SOLAR ENERGY

By -Kevin JosephMBA (Energy Trading)

Photo-Voltaic Cell

It is based on the photovoltaic effect.

The photovoltaic effect means the generation of a potential difference at the junction of two different materials in response to visible or other radiation.

a Photo-Voltaic with a 10cm2 surface area, a light with 10W of power falls. The maximum electric power that this cell can produce would be 3W.

Photovoltaic Solar Cells Efficiency Comparison

Monocrystalline Cells (Silicon) : 15 – 20%

Monocrystalline Cells (Gallium Arsenide) : 20 – 35%

Polycrystalline : 10% Amorphous: 7 – 10% Hybrid: 30 – 45%

Parabolic Trough Systems The sun's energy is concentrated by parabolically curved, trough-

shaped reflectors onto a receiver pipe running along the inside of the curved surface. This energy heats oil flowing through the pipe, and the heat energy is then used to generate electricity in a conventional steam generator.

A collector field comprises many troughs in parallel rows aligned on a north-south axis. This configuration enables the single-axis troughs to track the sun from east to west during the day to ensure that the sun is continuously focused on the receiver pipes. Individual trough systems currently can generate about 80 megawatts of electricity.

Range in size from 14 to 80 MW and represent

A total of 354 MW of installed around the world.

A heat transfer fluid (HTF) is used as a heat exchangers to drive a steam turbine system.

Power Tower Systems A power tower converts sunshine into clean electricity for the

world’s electricity grids. The technology utilizes many large, sun-tracking mirrors (heliostats) to focus sunlight on a receiver at the top of a tower. A heat transfer fluid heated in the receiver is used to generate steam, which, in turn, is used in a conventional turbine-generator to produce electricity.

Early power towers (such as the Solar One plant) utilized steam as the heat transfer fluid; current US designs (including Solar Two, pictured) utilize molten nitrate salt because of its superior heat transfer and energy storage capabilities. Current European designs use air as heat transfer medium because of its high temperature and its good handability

Salt Water (Brine) is heated to 565ºC

Ability to generate 10 MW

Second Generation Renewable Energy Technologies

Ocean Thermal Energy Conversion Here we use the temperature difference between the hot

surface of the ocean and the cooler, deeper layers beneath to drive a heat engine.

The average range to get a temperature gradient of about 20ºC-35ºC is as 500–1000m or 1000–3000ft.

Ammonia is used as a heat exchange fluid as it has a boiling point of -33.5ºC

A 10-MW closed cycle OTEC pilot system is operational at Hawaii. This system is being designed to expand to 100-MW commercial systems in the near future.

There are two other plaans of 2 and 7MW capacity in Hanian and Japan

Makai Ocean Engineering OTEC project

Tidal energy Tides are caused by the gravitational pull of

the moon and sun, and the rotation of the earth.

Ocean Currents are always flowing in a particular direction 24x7.

St. Lawrence River's kinetic energy and turn it into electricity. This project is for 15 megawatts,

West coast, Ontario, Canada, 15MW capacity

Advantages No fuel cost No Pollution Completely renewable Very flexible regarding location of plant

DisadvantagesEfficiency is lessNo output during Night or Cloudy

weatherPlant implementation cost very high

Cost per 1MW

Solar PV Cells – Rs.1,438/kW

Trough System – Rs.7,182/kW

Solar Tower – Rs.4,380/kW

OTEC - ?? Tidal - ??

International Project Database