SOLAR ENERGY TECHNOLOGY

SYLLABUS:

Unit I SOLAR RESOURCES :

Passage through the atmosphere; global distribution; optimal system geometry, Insolation amount available on earth; Resource estimation; Solar data; Solar radiation spectrum; Seasonal and daily variation; Effect of Tilt Angle. Unit II SOLAR PHOTOVOLTAICS:

The Photo Voltaic effect; Spectral response; p-n junction; different types of photovoltaic cells; PV cell characteristics; Effect of variation of temperature; insolation level & tilt angle on the characteristics; equivalent circuits; temperature effects on conversion efficiency; Fabrication and costs of PV cell. Unit III SOLAR THERMAL:

Principles of applied heat transfer, solar

thermal collectors: Glazing, evacuation, selective surfaces, concentrators. Solar thermal applications: water and space heating; solar ponds; dryers; distillation; solar cooker. Passive Solar design. Unit IV SOLAR PHOTOVOLTAIC SYSTEMS:

Photovoltaic modules; module specifications; module hot spots; bypass diodes; PV arrays and PV systems; cabling; earthling and lightning protection. Battery storage: Lead and Nickel cadmium batteries; Charge regulators; LVD circuit; Voltage and current Source Inverters. Tracking Systems; Maximum power point tracking. Unit V SYSTEM APPLICATIONS :

Autonomous PV system; Grid Linked PV systems; Remote application of Photovoltaic’s; System sizing; System Performance; Economics and future prospects.

Text Books:  1. Solar Energy: Principles of Thermal Collection and

Storage by S.P.Sukhatme: TMH 2. Solar Energy Utilization Volume-1 &2 by G.D.Rai-

Khanna Publishers Reference Books: 1. Solar Electricity Handbook-2010 By Micheal Boxwell –

Green Stream publishing 2. Non conventional Energy by G.D.Rai- Khanna Publishers

Unit -I SOLAR RESOURCES

Passage through the atmosphere & global distributionoptimal system geometry Insolation amount available on earth Resource estimation; Solar dataSolar radiation spectrum; Seasonal

and daily variationEffect of Tilt Angle.

Electricity sector in India

The electricity sector in India supplies the world's 6th largest energy consumer, accounting for 3.4% of global energy consumption by more than 17% of global population.

The Energy policy of India is predominantly controlled by the Government of India's, Ministry of Power, Ministry of Coal and Ministry of New Renewable Energy and administered locally by Public Sector Undertakings (PSUs).

Data CenterDG Set (5 kVA)

Battery Bank (60 Nos)

Power Center& Inverter

Solar Panels(Total 5 kVA)75 W/Panel45 Panels

Wind Generator(5 kVA)

WIND-SOLAR-DIESEL TRI-BRID POWER SYSTEM

64.75% from thermal power plants, 21.73% from hydroelectric power plants, 2.78% from  nuclear power plants. 

& 10.73% from Renewable Energy Sources.

More than 50% of India's commercial energy demand is met through the country's vast coal reserves. 

The country has also invested heavily in recent years in renewable energy utilization, especially  wind energy. In 2010, India's installed wind generated electric capacity was 13,064 MW. Additionally, India has committed massive amount of funds for the construction of various nuclear reactors which would generate at least 30,000 MW. 

In July 2009, India unveiled a $19 billion plan to produce 20,000 MW of solar power by 2022.

Due to the fast-paced growth of India's economy, the country's energy demand has grown an average of 3.6% per annum over the past 30 years. In December 2010, the installed power generation capacity of India stood at 165,000 MW.

The Indian government has set a modest target to add approximately 78,000 MW of installed generation capacity by 2012 .

The total demand for electricity in India is expected to cross 950,000 MW by 2030.

Total Installed Capacity (as on 28-02-2011) is 171,926.40 MW

Renewable energy in India is a sector that is still undeveloped. India was the first country in the world to set up a ministry of non-conventional energy resources, in early 1980s.

However its success has been very spotty. In recent years India has been lagging behind other nations in the use of renewable energy (RE). The share of RE in the energy sector is less than 8% of India's total energy needs. Renewable energy in India comes under the purview of the Ministry of New and Renewable Energy.

Solar power in IndiaThe first Indian solar thermal power

project (2X50MW) is in progress in Phalodi (Rajasthan), and is constructed by CORPORATE ISPAT ALLOY LTD.

The solar thermal power plant has cost 4 times as much as the coal based steam thermal power plant.

Name of PlantDC

Peak Power (MW)

Notes

Sivaganga Photovoltaic Plant 5 Completed December 2010

Kolar Photovoltaic Plant 3 Completed May 2010

Itnal Photovoltaic Plant, Belgaum 3 Completed April 2010

Azure Power - Photovoltaic Plant 2 2009

Jamuria Photovoltaic Plant 2 2009

NDPC Photovoltaic Plant 1 2010

Thyagaraj stadium Plant-Delhi 1 April, 2010

Gandhinagar Solar Plant 1 January 21, 2011

Tata - Mulshi, Maharashtra 3 Commissioned April 2011

Azure Power - Sabarkantha, Gujarat 5 Commissioned June 2011

Moser Baer - Patan, Gujarat 30 To Be Commissioned July 2011

Tata - Mayiladuthurai, Tamil Nadu 1 Commissioned July 2011

India's largest photovoltaic (PV) power plants

What is Solar Energy?Originates with the thermonuclear

fusion reactions occurring in the sun.

Represents the entire electromagnetic radiation (visible light, infrared, ultraviolet, x-rays, and radio waves).

Advantages and Disadvantages

• Advantages• All chemical and radioactive polluting

byproducts of the thermonuclear reactions remain behind on the sun, while only pure radiant energy reaches the Earth.

