SEMINAR PRESENTED BY P.K BARAD

1. What is Solar Energy?
Solar energy refers to energy from the sun. The sun has produced energy for billions of
years. It is the most important source of energy for life forms. It is a renewable source of
energy unlike non- renewable sources such as fossil fuels. Solar energy technologies
use the sun’s energy to light homes, produce hot water, heat homes and electricity.
Uses of Solar Energy
The main benefit of solar energy is that it does not produce any pollutants and is
one of the cleanest source of energy. It is a renewable source of energy, requires low
maintenance and are easy to install. The only limitation that solar energy possess is that
it cannot be used at night and amount of sunlight that is received on earth is depends on
location, time of day, time of year, and weather conditions.
Solar energy is a completely free source of energy and it is found in abundance. Though
the sun is 90 million miles from the earth, it takes less than 10 minutes for light to travel
from that much of distance.
Solar energy which comprises of radiant heat and light from the sun can be
harnessed with some modern technology like photo-voltaic, solar heating, artificial
photosynthesis, solar architecture and solar thermal electricity.
The solar technology can be distinguished into active and passive. Photovoltaic
panels and solar thermal collectors which harness solar energy are examples of active
solar technology. Passive technology includes constructing rooms to improve air
circulation, orienting space to favorably use sunlight.
The earth gets 174 Petawatts of incoming solar radiation in the upper atmosphere.
About 30% is reflected back to space and the rest is absorbed by oceans, clouds and
land masses.
The water cycle is an important result of solar insulation. The earth, oceans and
atmosphere absorb solar radiation and their temperature rises. Warm air rises from the
oceans causing convection. When this air rises to high altitudes, clouds are created by
condensation of water vapor. These clouds cause rains that bring water back to the
earth’s surface which completes the water cycle.
Solar energy has also another use. By means of photosynthesis, solar energy is
converted by green plants into chemical energy which creates the bio mass that makes
up the fossil fuels.
Horticulture and agriculture seek to make the maximum use of solar energy.
These include techniques like timing of planting cycles and mixing of plant varieties.
Green houses are also used to convert light into heat to promote year round cultivation of
special crops.

2. Solar powered hot water systems utilize solar energy to heat water. In certain
areas, 60 to 70% of water used domestically for temperatures as high as 60 degree
Celsius can be made available by solar heating.
Solar chimneys are passive solar ventilation systems. Shafts connect the interior
and exterior of the building. The functioning can be improved by glazing and using
thermal mass materials.
Solar energy can also be used for making potable, brackish or saline water.
Without using electricity or chemicals, waste water can be treated. Creating salt from sea
water is also one of the oldest uses of solar energy.
Clothes can be dried in the sun using clothes lines, cloth racks etc. Food can be cooked,
dried or pasteurized using solar energy.
Solar power is the most exciting use of solar energy. It is how solar energy is
converted into electricity by using either photo-voltaic (direct method) or concentrated
solar power (Indirect). Large beams of sunlight are focused into a small beam using
mirrors or lenses in the case of concentrated solar power. Photoelectric effect is used by
Photo voltaic to convert solar energy into electric energy.
Solar chemical processes replace fossil fuels as a source for chemical energy and
can make solar energy storable and transportable. Photosynthesis can create a variety of
fuels. Technology for producing Hydrogen is a major area of solar chemical research.
Thermal storage systems can store solar energy in the form of heat by using
common materials with high specific heat such as stone, earth and water. Solar energy
can be stored also in molten salts.
Solar energy is being recognized as the future of alternative energy sources as it is non
polluting and helps combat the Greenhouse effect on global climate created by use of
fossils fuels.
Common domestic use of solar energy is from solar panels which absorb solar
energy to use for cooking and heating water.Solar energy produce no pollution, have no
environmental effects and is ecologically acceptable.
Solar energy is one of the most widely used renewable source of energy. One can use
renewable energy technologies to convert solar energy into electricity.
olar power is noise pollution free. It has no moving parts, and does not require any
additional fuel, other than sunlight, to produce power.
A home solar panel system consists of several solar panels, an inverter, a battery, a
charge regulator, wiring, and support materials. Sunlight is absorbed by the solar panels
and is converted to electricity by the installed system. The battery stores electricity that
can be used at a later time, like cloudy days or during the evening.
Solar energy is used in many applications including Electricity, Evaporation, Biomass,
Heating water and buildings and even for transport.

