1. SOLAR PHOTOVOLTAIC CELl
Presentation on
SOLAR PHOTOVOLTAIC CELl

2. What is a solar cell?
Solid state device that converts incident solar energy directly into electrical energy
Efficiencies from a few percent up to %
No moving parts
No noise
Lifetimes of years or more

3. PHOTOVOLTAIC EFFECT
The PHOTOVOLTAIC EFFECT refers to photons of light exciting electrons into a higher state of energy, allowing them to act as charge carriers for an electric current
The term “Photovoltaics” comes from the Greek, meaning light, volts, and electrical

4. Solar Cells History
French physicist A. E. Becquerel first recognized the photovoltaic effect
Photo+voltaic = convert light to electricity
Bell Laboratories, experimenting with semiconductors, accidentally found that silicon doped with certain impurities was very sensitive to light.
Resulted in the production of the first practical solar cells with a sunlight energy conversion efficiency of around 6%.

5. 1958 - First spacecraft to use solar panels was US satellite Vanguard 1

6. How Does It Work?
The junction of dissimilar materials (n and p type silicon) creates a voltage
Energy from sunlight knocks out electrons, creating a electron and a hole in the junction
Connecting both sides to an external circuit causes current to flow
In essence, sunlight on a solar cell creates a small battery with voltages typically 0.5 v. DC

7. How Does It Work?

8. Semiconductor material
A semiconductor is a material which has electrical conductivity between that of a conductor such as copper and an insulator such as glass.
Silicon(Si) ,Germenium(Ge)

9. Types of Semiconductor
Intrinsic Semiconductor
Extrinsic Semiconducter
P - Type
N- Type

10. Intrinsic Semiconductor
Also called an undoped semiconductor or i- type semiconductor, is a pure semiconductor without any significant dopant species present.
Number of excited Electrons Holes are equal

11. Extrinsic Semiconductor
In semiconductor production, doping in tentionally introduces impurities into an extremely pure semiconductor for the purpose of modulating its electrical properties
Based on impurties 2 types of semiconductor are produced
n- Type
p- type

12. N-type Semiconductor
The pure silicon is doped with a group 5 element such as phosphorus, antimony or arsenic.

13. P-type Semiconductor
The pure silicon is doped with a group 3 element such as boron, aluminium or indium.

14. Solar Cell

15. Types of Solar cell Monocrystalline Solar cell
On the basis of Active Material
Monocrystalline Solar cell
Polycrystalline Solar cell
Amorphous Silicon Solar cell
Gallium Arsenide Cell
Copper Indium Diselenide (CIS) cell
Cadmium Telluride Cell(CdTe)
Organic Photovoltaic Cell

16. 1. Mono Crystal Silicon Cell
Silica (SiO2) is the compound used to make the cells. It is first refined and purified, then melted down and re- solidified so that it can be arranged in perfect wafers for electric conduction. These wafers are very thin.
Many of these types of cells are joined together to make arrays, the size of each array is dependant upon the amount of sunlight in a given area.

17. Mono crystalline Solar Cell
Efficiency
Currently, SunPower (USA) manufacturers the most efficient monocrystalline solar panels - with an efficiency of 22.5 percent

18. Fabriation:
MGS: Raw material is Quartzite (SiO2, sand), then refined to Metallurgical Grade Silicon (MGS)
with coal / coke and ~ 2000°C
2 C (solid) + 2 SiO2(solid) Si (liquid) + 2 CO
Significant power needed: ~ 13 kWh/kg
End result: 98% Silicon
Electronic Grade Silicon (EGS)
MGS + HCl (gas) SiH4 (silane) SiCl4 (silicon tetracloride) SiHCl3(trichlorosilane)

20. Process
High-purity, semiconductor grade silicon is melted in a crucible
Dopant impurity atoms such as boron or phosphorus can be added to the molten silicon in precise amounts to dope the silicon, thus changing it into p- type or n-type silicon, with different electronic properties
A precisely oriented rod-mounted seed crystal is dipped into the molten silicon. The seed crystal's rod is slowly pulled upwards and rotated simultaneously

21. Cont…
By precisely controlling the temperature gradients, rate of pulling and speed of rotation, it is possible to extract a large, single-crystal, cylindrical ingot from the melt
Occurrence of unwanted instabilities in the melt can be avoided by investigating and visualizing the temperature and velocity fields during the crystal growth process

23. Advantages
Durable/Longevity: Several of the early modules installed in the 1970's are still producing electricity today
Drop in Efficiency is just 0.5% per year
More efficient than poly crystalline and thin film solar cell
Lower Installation Costs
Embodied Energy: less embodied energy reqired for per watt of energy
More Electricity for per square area

24. Disadvantages Initial Cost Fragile: it can be damaged by strong wind

25. 2. Polycrystalline solar cell
Polycrystalline (sometimes also called multicrystalline) solar panels are the most common because they are often the least expensive
Polycrystalline silicon is composed of many smaller silicon crystal fused together
A polycrystalline silicon rod made by the Siemens process

26. How it made?
The molten silicon is poured into a cast instead of being made into a single crystal
In the cast process, silicon pieces are melted in a ceramic crucible and then formed in a graphite mold to form an ingot.
Although molding and using multiple silicon cells requires less silicon and reduces the manufacturing costs, it also reduces the efficiency of the solar panels.

