Anasazi build south-
facing cliff dwellings that
capture the warmth of the
winter sun.
Above: Anasazi cliff dwellings demonstrate
passive solar design techniques. Passive
design is also noted in the architecture of early
Mesopotania and the highly developed
societies of early South America.
[from www.eere.energy.gov]

3. Solar Power: A brief history
• 1839 – French scientist Edmond Becquerel discovers the
photovoltaic effect while experimenting with an electrolytic cell
composed of two metal electrodes in conducting solution.
• 1954 – Chapin, Fuller and Pearson at Bell Telephone
Laboratories develop the first silicon photovoltaic (or PV). It’s
the first solar cell capable of generating enough power from
the sun to run everyday electrical equipment.
• Mid-1950s to 1960 – PV efficiency increases from 6%
efficiency to 14% in 1960 (Hoffman Electronics). Silicon solar
cells become the most widely accepted energy source for
space applications.
• 1970 – Dr. Elliot Berman in conjunction with Exxon
Corporation designs a significantly less costly solar cell,
bringing the price down from $100 per watt to $20 per watt.

4. Solar Power: A brief history
• 1970s – Energy Crisis: Oil costs $40/barrel, Solar R&D
budget increases to $150 million and a 40% tax credit is
offered for residential solar system installs up to $10,000.
• 1978 – NASA’s Lewis Research Center installs a 3.5-kilowatt
photovoltaic system on Papago Indian Reservation in AZ.
The world’s first village PV system provides enough electricity
for 15 homes and eventually for the entire village (in 1983).
• 1982 – The first megawatt-scale PV power station goes on
line in Hisperia, CA.
• 1985 – Researchers at University of South Wales break the
20% efficiency barrier for silicon solar cells.
• Mid-1980s – Oil costs $10/barrel, solar R&D funding is
slashed 75% and residential tax credits are eliminated. 90%
of solar thermal manufacturers go out of business.

5. Solar Power: A brief history
• 1993 – Pacific Gas and
Electric Company installs
the first grid-supported PV
system in Kerman, CA.
This 500-kilowatt system is
the first “distributed power”
PV installation.
• 1996 – The U.S.
Department of Energy and
an industry consortium
begin operating Solar Two –
an upgrade to the Solar
One concentrating solar
power tower.

6. Solar Power: A brief history
• 1998 – Subhendu Guha invents
the flexible solar shingle.
• 1999 – Spectrolab, Inc. and the
National Renewable Energy
Laboratory develop a 32.3%
efficient solar cell.
• 2001 – Home Depot begins
selling residential solar power
systems in three San Diego
store, expanding sales to 61
stores nationwide a year later.
• 2002 – PowerLight Corporation
installs the largest rooftop solar
power system in the U.S. – a
1.18 megawatt system at the
Santa Rita Jail in CA.
Above: Santa Rita Jail in Dublin, CA.
This 1.18 megawatt PV system spans
three (3) acres and supplies 30% of the
jail electricity.
[Credit: PowerLight Corporation]

7. • Declining costs coupled with improved reliability, efficiency
and availability have led to an increase in active solar
technology use and application worldwide. PV technologies
have shown large utility-connected application increases for
homes and businesses. Japan, Germany and the United
States have led this boom, with California leading the way for
the US.
• A flourishing solar industry (particularly grid-connected)
requires three main ingredients: government support,
competitive pricing (which may require high electric prices and
abundant sunshine.
• Passive technologies are frequently integrated in new building
construction.
• Environmentally conscious consumers have long seen the
potential benefits PV systems offer: a quiet, clean energy
alternative with no moving parts.

10. Solar Power: Solar today
• Domestic sales of PVs doubled in 1999, and PV costs have
plummeted form $1.00/kWh in 1980 to $0.20/kWh in 2000.
• The U.S. Department of Energy estimates that costs will be
cut in half again in the next few years.
• Solar water heating, which is cost competitive in much of the
U.S., is used in 2.1 million buildings in the U.S.; Tokyo alone
has one that 1 million buildings using the technology.
• In 2003, 1600 Pennsylvania Avenue installed a 9-kilowatt PV
system which feeds directly into the White House distribution
system. Two solar thermal systems were also installed: one
to heat the pool and spa and one to provide domestic hot
water.
• Common PV applications included telecommuncations
equipment, consumer products, emergency power, space
applications, building integration systems, water pumps, solar
lighting, gate openings and roofing materials.