• Energy reaching the earth is incredible. By one calculation, 30 days of sunshine striking the Earth have the energy equivalent of the total of all the planet’s fossil fuels, both used and unused!

• Disadvantages• Sun does not shine consistently.• Solar energy is a diffuse source. To harness it,

we must concentrate it into an amount and from that we can use, such as heat and electricity.

• Addressed by approaching the problem through:

1) collection, 2) conversion, 3) storage.

Passage through the atmosphere

How much solar energy?

The surface receives about 51% of the total solar energy that reaches the Earth. Only this amount is usable.

At any given point on Earth the amount of insolation (solar energy) available to heat the surface depends on 3 factors :

1) Angle of Insolation

2) Duration of Insolation

3) Energy Absorption and Reflection by the atmosphere and Earth’s surface

These Factors Effect the intensity of Insolation: at a given point, the greater the intensity, the higher the average temperature of that location

1.)Angle of Insolation (AOI)The angle of the sun’s rays hitting the earth

Measured from the Horizon up to position of the sun -This angle is dependent on:

A.)Time of day: Noon has the greatest Angle of Ins. When the sun is most directly overhead: At 90 , ͦthe sun hits the earth perpendicularly= Vertical Rays B.)Tilt of the Earth:

Greater AOI when the sun is directly overhead (90 ͦAOI)

C.)Latitude: only between the equator and tropics it is possible for the suns rays to be vertical (directly overhead)

How the angle at which light hits the surface effects INTENSITY

2.)Duration of Insolation (DOI) = time from sunrise to sunset

Rule of thumb: Any point on earth receives the most heat when the sun is highest in the sky and when the duration is the longest (longer days) *Duration varies with seasons and Latitude.

Greatest DOI is on June 21st-The further north you go, the longer the day lasts (NY=42 N)ͦEquinoxesSun is directly overheadSpring(March 21): at 0ͦFall (Sept. 23): at 0 ͦSolsticesSummer(June 21):23 ½ ͦNWinter (Dec 21): 23 ½ S ͦ

Absorption of Insolation (solar energy)• Darker objects absorb energy faster than lighter but

lose energy faster (Easy Come, Easy Go) (Ex: Land and Sea)

• The Atm:Ozone absorbs short wave radiation (gamma, beta x-rays) H20(g) and CO2 absorb long wave radiation (infrared)

• Land and water ABSORB visible light and reradiate this solar energy back out as infrared

(long wave) TERRESTRIAL radiation

Solar Energy Potential

• As of February 2006, Photovoltaic technology accounted for less than 1% of worldwide electricity generation.

• The amount of solar energy that reaches the Earth’s surface every hour is greater than humankind’s total demand for energy in one year

SOLAR RADIATION Atmospheric Effects: Solar radiation is

absorbed, scattered and reflected by components of the atmosphere.

The amount of radiation reaching the earth is less than what entered the top of the atmosphere. We classify it in two categories:

Direct Radiation: radiation from the sun that reaches the earth without scattering.

Diffuse Radiation: radiation that is scattered by the atmosphere and clouds.

Solar Radiation

Measurement of solar radiation are important because of increasing number of solar heating and cooling applications and the need for accurate solar irradiation data to predict performance.

Two types of instruments:

1. Pyreheliometer2. Pyranometer

Solar Radiation Measurement:

SOLAR RADIATION DATA

Most of the data on solar radiation received on the surface of the earth are measured by solarimeter which give readings for instantaneous measurements at rate throughout the day total radiation on a horizontal surface.

India lies between latitude 7o and 37oN and receives an annual average intensity of solar radiation between 16700-29260 KJ/m2/day (400-700 Cal/Cm2/day).

Peak values are generally measured in April or May with parts of Rajasthan and Gujarat receiving over 25100 KJ/m2/day (600 Cal/Cm2/day).

During the monsoon and winter months the daily solar radiation decreases to about 16700 KJ/m2/day (400 Cal/Cm2/day).

The annual daily diffuse radiation received over the whole country is observed to be about 7300 KJ/m2/day .

The minimum values of diffuse radiation measured over many parts of the country during Nov & Dec are between 3135-4180 KJ/m2/day while maximum values measured over the whole country are about 12550 KJ/m2/day specially in July in Gujarat.

Estimation of Average SolarMonthly average horizontal solar radiation Hav was given by Angstrom (1924) is

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Radiation:

Location a b Location a b

Ahmadabad 0.28 0.48 Mangalore 0.27 0.43

Bangalore 0.18 0.64 Shillong 0.22 0.57

Baroda 0.28 0.48 Srinagar 0.35 0.40

Bhopal 0.27 0.50 Trivendrum 0.37 0.39

Calcutta 0.28 0.42 Vishakhapatnam 0.28 0.47

Jodhapur 0.33 0.46 New Delhi 0.25 0.57

Madras 0.30 0.44 Roorkee 0.25 0.56

Constant a and b for some Indian Towns

1.Tilt angle is the vertical angle between the horizontal and the array surface.

Array orientation is defined by two angles:

• Maximum energy gain will be achieved by orienting the array surface at a tilt angle close to the value of the local latitude –In high latitudes arrays should be very steep and vice versa.

• For optimal performance the tilt angle should be adjusted from the latitude angle by an amount equal to the average declination during that time.

• During the summer the average declination is +15º, so we should have a tilt of latitude minus 15º to make the array perpendicular to the average solar path –during the summer.

• Array Azimuth angle will be optimal when that array is due south.

• Sun trackers allow the PV array to change the tilt angle, the azimuth angle, or both –generally is not considered cannot be made cost effective.