27. Methods: 1. P-n junction cells
For a p - n junction cell, a polycrystalline silicon film is deposited by chemical vapor deposition on substances like glass, silicon and metal

28. 2 Metal insulator Semiconductor (MIS) Cells These are made by inserting a thin insulating layer of SiO2 between metal and semiconductor

29. 3. conducting oxide insulator semiconductor Cells
A window semiconductor is used over an active semiconductor
It has high transmittance for solar rdiation and high electricalconductivity
Acts as a antireflection coating

30. Difference b\w Monocrystalline and polycrystalline
The typical monocrystalline solar cell is a dark black colour, and the corners of cells are usually missing as a result of the production process and the physical nature of monocrystalline silicon and Polycrystalline is of light or dark blue colour

31. Differences
Monocrystalline cell is more efficient than polycrystalline polycrystalline panels have an efficiency that is about 70% to 80% of a comparable monocrystalline solar panel.
Polycrystalline cell are less expensive than \monocrystalline

32. 3. THIN FILM TECHNOLOGY
The term "Thin film solar panels" refers to the fact that these types of solar panels use a much thinner level of photovoltaic material then mono-crystalline or multi-crystalline solar panels
Thin film solar cells consist of layers of active materials about 10 nm thick compared with to 300-nm layers for crystalline-silicon cells.
A-Si has been used as a photovoltaic solar cell material for devices which require very little power, such as pocket calculators

33. The thin film solar panel is a new type of solar technology made by coating a metal or glass surface with light absorbing amorphous silicon alloy layers

34. A transparent conducting oxide layer (such as tin oxide) forms the front electrical contact of the cell, and a metal layer forms the rear contact.
The primary objective of manufacturers of these solar panels is to reduce the overall price per watt to make solar competitive
While these thin module prices are much lower in price, they also have a lower module efficiency (roughly 1/2 of monocrystalline solar panels,

35. Amorphous Silicon PV Cells
The most advanced of thin film technologies
Operating efficiency ~6%
Makes up about 13% of PV market

36. Advantages
Versatility: Thin film can be applied to almost all types of surfaces - such as metal, plastic and even paper
Flexibility: While crystal silicon solar panels are rigid and therefore fragile, "thin film" materials can be deposited on flexible substrate materials
Good Performance in Indirect Light
One benefit of thin film solar panels that other types can’t offer is that they don’t suffer a decrease in output when temperatures go up

37. Disadvantages
Efficiency: This is the reason why thin film solar panels haven’t replaced older types yet
Longevity: These cell are not considered as durable as crystalline cell
Scarcity of Raw Tellurium
Toxicity Concerns: Both Cadmium Telluride (larger amounts) and CIGS (smaller amounts) use Cadmium, which is classified as one of the 6th most toxic substance

38. How to make complete Solar cell?

39. Components…
Semiconductor: monocrystalline, Polycrystalline,Thin film Solar cell
Electrical Contacts: Electrical contacts are essential to PV cells because they bridge the connection between the semiconductor material and the external electrical load, such as a light bulb.
Coating on both the side is done. Front side is more complicated.

40. Metals such as palladium/silver, nickel, or copper are used
To make top-surface grids, metallic vapors are deposited on a cell through a mask or painted on via a screen-printing method.
Metals such as palladium/silver, nickel, or copper are used

41. Glass Cover: These are used to protect from atmoshpere
Anti-reflection coatings: The top surface with a thin layer of silicon monoxide (SiO). A single layer reduces surface reflection to about 10%, and a second layer can lower the reflection to less than 4%.
titanium dioxide
silicon oxide,
Glass Cover: These are used to protect from atmoshpere
Encapsulating the cell: in the last finished solar cells are then encapsulated

42. sealed into silicon rubber or ethylene vinyl acetate.
The encapsulated solar cells are then placed into an aluminum frame that has a mylar or tedlar back sheet and a glass or plastic cover
Connectors: Finally, the module is fitted with connectors and cables, so it can be wired.