3. Potential of Solar Energy
The Earth receives 174,000 terawatts (TW) of incoming solar radiation (insolation)
at the upper atmosphere.[5] Approximately 30% is reflected back to space while the rest
is absorbed by clouds, oceans and land masses. The spectrum of solar light at the
Earth's surface is mostly spread across the visible and near-infrared ranges with a small
part in the near-ultraviolet.[6] Most of the world's population live in areas with insolation
levels of 150-300 watts/m², or 3.5-7.0 kWh/m² per day.
Solar radiation is absorbed by the Earth's land surface, oceans – which cover
about 71% of the globe – and atmosphere. Warm air containing evaporated water from
the oceans rises, causing atmospheric circulation or convection. When the air reaches a
high altitude, where the temperature is low, water vapor condenses into clouds, which
rain onto the Earth's surface, completing the water cycle. The latent heat of water
condensation amplifies convection, producing atmospheric phenomena such as
wind, cyclones and anti-cyclones.[7] Sunlight absorbed by the oceans and land masses
keeps the surface at an average temperature of 14 °C.[8]By photosynthesis, green plants
convert solar energy into chemically stored energy, which produces food, wood and
the biomass from which fossil fuels are derived.[9]
The total solar energy absorbed by Earth's atmosphere, oceans and land masses
is approximately 3,850,000 exajoules (EJ) per year.[10] In 2002, this was more energy in
one hour than the world used in one year.[11][12] Photosynthesis captures approximately
3,000 EJ per year in biomass.[13] The amount of solar energy reaching the surface of the
planet is so vast that in one year it is about twice as much as will ever be obtained from
all of the Earth's non-renewable resources of coal, oil, natural gas, and mined uranium
combined,[14]
The potential solar energy that could be used by humans differs from the amount
of solar energy present near the surface of the planet because factors such as
geography, time variation, cloud cover, and the land available to humans limit the amount
of solar energy that we can acquire.
Geography affects solar energy potential because areas that are closer to
the equator have a greater amount of solar radiation. However, the use
of photovoltaics that can follow the position of the sun can significantly increase the solar
energy potential in areas that are farther from the equator.[4] Time variation effects the
potential of solar energy because during the nighttime there is little solar radiation on the
surface of the Earth for solar panels to absorb. This limits the amount of energy that solar
panels can absorb in one day. Cloud cover can affect the potential of solar panels
because clouds block incoming light from the sun and reduce the light available for solar
cells.
Heating
Thermal mass is any material that can be used to store heat—heat from the Sun
in the case of solar energy. Common thermal mass materials include stone, cement and
water. Historically they have been used in arid climates or warm temperate regions to