11. Solar Power: Financing & Incentives
• The cost of a solar system is directly proportional to how
much energy is required. Most vendors offer package
systems that range from 1 kW for a small energy-efficient
home to 2.5 kW for an average large home.
• To determine the desired size for a grid-connected solar
electric system the following questions should be considered:
– What is your monthly electrical usage?
– How much can you reduce your electrical use?
– What percentage of electrical needs do you want to meet with
your system?
– What is the amount of sunlight available at your site?
– What is the rated output of the solar electric panels you are
considering purchasing?
– How many panels are needed? What is your expected peak
load? What size inverter do you need? What size battery bank
do you require?

12. Solar Power: Financing & Incentives
• A typical household PV system costs between $10,000
and $40,000, before incentives and rebates. The
average home could meet 80% of its electricity needs
with a 2 kW system.
• The primary factors influencing PV economics
– Amount of direct sunshine your location receives.
• The amount of solar energy falling per square meter in Arizona in
June is typically three times greater than that falling in Maine.
• The quantity is also affected by the time of day, the climate and
regional air pollution.
– Cost of electric grid power.
– Long-term interest rates.
– Available government incentives, subsidies and rebates.
• Corporate Deduction: Franchise Tax Deduction
• Property Tax Exemption
• Utility Loan Programs: Austin Energy Solar Loan Program
• Utility Green Pricing Programs: Austin Green Choice
• Outreach Programs: Texas Million Solar Roofs Partnership

13. Solar Power: 2003/2004 Energy Bill
• Proposed Residential Solar Tax Credits:
– Residential PV and solar water heating installations
receive a tax credit equal to 15% of the total cost of
equipment, capped at $2,000 each.
• Proposed Renewable Energy Research and
Development Appropriation Levels:
– $595,000,000 for FY 2004
– $683,000,000 for FY 2005
– $733,000,000 for FY 2006

14. Solar Power: The Future
• The U.S. Department of Energy Solar Energy
Technologies Program predicts that major breakthroughs
will occur in PV research and development which
include:
– New materials
– New cell designs
– Novel approaches to product development
– Solar transportation
– Solar clothing
• A desert area 10 miles by 15 miles could provide 20,000
megawatts of power.
• If solar cells were placed on the rooftops of the ten (10)
largest U.S. retail chains (Walmart, Target, etc.), the
electricity needs of the United States could theoretically
be met.

15. Solar Power: The Future
• The U.S. Department of Energy estimates that
by 2020, solar energy costs will be competitive
with fossil fuels. It is projected that by 2020,
retail electricity (intermediate load) will be $0.04
- $0.06/kWh.
• To achieve this “goal”, a total commitment is
required:
– Robust and timely federal R&D solar energy program
– Innovative minds in the field
– State and federal government incentives
– Education and resource availability

16. Solar Power: How Solar Works
• Solar cells are converters.
They take energy from the
sunlight and convert that
energy into electricity.
• Most solar cells are made
from silicon, which is a “semi-
conductor” or a “semi-metal”
• Solar cells are made by
joining two types of semi-
conducting material: P-type
and N-type.
• At the atomic level, light
consists of pure energy
particles, called “photons”.
Above: The world’s largest solar power
facility near Kramer Junction, CA. The
facility covers more than 1000 acres
with a capacity of 150 megawatts.
[www.eere.energy.gov]

17. http://www.eere.energy.gov/solar/multimedia.html

18. Solar Power: How Solar Works
Above: The photons from the sun penetrate and randomly strike the
silicon atoms. The atom becomes ionized, passing energy to
the outer electron, thereby allowing the outer electron to break
free from the atom. An electric current is created.
[www.powerlight.com]

19. 8/6/2022 Tyler Hanson 19
Solar Power
• Active Solar systems and technology
• Active solar systems use solar collectors and additional electricity to power pumps or
fans to distribute the sun's energy. The heart of a solar collector is a black absorber
which converts the sun's energy into heat. The heat is then transferred to another
location for immediate heating or for storage for use later. The heat is transferred by
circulating water, antifreeze or sometimes air
• Passive solar Technology
• A passive system does not use a mechanical device to distribute solar heat from a
collector. An example of a passive system for space heating is a sunspace or solar
greenhouse on the south side of the house. Although passive systems are simpler, they
may be impractical for a variety of reasons
• Eere.energy.gov

20. What is Active Solar
• Harnessing incoming solar
radiation through the use of solar
collectors to produce energy
• Uses include water heating for use
in the home and in swimming
pools. As well as space heating in
the home
Active solar System
Newenery.org

21. 8/6/2022 Tyler Hanson 21
Solar energy production
systems
• Photovoltaic Cells : the building block of
solar energy
• Trough Solar Systems-large scale energy
production
• C.S.P. – Concentrating Solar Power

22. Photovoltaic Cells
• Solar cells convert sunlight directly into electricity. They
are made of semiconducting materials similar to those
used in computer chips. When sunlight is absorbed by
these materials, the solar energy knocks electrons loose
from their atoms, allowing the electrons to flow through
the material to produce electricity. This process of
converting light (photons) to electricity (voltage) is called
the photovoltaic (PV) effect.