43. Photovoltaic System
Typical output of a module (~30 cells) is ≈ 15 V, with 1.5 A current

45. How Does A Cell Become A Module?
A solar cell is the basic building block of a PV system.
A typical cell produces .5 to 1V of electricity.
Solar cells are combined together to become modules or if large enough, known as an array.
A structure to point the modules towards the sun is necessary, as well as electricity converters, which convert DC power to AC.
All of these components allow the system to power a water pump, appliances, commercial sites, or even a whole community.

46. Rest of System Components
While a major component and cost of a PV system is the array, several other components are typically needed. These include:
The inverter – DC to AC electricity
DC and AC safety switches
Batteries (optional depending on design)
Monitor – (optional but a good idea)
Ordinary electrical meters work as net meters

47. APPLICATIONS Battery Charging Domestic lighting Street Lighting
Water Pumping
Power Generation Schemes

48. 1. Battery Charging
The PV module charge the battery through an electronic controller
It automatically charge the battery during sunshine and simultaneously supply the power to appliances
During non sun shine it also supply power automatically
Charge controller indicates the charging
In case voltage is below a preset level loads automatically gets cut off

49. Cont…… In case of overcharge, PV cell get disconnected from battery
Short circuit is also provided using fuses
Reverse polarity and indication is also provided

50. Use of Charge controller
A charge controller, charge regulator or battery regulator limits the rate at which current is added to or drawn from electric batteries
It prevents overcharging and may prevent against overvoltage which can reduce battery performance or lifespan, and may pose a safety risk Tracking technology to manufacture our controllers

52. Manufactured by Max Power Point Tracking technology

53. APPICATIONS Street Light Emergency Backup Rural Power Solar Pump
Road Flasher
Solar Lantern
Solar Power Pack
House
Office
Manufacturing Plant

54. 2. DOMESTIC LIGHTING

55. The Power Solar Home Lighting Systems is a prepackaged control unit designed for rural home electrification.
just adds batteries and modules for a complete solar home system that replaces dry cell batteries, kerosene and candles with safe, dependable solar energy
These systems supply electricity for lighting, entertainment and information to homes that are not connected to utility power grids

59. 3. STREET LIGHTING
Solar street lights are powered by photovoltaic cells mounted on the lighting structure
The photovoltaic panels charge a rechargeable battery, which powers a fluorescent or LED lamp during the night.
May be automatic or manually

60. Cont… Standalone solar street lights:
Standalone solar street lights have photovoltaic panels mounted on the structure. Each street light has its own photovoltaic panels and is independent of the other lamps
Centrally operated solar street lights
The photovoltaic panels for a group of street lights are mounted separately and All the street lights in a particular group are connected to this central power source.

61. Our stand alone solar powered lighting offers the following benefits:
eliminates expensive mains cable installation costs
eliminates any associated electricity bills
increases public safety and aids in providing a safe working environment in areas where mains power is difficult to access
fully automatic operation
high quality construction and components
designed for easy servicing and maintenance where required 

62. 4.WATER PUMPING Solar pumping systems work anywhere the sun shines.

63. System Operation
Solar panels mounted on the top of the pole convert sunlight into electricity which is used to charge a battery.
A solar controller/regulator ensures that the battery is charged in the most effective manner and not overcharged. The controller senses when the sun goes down and turns on the light.
The controller can be programmed to run the light all night, or for the required time duration. The controller also protects the battery from over discharge.

65. 1. Water for drinking & cooking 2. Water for livestock
During the hot months, when water requirements are highest, a solar pump will provide a reliable water source for a farm
small pump only running when the sun shines, plus water storage, can often provide all that is requiremed for water supply
1. Water for drinking & cooking
2. Water for livestock
3. Water for crop irrigation

66. 5. SOLAR POWER GENERATION

67. Stand alone PV Power generation
Water pumping
Domestic Lighting
Street Lighting
Grid interactive Power generation
Large Scale power production
Grid is used to Distribute Power

68. Stand alone PV Power generation
These are electrical power systems which are independent of the utility grid

69. Grid interactive Power generation
The availability of grid-interactive PV systems means that energy consumers can tie to the grid when it benefits them and disengage when it does not

70. During day time PV supply power to grid system
On grid means a house remains connected to the state electricity grid. PV module are connected to utility grid system
During day time PV supply power to grid system
During night time or in emergency grid supply power back to the load
Thus need for a battery is removed

71. Advantages The power source of the sun is absolutely free
The production of solar energy produces no pollution. The first and foremost advantage of solar energy is that it does not emit any GHGs
Most systems do not require any maintenance during their lifespan, which means you never have to put money into them
Most systems have a life span of 30 to 40 years
Most systems carry a full warranty for 20 to 30 years or more