4. keep buildings cool by absorbing solar energy during the day and radiating stored heat to
the cooler atmosphere at night. However, they can be used in cold temperate areas to
maintain warmth as well. The size and placement of thermal mass depend on several
factors such as climate, daylighting and shading conditions. When properly incorporated,
thermal mass maintains space temperatures in a comfortable range and reduces the
need for auxiliary heating and cooling equipment.
A solar chimney (or thermal chimney, in this context) is a passive solar ventilation
system composed of a vertical shaft connecting the interior and exterior of a building. As
the chimney warms, the air inside is heated causing an updraft that pulls air through the
building. Performance can be improved by using glazing and thermal mass materials in a
way that mimics greenhouses.
Cooking
Solar cookers use sunlight for cooking, drying and pasteurization
Electricity production
Solar power is the conversion of sunlight into electricity, either directly
using photovoltaics (PV), or indirectly using concentrated solar power (CSP). CSP
systems use lenses or mirrors and tracking systems to focus a large area of sunlight into
a small beam. PV converts light into electric current using the photoelectric effect.
Agriculture and horticulture
Agriculture and horticulture seek to optimize the capture of solar energy in order to
optimize the productivity of plants. Techniques such as timed planting cycles, tailored
row orientation, staggered heights between rows and the mixing of plant varieties can
improve crop yields.[71][72] While sunlight is generally considered a plentiful resource, the
exceptions highlight the importance of solar energy to agriculture.
Transport
Development of a solar-powered car has been an engineering goal since the
1980s. The World Solar Challenge is a biannual solar-powered car race,
Fuel production
Solar chemical processes use solar energy to drive chemical reactions. These
processes offset energy that would otherwise come from a fossil fuel source and can
also convert solar energy into storable and transportable fuels.
Emerging Technology
Concentrator photovoltaics (CPV) systems employ sunlight concentrated onto
photovoltaic surfaces for the purpose of electrical power production. Contrary to
conventional photovoltaic systems, it uses lenses and curved mirrors to focus sunlight
onto small, but highly efficient, multi-junction solar cells. Solar concentrators of all

5. varieties may be used, and these are often mounted on a solar tracker in order to keep
the focal point upon the cell as the sun moves across the sky.[95] Luminescent solar
concentrators (when combined with a PV-solar cell) can also be regarded as a CPV
system. Concentrated photovoltaics are useful as they can improve efficiency of PV-solar
panels drastically. In addition, most solar panels on spacecraft are also made of high
efficient multi-junction photovoltaic cells to derive electricity from sunlight when operating
in the inner Solar System.
SOLAR LIGHTING
Solar Lighting is another application of solar photovoltaic. Solar Lighting has many
types. The solar lighting can be solar street lighting,solar flood lighting, solar garden
lighting or some special applications of lighting. In solar lighting, very important thing is
the designing of solution so that the lights work automatically and remain on as per
requirement. Most of the solar lights, we see un-lit in the nights or they lit for some hours
and then go off against the timing requirement. The reason for this is that the un-
professional people have designed and sold under-designed and low quality systems.
While purchasing the solar lighting systems, define your specifications and then buy
systems accordingly and monitor their operational hours continuously.
SOLAR ELECTRIC POWER GENERATION
Solar Electric Power can be generated varying from 100 Watts small solar home systems
to 100 MW Solar Power Plants or sometimes more than that. The solar power systems
are of two types; one is off-grid and other is on-grid systems. In off-grid systems, the
system has no link with Utility grid and components used in Systems are Solar Panels,
Charge Controllers, Inverters, Deep Cycle Batteries, mounting and electric accessories.
Solar Panels convert solar radiations into electric current and this current passes through
charge controllers which charges the battery by controlling current for the battery. Charge
controllers maintain control on charging the battery for its long life. So the DC power is
stored in Batteries and this stored energy is converted into AC Power to operate the AC
appliances. The DC appliances can be operated directly with the battery. So DC and AC
load can be operated through a solar power system.
SOLAR THERMAL APPLICATIONS
Solar water heating is one application of the Solar Thermal. Solar Water Heaters
(SWH) are of two types; one is non-pressurized solar water heating (SWH) and other is
Pressurized Solar Water Heating. In non-pressurized solar water heater, the collector
(Vacuum tubes or flat plate) and tank are mounted on one fixture and are in one
integrated unit. Tank is mounted at top of the collector. There is no pump used in this
type of system.
This system works on flow of water through gravity from overhead tank to solar
water heater tank (stainless steel tank with 55 mm poly-urethane insulation) and from this

