Renewable energyRenewable energy is energy which comes from natural

resources , which are renewable (naturally replenished). Wind powerHydropowerSolar energyBiomassBiofuelGeothermal 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%

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

Flat-plate collector

Flat-plate collectorsA 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 areA Transparent front cover/GlazingAbsorber plateTubes, fins, passages or channelsInsulationCasing/ Collector housing

Working of flat plate CollectorAbsorber most important part and works on

the principle of black bodySunlight 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.

Working of flat plate CollectorThe collector housing can be made of plastic,

metal or wood Glass front cover must be sealed

Heat does not escapeDirt, insects or humidity do not get into the

collector itself. Sides and bottom of the collector are highly

insulated to minimize heat lossPrevent most of the convection losses.Reduces heat radiation from the absorber into the

environment

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."

Working of photovoltaic cell

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.

Advantages of Solar energyRenewable and clean source of energyFree from pollution/noiseCost freeReliable, Can be used in remote areas No contribution to climate change. Decentralized system- locals as per their needsFlexibility of applications, from small scale

to big scale

DisadvantagesSolar energy is not available at night Mostly Diffused/ ScatteredNon continuous/ IntermittentSeasonal / Daily fluctuationsCloudy days Time consuming