Solar Power An introduction to the history, technologies, policy applications and future of solar power.
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]
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.
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.
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.
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]
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.
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.
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?
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
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
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.
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
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]
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]
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 Tyler Hanson
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 What is Active Solar
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 Tyler Hanson
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.
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!! Tyler Hanson
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. Tyler Hanson 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.
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) Tyler Hanson
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 • Direct Gain- sunlight directly enters the space it is intended to heat, and is stored and released in that area. • Indirect gain- Trombie Walls • Isolated Gain- sun rooms • Heating • Lighting Tyler Hanson
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.
Solar Home Design • In thenorthern 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.
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.
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.
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.
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.
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.
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
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
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.
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 ProjectContact: Mary SpruillNEED ProjectPO Box 10101Manassas, VA 20108TEL: (703) 257-1117FAX: (703) 257-0037EMAIL: email@example.comWEB: www.need.org
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
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
County Examples • El Paso Solar Energy Association • Solar San Antonio, Inc. • North Texas Renewable Energy Group http://www.txses.org/ntreg.php
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.
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.
NTREG • The TXSES chapter in the Dallas-Fort Worth area is called the North Texas Renewable Energy Group, or "NTREG". They maintain a discussiongroup athttp://groups.yahoo.com, named "ntreg",and schedule regular meetings. For more information, please join the discussion group or contact Mike Correale.
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/
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.
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.
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,
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.
Local • Manufacturers • Examples of solar technology • Large (PV’s) • Small, examples • Solar powered sensor light • Solar powered rechargeable battery • Solar cookers