Renewable energy comes from natural resources like wind, hydropower, solar, biomass and geothermal that replenish naturally. Solar power converts sunlight into electricity or heat using photovoltaics or solar thermal. A flat-plate solar collector consists of an absorber plate and glass covering that heats a liquid as sunlight is absorbed. Photovoltaic cells directly convert sunlight into electricity through the photovoltaic effect in semiconducting materials like silicon. Solar energy has advantages of being renewable, pollution-free and available for decentralized use, but is intermittent and dependent on weather conditions.

1. Renewable energy
 Renewable energy is energy which comes from natural
resources , which are renewable (naturally replenished).
Wind power
Hydropower
Solar energy
Biomass
Biofuel
Geothermal energy
 About 16% of global final energy consumption comes from
renewables
 New renewables (small hydro, modern biomass, wind,
geothermal, and biofuels) accounted for another 3%

2. Solar Energy
 "Solar power" is defined as the conversion of solar
energy (light) to a form of useable energy such as
electricity or heat.
 Solar powered electrical generation relies on
photovoltaic's and solar thermal power

3. Flat-plate collector

4. Flat-plate collectors
 A typical flat-plate collector is a metal box with a
glass or plastic cover (called glazing) on top and a
dark-colored absorber plate on the bottom.
 5 important components are
 A Transparent front cover/Glazing
 Absorber plate
 Tubes, fins, passages or channels
 Insulation
 Casing/ Collector housing

5. Working of flat plate Collector
 Absorber most important part and works on the
principle of black body
 Sunlight passes through the glazing and
strikes the absorber plate, which heats up,
changing solar energy into heat energy.
 The heat is transferred to liquid passing
through pipes attached to the absorber
plate.
 Absorber plates are usually made of metal,
typically copper, aluminum or steel, Copper is
better.

6. Working of flat plate Collector
 The collector housing can be made of plastic,
metal or wood
 Glass front cover must be sealed
 Heat does not escape
 Dirt, insects or humidity do not get into the collector
itself.
 Sides and bottom of the collector are highly
insulated to minimize heat loss
 Prevent most of the convection losses.
 Reduces heat radiation from the absorber into the
environment

7. Photovoltaics
 A solar cell (also called a photovoltaic cell) is an
electrical device that converts the energy of light
directly into electricity by the photovoltaic
effect.
 Photoelectric cell , when exposed to light, can
generate and support an electric current without
being attached to any external voltage source.
 Photo-voltaics can literally be translated to
"light-electricity."

8. Working of photovoltaic cell

9. Working of photovoltaic cell
 The solar cell works in three steps:
 Photons in sunlight hit the solar panel and are absorbed by
semiconducting materials, such as silicon.
 Electrons (negatively charged) are knocked out of their normal
energy state, causing an electric potential difference.
 Current starts flowing through the material to cancel the
potential and this electricity is captured.
 Due to the special composition of solar cells, the electrons
are only allowed to move in a single direction.
 An array of solar cells converts solar energy into a usable amount
of direct current (DC) electricity.

10. Advantages of Solar energy
 Renewable and clean source of energy
 Free from pollution/noise
 Cost free
 Reliable, Can be used in remote areas
 No contribution to climate change.
 Decentralized system- locals as per their needs
 Flexibility of applications, from small scale to big
scale

11. Disadvantages
 Solar energy is not available at night
 Mostly Diffused/ Scattered
 Non continuous/ Intermittent
 Seasonal / Daily fluctuations
 Cloudy days
 Time consuming