The document provides an overview of solar power technologies, highlighting the differences between active and passive solar systems, as well as their applications in residential architecture and urban planning. It details the history and advancements in photovoltaic (PV) technologies, including the rise of solar installations in various countries, alongside the economics and efficiency of different solar power systems. Additionally, it discusses innovative heat storage solutions and the integration of solar and wind energy to address intermittencies.

1. An Introduction to Solar Power Prepared for www.philazine.com by Philip Woodard – 2009 – all rights reserved ©

2. World’s Largest Solar Plant Olmedilla Photovoltaic Park, Spain 162,000 flat solar photovoltaic panels 60 megawatts of electricity C ompleted in 15 months at a cost of about $530 million

3. Passive or Active Depends on the way sunlight is captured, converted and distributed Active solar techniques use photovoltaic panels, pumps, mirrors, troughs, and fans to convert sunlight into useful outputs Passive solar techniques include selecting materials to store heat directly, designing spaces to naturally circulate air, and positioning buildings for most sunlight

4. Passive Solar -- Architecture Passive systems use natural energy from the sun to heat a building Heating and cooling account for 30% of the energy used in commercial buildings and 50% of the energy used in residential buildings Use mass (concrete slabs, tile, masonry and extra-thick drywall or plaster) to absorb and re-radiate solar heat in the occupied spaces Use circulating air to cool Cheaper than active systems because they are less susceptible to malfunction – reduces energy costs 50% to 90% They rely on nature, rather than using mechanical equipment to produce energy

5. Passive Solar -- Architecture Position building and windows for most Sunlight Choose compact proportion (a low surface area to volume ratio) Select shading and overhangs Use sunlight to light interiors and replace artificial lighting for lower temperatures and less air conditioning Tailor these to local climate and environment to produce well-lit spaces that stay in a comfortable temperature range Use active solar equipment such as pumps, fans and switchable windows to complement passive design and improve system performance

6. Passive Solar -- City Planning Cities can be urban heat islands with higher temperatures than the the surrounding environment night-time temperatures raised more than daytime temperatures The higher temperatures come from increased absorption of the Sunlight by urban materials such as asphalt and concrete city climates can influence on plant growing seasons up to 10 kilometers (6 miles) away from city edges Counteract the increase temperatures by paint-ing buildings and roads white and planting trees One Los Angeles program should reduce summer temperatures by about 3 °C at an estimated cost of US $1 billion, giving estimated total annual benefits of US $530 million from reduced air-conditioning costs and healthcare savings

7. Active Solar -- Photovoltaics A solar power technology that generates electricity (direct current) using semiconductors called solar cells The photovoltaic effect comes when sunlight hits a PV panel; it releases electrons from special layers of silicon and pushes them across an electric field The first solar cell was constructed by Charles Fritts in the 1880s Researchers Gerald Pearson, Calvin Fuller, and Daryl Chapin created the silicon solar cell in 1954

8. Active -- Photovoltaics Earliest applications came from U.S. space program, PVs were used as a back-up power source to the Vanguard satellite in 1958 which allowed for continued transmitting a year after its chemical battery was exhausted A number of solar cells form a solar "Module" or "Panel“ which can then be combined to make solar systems ranging from a few watts of electricity output to multi megawatt power stations Yearly growth in the solar photovoltaics 2003 to 2008 has averaged more than 40%

9. Falling Costs By the 1970s falling prices made PV generation competitive in remote areas without grid access Early terrestrial uses included telecom-munication stations, off-shore oil rigs navigational buoys and railroad crossings Off-grid applications accounted for over half of worldwide installed capacity until 2004 Prices fell from US $100.00 per watt in 1971 to US $7.00 watt in 1985 First Solar, the largest manufacturer of thin panels, claims its products will generate electricity in sunny countries as cheaply as large power stations by 2012 8.1

10. Falling Costs – Part Two Lawrence Berkeley National Laboratory researchers surveyed the costs of 37,000 photovoltaic systems in the U.S. Average price of installation fell from $10.50 per watt in 1998 to $7.60 per watt in 2007 9.1

11. Solar vs Nuclear 11.1 55 months 16 months Construction time $1.91 $53.77 Cost – Actual Watt $1.76 / Wp $8.95 / Wp Cost – Watt of Capacity $1.76 billion $0.54 billion Total Cost 0.92 0.17 Capacity Use 8108 GWh / yr 88 GWh / year Net generation 8793 GWh / yr 528 GWh / yr Capacity 2005 2008 Year Pressurized light-water Silicon photo-voltaic (PV) Type Uljin, South Korea Olmedilla de Alarcón, Spain Location

12. Photovoltaic Leaders Between 1992 and 1994 Japan increased R&D funding, established metering guidelines, and encouraged installations of residential PV systems with subsidies Japan’s PV installations climbed from 31.2 MW in 1994 to 318 MW in 1999 Germany has become the leading PV market: Installed PV capacity has risen from 100 MW in 2000 to approximately 4,150 MW at the end of 2007 Spain has become the third largest PV market after using Germany’s subsidy plans Spain Installed more than 3,000 megawatts of photovoltaic power in 2007, making it the world’s biggest market for that kind of solar power Spain increased solar capacity by a factor of 5.4 8.1