23. 8/6/2022 Tyler Hanson 23
Photovoltaic Cells
• Commercial photovoltaic cells
deliver, as electricity,
approximately 15% of the solar
energy that hits them. Technical
improvements are steadily
increasing the efficiency and
reducing the cost.
(solarenergysociety.ca)
• However high performance
cells in development now are
producing energy from nearly
one third of the suns incoming
energy!!

24. 8/6/2022 Tyler Hanson 24
Trough systems
• Parabolic-trough systems concentrate
the sun's energy through long
rectangular, curved (U-shaped) mirrors.
The mirrors are tilted toward the sun,
focusing sunlight on a pipe that runs
down the center of the trough. This
heats the oil flowing through the pipe.
The hot oil then is used to boil water in a
conventional steam generator to
produce electricity.
• A collector field comprises many troughs
in parallel rows aligned on a north-south
axis. This configuration enables the
single-axis troughs to track the sun from
east to west during the day to ensure that
the sun is continuously focused on the
receiver pipes. Individual trough systems
currently can generate about 80
megawatts of electricity, enough to power
a city of 110,000 people. Of course,
individual systems can be grouped to
provide more power.
• Often these systems are “hybridized”
with fossil fuels to produce power 24
hours a day.
• The first parabolic trough solar power
plant became operational in 1984, and
continues to provide power today.

25. 8/6/2022 Tyler Hanson 25
CSP
• A dish/engine system uses a
mirrored dish (similar to a very
large satellite dish). The dish-
shaped surface collects and
concentrates the sun's heat onto a
receiver, which absorbs the heat
and transfers it to fluid within the
engine. The heat causes the fluid
to expand against a piston or
turbine to produce mechanical
power. The mechanical power is
then used to run a generator or
alternator to produce electricity
• (NREL.com)

26. 8/6/2022 Tyler Hanson 26
Passive Solar
• A passive system does not use a mechanical device to distribute
solar heat from a collector. An example of a passive system for
space heating is a sunspace or solar greenhouse on the south side
of the house. Although passive systems are simpler, they may be
impractical for a variety of reasons
• Solar home design- layout
1.Direct Gain- sunlight directly enters the space it is
intended to heat, and is stored and released in that
area.
2.Indirect gain- Trombie Walls
3.Isolated Gain- sun rooms
• Heating
• Lighting

27. Solar Home Design
• Aperture (Collector): the large glass (window) area through which sunlight enters
the building. Typically, the aperture(s) should face within 30 degrees of true south and
should not be shaded by other buildings or trees from 9 a.m. to 3 p.m. each day
during the heating season.
• Absorber: the hard, darkened surface of the storage element. This surface—which
could be that of a masonry wall, floor, or partition (phase change material), or that of
a water container—sits in the direct path of sunlight. Sunlight hits the surface and is
absorbed as heat.
• Thermal mass: the materials that retain or store the heat produced by sunlight. The
difference between the absorber and thermal mass, although they often form the
same wall or floor, is that the absorber is an exposed surface whereas storage is the
material below or behind that surface.
• Distribution: the method by which solar heat circulates from the collection and
storage points to different areas of the house. A strictly passive design will use the
three natural heat transfer modes—conduction, convection, and radiation—
exclusively. In some applications, however, fans, ducts, and blowers may help with
the distribution of heat through the house.
• Control: roof overhangs can be used to shade the aperture area during summer
months. Other elements that control under- and/or overheating include: electronic
sensing devices, such as a differential thermostat that signals a fan to turn on;
operable vents and dampers that allow or restrict heat flow; low-emissivity blinds; and
awnings.

28. Solar Home Design
• In the northern hemisphere the south side of a home or building
always receives the most solar radiation, or light.
• Therefore orienting a home with its broad side towards the south,
and placing more windows on that side and the least amount on the
west optimizes the effects of the sun in the winter.
• Homes designed with extended overhangs or “eves” around the
homes roof line aid in shading of the high summer suns rays.
• Using a 6 inch exterior wall width also aids in the insulation of the
home. As well as using quality double pained windows, with wood or
vinyl casements to lower heat exchange through the materials.
• Also a heat absorbent flooring material used beneath south facing
windows helps in radiant heating of the home.