72. Cont…
Solar energy offers decentralization in most (sunny) locations, meaning self-reliant societies
The ability to produce electricity off the grid is a major advantage of solar energy for people who live in isolated and rural areas
A particularly relevant and advantageous feature of solar energy production is that it creates jobs.
Solar jobs come in many forms, from manufacturing, installing, monitoring and maintaining solar panels, to research and design, development, cultural integration, and policy jobs

73. Cont…
One of the biggest advantages of solar energy is the ability to avoid the politics and price volatility that is increasingly characterizing fossil fuel markets
Because solar doesn’t rely on constantly mining raw materials, it doesn’t result in the destruction of forests and eco-systems that occurs with most fossil fuel operations

74. Drawbacks
The primary disadvantage to solar energy is the initial cost. Solar energy technologies still remain a costly alternative to the use of readily available fossil fuel technologies
A very common criticism is that solar energy production is relatively inefficient.
solar energy installation requires a large area for the system to be efficient in providing a source of electricity. This may be a disadvantage in areas where space is short, or expensive (such as inner cities)

75. Cont…
Solar energy is only useful when the sun is shining. During the night, your expensive solar equipment will be useless, however the use of solar battery chargers can help to reduce the effects of this disadvantage
The location of solar panels can affect performance, due to possible obstructions from the surrounding buildings or landscape
Pollution can be a disadvantage to solar panels, as pollution can degrade the efficiency of photovoltaic cells
Solar electricity storage technology has not reached its potential yet

77. Payback Time Energy Payback Time:
EPBT is the time necessary for a photovoltaic panel to generate the energy equivalent to that used to produce it.
A ratio of total energy used to manufacture a PV module to average daily energy of a PV system.
At present the Energy payback time for PV systems is in the range
8 to 11 years, compared with typical system lifetimes of around 30 years. About 60% of the embodied energy is due to the silicon wafers.

78. Solar PV Costs
There has been almost six fold decline in price per peak watt of PV module from 1980 to year 2000

79. Battery Sizing I
If your load is 10 kw-hr per day, and you want to battery to provide 2.5 days of storage, then it needs to store 25 kw-hr of extractable electrical energy. Since deep cycle batteries can be discharged up to 80% of capacity without harm you need a baettry with a storage of 25/0.8 = kw-hr. A typical battery at 12 volts and 200 amp-hour capacity stores 2.4 kw-hr of electrical energy

80. Battery Sizing II 31.25 kw-hr/2.4 kw-hr/battery = 13 batteries
The relationship between energy in kw-hr and battery capacity is
E(kw-hr) =capacity(amp-hr) x voltage/1000
E = 200 amp-hr x 12 volts/1000= 2.4 kw-hr
So for kw-hr of storage we need
31.25 kw-hr/2.4 kw-hr/battery = 13 batteries

81. Sizing a PV System to Consumption
A PV system can be sized to provide part or all of your electrical consumption. If you wanted to produce 3600 kw-hr a year at a site that had an average of 4.1 peak sun hours per day,
PV Size in KWp = kw-hr
4.1 kw-hr/day x 365 days/yr x 0.9 x0.98
= 2.7 KWp
Note: the 0.9 is the inverter efficiency and the represents the loss in the wiring.

82. How Much Area Is Needed?
The actual area that you need depends on the efficiency of the solar cells that you use. Typical polycrystalline silicon with around 12% efficiency will require about 100 ft2 of area to provide a peak kilowatt. Less efficient amorphous silicon may need 200 ft2 to provide the same output. Modules are sold in terms of peak wattage and their areas are given so you can easily determine the total roof area that is needed for a given size array.

83. Find the efficiency of a solar cell module given its power rating and its area
Assume it is a 100 Wp module and its area is 0.8 m2. Remember that the peak power rating is based on an intensity of watts/m2. So the maximum output with 100% efficiency is P = I x A = 1000 w/m2 x 0.8 m2 = 800 watts
The actual efficiency = Pactual peak/Pmaximum peak
= 100 watts/800 watts = or 12.5%

84. Global Scenario
Solar Electric Energy demand has grown consistently by 20-25% per annum over the past 20 years (from 26 MW back in 1980 to 127MW in 1997)
At present solar photovoltaic is not the prime contributor to the electrical capacities but the pace at which advancement of PV technology and with the rising demand of cleaner source of energy it is expected by 2030 solar PV will have a leading role in electricity generation
Research is underway for new fabrication techniques, like those used for microchips. Alternative materials like cadmium sulfide and gallium arsenide ,thin-film cells are in development

85. THANK YOU