The Many Applications of Solar Energy

The amount of solar energy that falls on the earth’s surface in 40 minutes equals the total annual energy consumption of all the world’s people… Put differently, 27 years’ worth of worldwide energy consumption equals only one day’s worth of solar energy hitting the earth (1).

Solar power can be harnessed for many purposes, from warming our homes, to providing us with hot water, to powering electric light, to cooking our meals.

Perhaps because of its many applications, solar technology is widely used and is the largest renewable source of energy the world.

The sun’s power is especially valued in developing countries.

India recently unveiled a plan to invest $19 billion to produce 20 GW of solar power by 2020, requiring solar power in all government buildings as well as in hospitals and hotels.

Solar energy may be harnessed for purposes that may be considered active or passive. Passive building and solar techniques include solar chimneys, trombe walls for thermal mass dispersion and natural lighting (aka daylighting).

Active applications for solar technology include electricity generation, water pumping and water heating. The photo below shows a solar panel that powers a water pump.

Solar Electric Power

Photovoltaic cells, or “solar panels”, harness the sun’s rays and convert them into electricity that may be used for almost any electrical application.
More and more it seems PV systems are custom designed to suit local weather conditions. In more advanced designs, PV can be used to provide power without the sun by integrated inverter and battery storage systems for value on cloudy and rainy days.
Some communities and buildings run completely on electricity produced by photovoltaic (PV) panels.

The many advantages of solar photovoltaics include:

• Renewable: Solar energy is a resource that is not only sustainable for energy consumption, but is definitely renewable.
• Low Maintenance: Solar panels require very little maintenance. After installation and optimization they are very reliable and they actively create electricity and do not require any type of mechanical parts in case of failure. Solar PV systems typically last between 25-30 years with minimal degradation in terms of output and production.
• No Noise: Solar panels are silent producer of electricity with no moving parts to wear out or fail.
• Zero Pollution: Solar energy does not cause pollution and does not produce any harsh residual effects.

Disadvantages of solar photovoltaics include:

• High Cost: The initial cost of purchasing and installing solar panels is often very high for full and efficient use of solar energy. Although the cost of conventional solar energy technologies, such as silicon flat panels, are always dropping, and new technologies are being developed, the high cost of solar is the primary reason many countries subsidize solar energy projects.
• Location and size: The orientation, location and size of solar panels is of major importance in the generation of electricity. Regions which remain mostly cloudy and foggy, such as Seattle, will produce electricity but at a reduced rate and may require more panels to generate enough electricity, or the use of battery backup systems as mentioned above. For residential users, a solar energy installation may not require huge space but for large commercial arrays, a large area is required for the system to be productive in providing a meaningful source of electricity.
• Inefficiency: Since not all the energy from the sun is absorbed by the solar panels therefore most solar panels have a 20% efficiency rate which means 80% of the sun’s energy is wasted and is not harnessed. New emerging technologies, such as perovskite, however have increased the rate of efficiency of solar panels from 20 to 25-30% and on the downside have increased the cost of solar panels as well.

Solar Lamps

Solar lamps, aka “Solar lanterns” actively provide light as an alternative to kerosene lamps. These lanterns are typically an electric, battery powered high efficiency lamp (such as a LED or high efficiency CFL) attached to an inverter and a small solar array.

In India there are over 5,000,000 solar powered lanterns and solar powered home lights, which are in need in rural India due to the country’s under-developed grid system. Over 80,000 villages in India are currently without electrical power through the conventional grid.

Solar Kitchens

Also known as “solar cookers” or “solar ovens”, solar kitchens use a solar bowl that is incorporated to harness solar energy for cooking.

The sun's rays are trapped by a hemispherical mirror and focused on a boiler which follows the sun's position. The focused boilers can range in size from small and portable to enormous. For instance, the largest commercial kitchen in India is a collaboration between the Academy for a Better World and Brahma Kumaris World Spiritual University, with technology from Solare-Brücke, Germany.

In some cases, the cylindrical boiler is automated to turn with the angle of the sun by means of software/a computerized tracking device.

The solar system component in a solar bowl design, uses hundreds of mirrors to focus sunlight onto the heat receiver. The coils around the heat receiver are filled with water and when the water turns to steam, it is pumped into necessary locations.
Some examples of solar cookers include:

• http://gosunstove.com/collections/solar-ovens
• http://www.sunoven.com/

Passive Solar Heating

The use of solar passive architecture can provide increased comfort in buildings, while reducing the use of conventional fuels and electricity. The benefits of active solar energy are amplified in energy efficient buildings, such as passive houses and Net Zero buildings.

In the mid seventies a residential building was constructed called 'Eco-house'. Eco-House was one of the very first attempts in India to build a climatically appropriate house which integrated solar cooking and water heating with rooftop rainfall harvesting and a multi feed biogas plant.

A roof mounted wind generator was also contemplated but not installed.

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(1) http://www.txses.org/solar/content/solar-energy-facts-you-should-know