29. Solar Home Design
• A window's heat transmittance is measured by U-factor. A smaller U-
factor provides more insulating value than a larger one. The smaller
the number, the better. With today's technology, a window is
considered energy efficient if its U-factor is less than 0.40. To
achieve this energy-efficiency standard, the glass is coated with a
very thin layer of material that is engineered to transmit or reject
certain frequencies of radiation. This coated glass is called low-
emissivity (low-e) glass.
• Glass's transmittance is measured by solar heat gain coefficient
(SHGC), which is a decimal number less than one. A number of 0.60
means that 60 percent of the solar radiation passes into the house
and 40 percent is rejected back into the environment. Passive solar
heating requires a high SHGC—in other words, a window that lets
solar radiation pass into the space.

30. Solar Home Design
• Quite often passive solar homes are built using glass that rejects
solar energy (low SHGC). This can be a costly mistake. When
selecting the glass, here are some general rules of thumb you can
follow:
• East- and west-facing glass should have a low SHGC (less than
0.40).
• South-facing glass should have a high SHGC if the house has a
proper overhang. If it doesn't, you'll need a low SHGC glass, but then
you won't have a solar house because you're rejecting the solar gain.
• The SHGC makes little difference on the north facade. Because
most windows get low U-values by adding low-e coatings, it comes
at a price.
• Typically, the low U-value windows also reject most solar gains (low
SHGC). Therefore, it may be difficult to buy a low U-value window
with a high SHGC. The right choice is dependent upon the climate.

31. Passive heating
• Trombie Wall- basically a thermal mass on the interior of a home
heated by sunlight from south facing windows that then radiates
heat throughout the interior of the home. Solid masonry wall works well –
storing about 200 calories per kg per degree centigrade. The more massive
the better. Also needs to be thermally conductive so that the energy stored
in one place moves uniformly across the wall for re-radiation. Also dark
colored.
• Solarium- greenhouses or sunrooms attached to the home can
provide substantial heat resources for a home.

32. Solar Energy in Texas
Texas has more renewable energy
potential than any other state due
to its size and diverse climate.
The main obstacle is developing
technology that can tap non-
polluting resource.

33. TEXAS FACTS
• TX is largest user of energy in the US
• TX is the sixth largest user of energy in the
world
• TX imported 7 billion dollars of energy last
year, and this amount increases by 1
billion dollars each year
• In less than 40 minutes, Texas receives
more solar energy than all fossil fuels used
in America could produce in one year.

34. Solar Resources in Texas
• Texas Solar Energy Society for Texas
• Texas Renewable Energy Industries
Assoc.
• Texas Renewable Energy Education
Campaign
• Texas Million Solar Roofs Partnership

35. Texas Solar Energy Society
• Non-profit organization educating citizens, gov’t and
institutions on readiness and benefits of renewable
energy technologies and their practical applications.
• Research projects include passive solar buildings,
natural lighting for buildings, solar electric cars, wind
powered electricity, hydropower, solar thermal
applications, renewable and general energy education
• The TXSES chapter in the Dallas-Fort Worth area is
called the North Texas Renewable Energy Group, or
"NTREG
• For more info go to www.txses.org

36. Texas Renewable Energy
Industries Association
• A non-profits consisting of over 100member companies
and organizations providing products, services and
information in the areas of solar electricity and hot water,
small and large wind generation, and more!
• A referral service for individuals, companies and
agencies seeking access to renewable energy expertise
and technology.
• Maintain an effective relationship with our local, state,
and national governments.
• Increase public awareness of the "here and now"
contribution of renewables, as well as of their vast
potential.

37. Texas Renewable Energy
Education Campaign
(TEED)
• NEED programs in Texas provide energy education
curriculum materials and training to K-12 students and
teachers.
• TX NEED Project
Contact: Mary Spruill
NEED Project
PO Box 10101
Manassas, VA 20108
TEL: (703) 257-1117
FAX: (703) 257-0037
EMAIL: info@need.org
WEB: www.need.org

38. Texas Million Solar Roofs
Partnership
• Texas Million Solar Roofs Partnership (TMSRP) was
formed in August, 1999 with seventeen charter
members. Each of these member organizations signed a
TMSRTP agreement form, committing to a specific
number of solar installations by 2010. In September
1999, Texas became the MSRI's 41st partner.
• TMRSP will help solar instillations by
• piloting a certification and accreditation program for PV practitioners
training and certification program
• developing and implementing a plan for the MSR registry
• communicating the program's progress and results through a variety of
methods, like e-newsletters, this web site, and press releases