13. U.S. Installations Rising In American Southwest, there was a 78% jump in applications to build solar projects on federal land in 2008 Applications have risen to 223 from 125 107 applications for the BLM land in California 71 applications in Nevada 35 in Arizona New Mexico, Utah and Colorado make up the rest Overall U.S. grid-connected PV capacity is about 800 MW Top states for PV panels tied to the grid are California with 530.1 MW, New Jersey with 70.2 MW, Colorado with 35.7 MW and Nevada with 33.2 MW

14. Germany’s Gut Erlasee Solar Park A 12-megawatt facility located amid cropland near the Bavarian town of Arnstein Panels tilt and rotate to stay facing the sun throughout the day

15. Thin Film Photovoltaics One venture capitalist says most thin film photovoltaics (PV) advances fail in the transition from the lab to manufacturing due to yield problems and other manufacturing problems 9.1 Have tended to succeed in the lab, but fail in the manufacturing process. Only one or two thin-film projects have brought product to market in 30 years, and it's a US $100M-$200M dollar up-front investment "just to play the game and see if your product really works."

16. Active Solar – Power Tower Solar “power towers” use a large field of sun-tracking mirrors called heliostats that face a central tower They focus the sunlight onto a receiver on its top The intense energy concentrated onto the tower produces temperatures up to 1,500 degrees Celsius (2,732 degrees Fahrenheit That energy then heats up water, producing steam that drives a turbine to produce electricity

17. CSP Systems – How They Work Sandia National Laboratories systems look like giant, highly polished satellite dishes Each dish is a mosaic of 82 mirrors that fit together to form a 38-ft-wide parabola The mirrors’ precise curvature focuses light onto a seven inch area The Heat rises to 1450 F 15.1 That heat runs a Stirling engine to make mechanical energy Hydrogen gas in a Stirling engine’s four 95 cc cylinders expands and contracts as it is heated and cooled, driving pistons to turn a small electric generator. a

18. CSP Systems – Heat Storage Nine CS9 plants with a combined capacity of 354 megawatts have been operating in the Mojave Desert since their construction between 1984 and 1991 An average coal plant produces about 670 Mw The nine Provide power to 500,000 homes Spain is pioneering a way to store solar power A hot liquid can be stored more efficiently than electricity A $5.00 thermos can hold as much energy as heat as a $150.00 laptop battery does as electrochemical Spain has designed two 50-Mw plants that store heat in a giant thermos filled with molten salt

19. New Mexico Plant is U.S. Largest 2009 plans for a 92-megawatt solar thermal plant could produce enough electricity to power 74,000 homes Built and Run by New Jersey-based NRG Energy for El Paso Power Suntower will be built on 450 acres of private land near the Santa Teresa It will look like a giant field of mirrors interspersed with 180-foot towers topped by boilers. Motors on the mirrors will keep them aligned with the sun.

20. Active Solar – CSP Systems Concentrating Solar Power (CSP) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam Auguste Mouchout used a parabolic trough for a solar steam engine in 1866, The concentrated light is then used as a heat source for a conventional power plant A wide range of concentrating technologies exists: solar trough, parabolic dish and solar power tower These methods vary in the way they track the Sun and focus light In all these systems a working fluid is heated by the concentrated sunlight and is then used for power generation or energy storage

21. Active Solar – Solar Troughs Plants like California SEGS use “parabolic troughs,” curved mirrors that focus the energy onto pipes containing circulating oil The fluid absorbs the energy and uses it to heat steam to power a standard generator That drives a turbine to produce electricity

22. Active Solar – Two CSP Systems Solar trough -- linear parabolic reflector concentrates along the reflector's focal line follows sun during the daylight hours by tracking along a single axis best land-use factor of any solar technology The SEGS plants in California Segs Nevada’s Solar One Stand-alone reflectors concentrate light onto a receiver positioned at the reflector's focal point Track Sun along two axes Highest efficiency among CSP technologies Canberra, Australia’s Big Dish

23. Active – Two More CSP Systems Stirling solar dish combines a parabolic concentrating dish with a Stirling Heat Engine (normally used to drive electric generators) higher efficiency of converting sunlight into electricity and longer lifetime solar power tower uses an array of tracking reflectors ( heliostats ) to concentrate light on a central receiver atop a tower less advanced than trough systems but offer higher in efficiency and energy storage California’s Solar Two and Spain’s Sanlucar La Mayor

24. CSP Systems Problems Use four times as much water as a natural gas plant and twice as much as a coal or nuclear plants Since they heat a fluid that boils water to turn a turbine, they produces excess heat They need cooling towers to release heat by evaporation and use much water

25. U.S. -- Best Solar Locations

26. Problems Most of the cost and operational problems associated with alternative energy sources arise from the fact that once the energy is converted to heat or electricity, it has to be used right away or stored at enormous cost and trouble

27. Solar and Wind Synergy In areas where demand for electricity is higher in winter than in summer, wind and solar are complementary High pressure areas tend to bring clear skies and low surface winds Low pressure areas tend to be windier and cloudier Solar energy typically peaks in summer, but often wind energy is lower in summer and higher in winter The intermittencies of wind and solar power can somewhat offset each other

28. Endnotes 8.1 Chris Goodall , “The 10 big energy myths,” The Guardian, April 7, 2008 BACK 9.1 David Baker, “Cost of Solar has Fallen in Decade,” San Francisco Chronicle, February 20, 2009 BACK 11.1 “http://uvdiv.blogspot .com/2009/07/test.html,” July, 2009 BACK 15.1 Alex Hutchinson, “Solar Thermal Power May Make Sun-Powered Grid a Reality,” Popular Mechanics , February, 2009 BACK