6. tank onward to vacuum tubes and by natural convention process, the hot water circulates
and heats up the whole tank. It usually takes four hours to heat up the water of 300 litters
up to 45 Degree in peak winter season and 60 Degree in moderate season and 90
degree in peak hot season. So the temperature of water varies as per ambient
temperature. Usually 50 Litters per person per day is taken while designing the system
for domestic use. For industrial application of washing and cleaning, the total water load
in terms of flow is calculated to design the system. The total number of solar water
heaters connected in parallel or series depends upon the daily water consumption and
temperature requirement.
Economics
Adjusting for inflation, it cost $96 per watt for a solar module in the mid-1970s. Process
improvements and a very large boost in production have brought that figure down to 68
cents per watt in February 2016, according to data from Bloomberg New Energy
Finance. Palo Alto California signed a wholesale purchase agreement in 2016 that
secured solar power for 3.7 cents per kilowatt-hour. And in sunny Dubai large-scale solar
generated electricity sold in 2016 for just 2.99 cents per kilowatt-hour -- "competitive with
any form of fossil-based electricity and cheaper than most.
Photovoltaic systems use no fuel, and modules typically last 25 to 40 years. Thus, capital
costs make up most of the cost of solar power. Operations and maintenance costs for
new utility-scale solar plants in the US are estimated to be 9 percent of the cost of
photovoltaic electricity, and 17 percent of the cost of solar thermal
electricity.Governments have created various financial incentives to encourage the use of
solar power
Environmental impacts
Unlike fossil fuel based technologies, solar power does not lead to any harmful emissions
during operation, but the production of the panels leads to some amount of pollution.
Greenhouse gases
The Life-cycle greenhouse-gas emissions of solar power are in the range of 22 to
46 gram (g) per kilowatt-hour (kWh) depending on if solar thermal or solar PV is being
analyzed, respectively. With this potentially being decreased to 15 g/kWh in the
future.[76] For comparison (of weighted averages), a combined cycle gas-fired power
plant emits some 400–599 g/kWh,[77] an oil-fired power plant 893 g/kWh,[77] a coal-fired

7. power plant 915–994 g/kWh[78] or with carbon capture and storage some 200 g/kWh, and
a geothermal high-temp. power plant 91–122 g/kWh.
The life cycle emission intensity of hydro, wind and nuclear power are lower than
solar's as of 2011 as published by the IPCC, and discussed in the article Life-cycle
greenhouse-gas emissions of energy sources. Similar to all energy sources were their
total life cycle emissions primarily lay in the construction and transportation phase, the
switch to low carbon power in the manufacturing and transportation of solar devices
would further reduce carbon emissions. BP Solar owns two factories built by Solarex
(one in Maryland, the other in Virginia) in which all of the energy used to manufacture
solar panels is produced by solar panels. A 1-kilowatt system eliminates the burning of
approximately 170 pounds of coal, 300 pounds of carbon dioxide from being released
into the atmosphere, and saves up to 105 gallons of water consumption monthly.[79]
The US National Renewable Energy Laboratory (NREL), in harmonizing the
disparate estimates of life-cycle GHG emissions for solar PV, found that the most critical
parameter was the solar insolation of the site: GHG emissions factors for PV solar are
inversely proportional to insolation.[80] For a site with insolation of 1700 kWh/m2/year,
typical of southern Europe, NREL researchers estimated GHG emissions of
45 gCO2e/kWh. Using the same assumptions, at Phoenix, USA, with insolation of
2400 kWh/m2/year, the GHG emissions factor would be reduced to 32 g of CO2e/kWh.[81]
The New Zealand Parliamentary Commissioner for the Environment found that the
solar PV would have little impact on the country's greenhouse gas emissions. The
country already generates 80 percent of its electricity from renewable resources
(primarily hydroelectricity and geothermal) and national electricity usage peaks on winter
evenings whereas solar generation peaks on summer afternoons, meaning a large
uptake of solar PV would end up displacing other renewable generators before fossil-
fueled power plants