What is solar energy? Putting solar energy in use - Solar Heating Systems - Power towers - Parabolic Dishes and Troughs - Photovoltaic cells (solar cells) - Solar Ponds “Solar Tuki” – a clean alternative to “wicked” kerosene lamp (case study) Advantages and Disadvantages of solar energy Conclusion
Photovoltaic (solar) panel Originates with the thermonuclear fusion reactions occurring in the sun. Clean, renewable source of energy Harnessed by solar collection methods such as solar cells Converted into usable energy such as Sun and electrical power lines electricity Set of solar panels
Represent the entire electromagnetic radiation (visible light, infra red, ultraviolet, x-rays and radio waves). The greatest output of solar energy is the visible part of spectrum i.e. 43%
Solar power systems installed in the areas defined by the dark disks could meet the worlds current total energy demand
1. Solar Heating Systems- Two types;a) Active solar heating system- that uses pumps or blowers toactively circulate the air or water from the collector to desiredlocation. Example: Active system with water heated by solar collector and used to supplement hot water
Solar water heating system:Efficiency of solar heating system is always less than100% because; a) % transmitted depends on angle of incidence, b) number of glass sheets (single glass sheet transmits 90- 95%) c) composition of the glassSolar water heating saves approx. 1000 megawatts ofenergy a yr., equivalent to eliminating the emissionsfrom two medium sized coal burning power plant.By using solar water heating over gas water heater, afamily will save 1200 pounds of pollution each year.
b) Passive solar heating system- relies on natural convection current to move the air or water. Passive solar Passively heated at Colorado
Heating living spaces:Best design of a building is for it to act as a solar collectorand storage unit. This is achieved through three elements:insulation, collection, and storage.Efficient heating starts with proper insulation on externalwalls, roof, and the floors. The doors, windows, and ventsmust be designed to minimize heat loss.Collection: south-facing windows and appropriatelandscaping.Storage: Thermal mass—holds heat. a) Water= 62 BTU per cubic foot per degree F. b) Iron=54, Wood (oak) =29, Brick=25, concrete=22, and loose stone = 20.
1. Power towers: Power tower in Barstow, California
Power towers….General idea is to collect the light from many reflectors spread over a large area at one central point to achieve high temperature. (like magnifying glass to focus sunlight onto a tiny spot to burn a hole through a piece of paper)The intense heat generates steam from boiler to drive aconventional turbo generator.Example is the 10-MW solar power plant in Barstow, CA. • 1900 heliostats, each 20 ft by 20 ft • a central 295 ft tower
Parabolic Dishes and Troughs…..Focus sunlight on a smaller receiver for each device; theheated liquid drives a steam engine to generate electricity.Typically, the reflector is made of thick glass silvermirrors formed into the shape of a parabola.Because they work best under direct sunlight, parabolicdishes and troughs must be steered throughout the day inthe direction of the sun.The first of these Solar Electric Generating Stations (SEGS)was installed in California by an Israeli company, LuzInternational.Output was 13.8 MW; cost was $6,000/peak kW andoverall efficiency was 25%.
Silicon Photovoltaic cells (solar wafer cells) are capable of directly converting sunlight into electricity. Solar Solar cell is an electrical cells component that work based on photovoltaic effect. A simple wafer of silicon with wires attached to the layers. Current is produced based on types of silicon (n- and p- types) used for the layers. Each cell=0.5 volts.
Working of PV cell:A PV cell consists of two thin layers of semi-conducting material. The lower layer hasatoms with valence electron; such electronsare easily lost. This is the “p-layer”. Theupper layer has atoms lacking valanceelectrons; such materials easily gainelectrons. This is the “n-type” layer.When photons strike a PV cell, their energyis transferred to an electron in thesemiconductor material of the cell.so-called p-n-junction is created onthe barrier layer. The special featureof this barrier layer is that a strongelectrical field is created locally.
