CHAPTER 5 RENEWABLE ENERGY SYSTEMS. SOLAR ENERGY Introduction Renewable energy is generally defined as energy that comes from resources which are naturally replenished on a human timescale such as sunlight, wind, rain, waves and geothermal heat. Wind, solar, and biomass are three emerging renewable sources of energy. Renewable energy can basically be classified in three categories: renewables for transport, renewables for electricity and renewables for heat. In international public opinion surveys there is strong support for promoting renewable sources such as solar power and wind power. At the national level, at least 30 nations around the world already have renewable energy contributing more than 20 percent of energy supply.* *REN21, the Renewable Energy Policy Network for the 21st Century: "Renewables global futures report 2013“ Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 2 Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 3 Solar Energy Solar power has a long historyasenergysourcefor humans. For example, solar power was used for heating of water in the Roman empire. A steam engine based on solar power was constructed by Auguste Mouchout in 1861, but was found to be far too expensive to have a commercial value. Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 4 The Earth receives 174 petawatts (PW) of incoming solar radiation (insolation) at the upper atmosphere. Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 5 The Sun and Radiation • The sun 1.4 million km in diameter 3.8 x 1020 MW of radiated electromagnetic energy Energy from the sun in the form of ultra‐violet, visible and infra‐red electromagnetic radiation is known as solar radiation. Insolation (from Latin insolare, to expose to the sun) is the total amount of solar radiation energy received on a given surface area during a given time. It is also called solar irradiation and expressed as "hourly irradiation" if recorded during an hour or "daily irradiation" if recorded during a day. Practitioners in the business of solar energy may use the unit watt‐ hour per square meter (Wh/m2). If this energy is divided by the recording time in hours, it is then a density of power called irradiance, expressed in watts per square meter (W/m2). The intensity of energy arriving from the sun in space just outside the earth’s atmosphere is approximately 1367 W/m2, called the solar constant. Although it is termed a “constant,” it varies over time. Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 6 Average insolation, or solar energy reaching a given location on earth, will be lower than the amount available outside the atmosphere due to absorption and diffraction of sunlight in the atmosphere, changing weather, loss of sunlight at night, and so on. Worldwide average values for some representative cities, taking all these factors into account, range between 100 W/m2 for Glasgow, Scotland, and 280 W/m2 for Cairo, Egypt. Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 7 Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 8 Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 9 Solar Insolation I0 I0 depends on distance between earth and sun and on intensity of the sun. Ignoring sunspots, I0 can be written as 360n 2 I0 SC 1 0.034cos (W/m ) 365 SC = solar constant = 1.377 kW/m2 n=daynumber(January1isday1;December31isday365). n is also called the “Julian date,” from the Julian calendar Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 10 Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 11 Solar Declination Solar declination δ – the angle formed between the plane of the equator and the line from the center of the sun to the center of the earth δ varies between +/‐ 23.45˚ Assuming a sinusoidal relationship, a365dayyear,andn=81isthe spring equinox, the approximation of δ for any day n can be found from: 360 23.45sinn 81 365 Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 12 Altitude Angle and Azimuth Angle Altitude Angle Azimuth Angle http://www.pveducation.org/pvcdrom/properties‐of‐sunlight/azimuth‐angle Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 13 Solar Basic Processes Three processes have been implemented in practice to transform the solar radiations into energy: Solar photovoltaics (PV), passive solar power (PSP) and concentrated solar power (CSP). Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 14 Solar photovoltaics (PV) Solar Cells Background 1839 ‐ French physicist A. E. Becquerel first recognized the photovoltaic effect. Photo+voltaic = convert light to electricity 1883 ‐ first solar cell built, by Charles Fritts, coated semiconductor selenium with an extremely thin layer of gold. 1956 ‐ Bell Laboratories, experimenting with semiconductors, accidentally found that silicon doped with certain impurities was very sensitive to light. Daryl Chapin, Calvin Fuller and Gerald Pearson, invented the first practical device for converting sunlight into useful electrical power. Resulted in the production of the first practical solar cells with a sunlight energy conversion efficiency of around 6%. 1958 ‐ First spacecraft to use solar panels was US satellite Vanguard Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 15 “Bell System Solar Battery Converts Sun’s Rays into Electricity”, Advertisement from Look Magazine, 1956. Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering The solar cells in the early 1950s were about 0.5 % efficient. Today a module is about 20 % efficient. A 1 kW system: . In 1950 = 2,400 square feet . In 2005 = 80 Square feet Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 17 Annual output of world PV manufacturing and average cost per rated watt of panels, 1975 to 2003. Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering Global Cumulative PV Power http://www.epia.org/fileadmin/EPIA_docs/publications/epia/Global_Market_Outlook_Until_2013.pdf Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering Cumulative installed solar electric power by 2007 1st Germany 3.8 GW 2nd Japan 1.9 GW 3rd US 814 MW 4th Spain 632 MW Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering World's largest photovoltaic (PV) power plants (12 MW or larger) Name of PV power plant Country DC GW·h Notes Peak /year Power (MW) Olmedilla Photovoltaic Park Spain 60 85 Completed September 2008 Puertollano Photovoltaic Park Spain 50 2008 Moura photovoltaic power station Portugal 46 93 Completed December 2008 Waldpolenz Solar Park Germany 40 40 550,000 First Solar thin-film CdTe modules. Completed Dec 2008 Arnedo Solar Plant Spain 34 Completed October 2008 Merida/Don Alvaro Solar Park Spain 30 Completed September 2008 17 more Spain Avg 20 2 more Korea Avg 20 Koethen Germany 14.75 13 200,000 First Solar thin-film CdTe modules. Completed Dec 2008 Nellis Solar Power Plant USA 14.02 30 70,000 solar panels Planta Solar de Salamanca Spain 13.8 n.a. 70,000 Kyocera panels 6 more Spain, 1 US, 1 Germany Avg 12 http://en.wikipedia.org/wiki/Photovoltaic_power_stations Germany 10,000 companies, including installers work in solar PV 80 companies are cell and module makers 42,000 employees Sales were $5.7 B including $2.5 B in exports The ‘feed‐in’ tariff 2008 German utilities pay $0.47 to $0.68/kWh depending on type and size of system for new solar systems www.epia.org Solar Generation V Report Sep 2008 Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering Waldpolenz Solar Park The Waldpolenz Solar Park is built on a surface area equivalent to 200 soccer fields, the solar park will be capable of feeding 40 megawatts into the power grid when fully operational in 2009. http://www.dw-world.de/dw/article/0,2144,3430319,00.html Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering Waldpolenz Solar Park http://lumbergusa.com/main/Bild/sp_pv_07/Brandis-Waldpolenz-Fotomont.jpg Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering The Major PV Cell/Module Manufacturers Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 26 Photovoltaic (PV) Hierarchy Cell < Module < Panel < Array Overview of PV Function How PV cells work: A photovoltaic cell can convert sunlight into DC current. The working principle of photovoltaic cell is largely depending on the characteristic of a semiconductor. A semiconductor consists of two types of materials which are p‐type silicon and n‐type silicon these two made up the internal circuit. Due to this characteristic, light of specific wavelength will be able to ionize the atom in the silicon. This causes the electron to move freely and is pulled towards the n‐type semiconductor and the holes produced will move to the p‐ type semiconductor this is called photovoltaic