SOLAR POWER
BECHELOR OF TECHNOLOGY IN MECHANICAL ENGINEERING SUBMITTED BY: ABHISHEK MISHRA PRABHAKAR MISHRA ANIL KUMAR UPADHYAY
NAVKARAN SINGH JULKA
UNDER THE SUPERVISION OF: MR. N.G.P.MURTY
SOLAR POWER
AN ENERGY ALTERNATIE
INTRODUCTION
Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power . Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Photovoltaics convert light into electric current using the photoelectric effect.
DEVELOPMENT AND DEPLOYMENT
The early development of solar technologies starting in the 1860s was driven by an expectation that coal would soon become scarce. However, development of solar technologies stagnated in the early 20th century in the face of the increasing availability, economy, and utility of coal and petroleum. In 1974 it was estimated that only six
private homes in all of North America were entirely heated or cooled by functional solar power systems. The 1973 oil embargo and 1979 energy crisis caused a reorganization of energy policies around the world and brought renewed attention to developing solar technologies.Deployment strategies focused on incentive programs such as the Federal Photovoltaic Utilization Program in the US and the Sunshine Program in Japan.
OPERATIONAL SOLAR THERMAL POWER STATIONS
Capacity (MW) 354 Name Solar Energy Generating Systems Solnova Solar Power Station Andasol solar power station Nevada Solar One Country Location Mojave Desert California Seville Notes Collection of 9 units Completed 2010
USA
150
Spain
100
Spain
Granada Boulder City, Nevada
Completed 2009
64
USA
50
Ibersol Ciudad Real
Spain
Puertollano, Ciudad Real
Completed May 2009
PHOTOVOLTAICS
Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material. Materials presently used for photovoltaics include
monocrystallinesilicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and copper indium gallium selenide/sulfide. Due to the growing demand for renewable energy sources, the manufacturing of solar cells and photovoltaic arrays has advanced considerably in recent years.
PHOTOVOLTAIC EFFECT
The photovoltaic effect is the creation of a voltage (or a corresponding electric current) in a material upon exposure to light. Though the photovoltaic effect is directly related to the photoelectric effect, the two processes are different and should be distinguished.In the photoelectric effect, electrons are ejected from a material's surface upon exposure to radiation of sufficient energy. The photovoltaic effect is different in
that the generated electrons are transferred between different bands (i.e., from the valence to conduction bands) within the material, resulting in the buildup of a voltage between two electrodes.
In most photovoltaic applications the radiation is sunlight and for this reason the devices are known as solar cells. In the case of a p-n junction solar cell, illuminating the material creates an electric current as excited electrons and the
remaining holes are swept in different directions by the built-in electric field of the depletion region
ENERGY STORAGE METHODS
Solar energy can be stored at high temperatures using molten salts. Salts are an effective storage medium because they are lowcost, have a high specific heat capacity and can deliver heat at temperatures compatible with conventional power systems. The Solar Two used this method of energy storage, allowing it to store 1.44 TJ in its 68 m³ storage
tank, enough to provide full output for close to 39 hours, with an efficiency of about 99%.
Off-grid PV systems have traditionally used rechargeable batteries to store excess electricity. With grid-tied systems, excess electricity can be sent to the transmission grid. Net metering programs give these systems a credit for the electricity they deliver to the grid. This credit
offsets electricity provided from the grid when the system cannot meet demand, effectively using the grid as a storage mechanism. Credits are normally rolled over month to month and any remaining surplus settled annually. Pumped-storage hydroelectricity stores energy in the form of water pumped when surplus electricity is available, from a lower elevation
reservoir to a higher elevation one. The energy is recovered when demand is high by releasing the water: the pump becomes a turbine, and the motor a hydroelectric power generator. Artificial photosynthesis involves the use of nanotechnology to store solar electromagnetic energy in chemical bonds, by splitting water to produce hydrogen fuel or then combining
with carbon dioxide to make biopolymers such as methanol. Many large national and regional research projects on artificial photosynthesis are now trying to develop techniques integrating improved light capture, quantum coherence methods of electron transfer and cheap catalytic materials that operate under a variety of atmospheric conditions.