Solar Panel Use Today Tele com Residential Home Systems (2-8 kW
Solar ponds…….One way to tap solar energy is through the use ofsolar ponds. Solar ponds are large-scale energycollectors with integral heat storage for supplyingthermal energy. It can be use for variousapplications, such as process heating, waterdesalination, refrigeration, drying and powergeneration.The 6000-square-metre solar pond in Bhuj, the firstlarge-scale pond in industrial environment to cater toactual user demand, supplied totally about 15 millionlitres of hot water to the dairy at an averagetemperature of 75°C between September 1993 andApril 1995.
Working of solar pond:The solar pond works on a very simple principle. It is well-known that water or air is heated they become lighter and riseupward. Similarly, in an ordinary pond, the sun’s rays heat thewater and the heated water from within the pond rises andreaches the top but loses the heat into the atmosphere. The netresult is that the pond water remains at the atmospherictemperature. The solar pond restricts this tendency by dissolvingsalt in the bottom layer of the pond making it too heavy to rise.
It consist of :- - 2 sets of 0.3-Watt White Light Emitting Diode (WLED) based lamp - 1 unit of 3 Watt Solar photovoltaic panel. - Built-in rechargeable batteries Aim was to displace kerosene wicked lamps by solarphoto voltaic based on household lightingsystem (known as Solar Tuki) through theintegrated approach of communitymobilization and technologicalintervention.
Solar Tuki… Developed by ECCA (Environmental Camps for Conservation Awareness), an NGO- 2004, Piloting in 100 households January 2005, “Light for All” campaign initiated 2007, Tech Museum Awards (category Economic Development)(for Solar Tuki), The Tech Museum of Innovation, California, USA In addition to be a rechargeable lighting system, it is also used as a power station for radios. This device is relatively costly (50 US$), it is therefore proposed in leasing or rental systems. This concept and technology, already successfully used in Nepal, are proposed to be tested in Africa during the field tests In partnership with Selco and Antenna Technologies.ECCA-Nepal Solar Tuki movie clipwww.youtube.com/watch?v=q1LjRcVygjg
1.Saves you moneya) After the initial investment has been recovered, the energy from the sun is practically free.b) Solar energy does not require any fuel. Its not affected by the supplyand demand of fuel and is therefore not subjected to the ever-increasingprice of gasoline.c) The savings are immediate and for many years to come.d) The use of solar energy indirectly reduces health costs.2. Environmentally friendlya) Solar Energy is clean, renewable (unlike gas, oil and coal) andsustainable, helping to protect our environmentb) It does not pollute our air by releasing carbon dioxide, nitrogen oxide,sulphur dioxide or mercury into the atmosphere like many traditional formsof electrical generations does
c) Therefore Solar Energy does not contribute to global warming, acidrain or smog.d) By not using any fuel, Solar Energy does not contribute to the costand problems of the recovery and transportation of fuel or thestorage of radioactive waste3. Independent/ semi-independenta) A Solar Energy system can operate entirely independent, not requiring aconnection to a power or gas grid at all. Systems can therefore beinstalled in remote locations (like holiday log cabins), making it morepractical and cost-effective than the supply of utility electricity to a newsite.4. Low/ no maintenancea) Solar Energy systems are virtually maintenance free and will last fordecades.b) Once installed, there are no recurring costsc) They operate silently, have no moving parts, do not release offensivesmells and do not require you to add any fuel
a) The initial cost is the main disadvantage of installing a solarenergy system, largely because of the high cost of thesemi-conducting materials used in building one.b) Solar panels require quite a large area for installation toachieve a good level of efficiency.c) The efficiency of the system also relies on the location ofthe sun, although this problem can be overcome with theinstallation of certain components.d) The production of solar energy is influenced by thepresence of clouds or pollution in the aire) Similarly, no solar energy will be produced duringnighttime although a battery backup system will solve thisproblem.
Argument that sun provides power only during the day is countered by the fact that 70% of energy demand is during daytime hours. At night, traditional methods can be used to generate the electricity. Goal is to decrease our dependence on fossil fuels. Mitigates the effects of acid rain, carbon dioxide, and other impacts of burning coal and counters risks associated with nuclear energy. pollution free, indefinitely sustainable. Innovation like Solar Tuki is important because it can be useful for those rural life which are faraway from main power lines.