39. Where is MSRI now?
• To date, 178.3 kW of PV and 13,500 sf of
Solar Hot Water Heating systems plus 8
residential units have been installed.
• ?Are one of the 8 residential units include
Bush’s Crawford ranch?
• Published 3/17/04

40. County Examples
• El Paso Solar Energy Association
• Solar San Antonio, Inc.
• North Texas Renewable Energy Group
http://www.txses.org/ntreg.php

41. El Paso Solar Energy Association
• The El Paso Solar Energy Association (EPSEA), a non-
profit, was founded in 1978 and is the oldest,
continuously active, local solar organization in the United
States.
• Purpose is to help facilitate the further development and
implementation of solar energy and other renewable
energies with an economic, social, ecologic, and
education perspective predominantly in the Western
Texas, southern New Mexico, and Northern Mexico
• Conducts demonstrations, info booths, and project
development work in the above regions about renewable
energy.

42. Solar San Antonio
• Non-profit working to educate and advocate a viable
future for future people in San Antonio and South Texas
using renewable energy and sustainable practices.
• Working with multiple services to create a showcase of
solar energy.
• Assisting to provide an exemplary solar powered
commercial building.
• Partner with SA Development Agency to provide energy
efficiency, solar hot water, and electricity to a low income
family.
• Establish a resource center
• Assist SAISD to implement a solar installation.

43. NTREG
• The TXSES chapter in the Dallas-Fort Worth area is
called the North Texas Renewable Energy Group, or
"NTREG". They maintain a discussion group at
http://groups.yahoo.com, named "ntreg", and schedule
regular meetings. For more information, please join the
discussion group or contact Mike Correale.

44. Federal Resources:
Solar Energy Technologies
Program
• One of 11 programs within the U.S. Department of
Energy's Office of Energy Efficiency and Renewable
Energy.
• Focus on developing solar energy technologies to
power our world.
• The Office of Energy Efficiency and Renewable Energy
under DOE
• Great resource for general source of information, links to
incentives by state, and for potential research partners in
industry or university.
• Lots of grant information for projects!!!!
• http://www.eere.energy.gov/solar/

45. Federal Programs
Million Solar Roofs- Clinton set up June 1997
• an initiative to install solar energy systems on one million
U.S. buildings by 2010, specifically solar electric systems &
solar thermal systems
• By soliciting volunteer participation with state, local, and
groups the DOE hopes to remove barriers to solar energy
use and to develop and strengthen demand for solar
energy products and applications by developing a pool of
existing federal lending and financial options and
leveraging other financial support.
• The MSRI participates in state incentives and other
resources. National Database of State Incentives for
Renewable Energy & partnerships can apply annually with
DOE grants. In 2001, 34 partners received $1.5 mil for
development & implementation activities.

47. Federal Programs cnt’d
Rebuild America (U.S. Dept of Energy)
• Part of the Office of Energy Efficiency and Renewable
Energy. Rebuild America is a network of hundreds of
community based projects across the nation who are
saving energy by enhancing the quality of life through
energy efficiency and renewable energy technologies.
Created by the U.S. Department of Energy (DOE) in 1994,
Rebuild America serves as a mechanism for revitalization
and job creation in many U.S. communities.
• Energy Education- provides materials, resources and
background information to teachers and parents who are
interested in facilitating learning through the investigation
of energy efficient topics.
• Energy Sources : This includes having students learn the
changing sources for energy over time, various uses for energy,
and the sources of energy. It also introduces the concept of
renewable and non-renewable categories for energy sources.

48. Energy Plan
• Tax credits of up to $2,000 for installing solar panels on
residential homes.
• While solar energy technologies have undergone
technological and cost improvements and are well
established in high value market areas continued
research is needed to reduce costs and improve
efficiency. Solar accounts for 1% of renewable electricity
generation and 0.02% of total U.S. electrical supply.
• Ironic eh since both the Crawford Ranch and the White
House are powered by solar energy!
• Also,

49. Suggestions for state & local
incentives
• At the present time there are no financial assistance
programs for individual homeowners purchasing solar
energy systems. However, consumers can take
advantage of net energy billing, property tax and
franchise tax exemptions Property Tax Exemption
• There is a need for incentives for homebuilders,
homeowners, and businesses to invest in solar.
• Money taken off other bills for selling your excess
power back to the city.

50. Local
• Manufacturers
• Examples of solar technology
– Large (PV’s)
– Small, examples
• Solar powered sensor light
• Solar powered rechargeable battery
• Solar cookers

51. Why Solar?
Solar Energy can benefit the US by:
reduce our dependence on imported fuels
stimulate our economy by creating jobs in the
manufacturing and installation of solar energy
systems
diversify our energy supply
offset greenhouse gas emissions