SOLAR CELL
A solar cell (also called photovoltaic cell or photoelectric cell) is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect. Assemblies of cells used to make solar modules which are used to capture energy from sunlight, are known as solar panels. The energy generated from these solar
modules, referred to as solar power, is an example of solar energy. Photovoltaics is the field of technology and research related to the practical application of photovoltaic cells in producing electricity from light, though it is often used specifically to refer to the generation of electricity from sunlight.
PERFORMANCE
Temperature
Generally, as with other semiconductor devices, temperatures above room temperature reduce the performance of photovoltaics.
Optimum orientation of solar panels
For best performance, terrestrial PV systems aim to maximize the time they face the sun. Solar
trackers aim to achieve this by moving PV panels to follow the sun. The increase can be by as much as 20% in winter and by as much as 50% in summer. Static mounted systems can be optimized by analysis of the sun path. Panels are often set to latitude tilt, an angle equal to the latitude, but performance can be improved by adjusting the angle for summer or winter.
EFFICIENCY
The efficiency of a solar cell may be broken down into reflectance efficiency, thermodynamic efficiency, charge carrier separation efficiency and conductive efficiency. The overall efficiency is the product of each of these individual efficiencies.
Due to the difficulty in measuring these parameters directly, other parameters are measured instead: thermodynamic efficiency, quantum efficiency, integrated quantum efficiency, VOC ratio, and fill factor. Reflectance losses are a portion of the quantum efficiency under "external quantum efficiency". Recombination losses make up a portion of the quantum efficiency, VOC ratio, and fill factor. Resistive losses are predominantly categorized under fill factor, but
also make up minor portions of the quantum efficiency, VOC ratio. Crystalline silicon devices are now approaching the theoretical limiting efficiency of 29%.
APPLICATIONS
Power stations In buildings In transport Standalone devices Rural electrification Solar roadways Solar Power satellites
SOLAR ENERGY COMPANIES IN INDIA
1 Tata BP Solar India No Ltd Sun Technics Energy No Systems Pvt Ltd Bharat Heavy Yes Electricals Ltd HHV Solar Yes Technologies Pvt Ltd Emmvee Toughened Glass & Photovoltaics No Pvt Ltd Yes
2
Yes
3
Yes
4
Yes
5
Yes
6
IComm Tele Ltd
No
Yes
7
Thrive Energy No technologies (I) Ltd
Yes
8
Photon Systems Ltd
Energy
No
Yes
9
Andromeda Energy No Technologies (P) ltd Noble Energy Solar No Technologies Ltd XL Telecom & Energy No Ltd Sungrace Energy No Solutions Pvt Ltd
Yes
10
Yes
11
Yes
12
Yes
13
Shurjo Energy
No
Yes
14 15
Synergy Energy
Renewable
No No
Yes Yes
Sova Power Limited
16
Vikram Solar Pvt. Lt
No
Yes
ADVANTAGES
The 89,000 TW of sunlight reaching the Earth's surface is plentiful – almost 6,000 times more than the 15 TW equivalent of average power consumed by humans. Additionally, solar electric generation has the highest power density (global mean of 170 W/m²) among renewable energies.
Solar power is pollution-free during use. Production endwastes and emissions are manageable using existing pollution controls. End-of-use recycling technologies are under development and policies are being produced that encourage recycling from producers. PV installations can operate for many years with little maintenance or intervention after their initial set-up, so after the initial capital cost of building
any solar power plant, operating costs are extremely low compared to existing power technologies.
DISADVANTAGES
Solar electricity production depends on the limited power density of the location's insolation. Average daily output of a flat plate collector at latitude tilt in the contiguous US is 3–7 kilowatt·h/m²/day and on average lower in Europe.
Solar electricity is more expensive than most other forms of small-scale alternative energy production. Without governments mandating "feed-in tariffs" for green solar energy, solar PV is less affordable to homeowners than solar hot water or solar space heating. Much of the investment in a home-mounted system may be lost if the home-owner moves and the buyer puts less value on the system than the seller.