Hesperian Health Guides

Hesperian Health Guides

Solar Power

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HealthWiki > A Community Guide to Environmental Health > Chapter 23: Clean Energy > Solar Power



Solar panels on the roof of a house collect energy from the sun.

When you feel the sun heating your body or the air in your house, this is solar energy. There are many ways to make efficient use of the sun’s energy to heat water, to make water safe, and to cook food or heat a house. The sun’s energy can also be used to make electricity.

Solar energy requires the use of solar panels or solar cells to capture the sunlight and change it into electricity. Because the sun is not always shining, the electricity made must be stored in batteries before being used to run lights, motors, and other machines.

A solar energy system can be costly to install because it requires solar panels, batteries, and other parts. But sunlight is free (and endlessly renewable). Once a solar system is in place, it costs little to run and maintain. The biggest costs of maintaining a solar system are replacing the batteries every 3 to 5 years and replacing solar panels if they break.

The parts of a solar electric system

solar panels
charge controller
fluorescent lights
switches
socket
batteries
earthing rod
invertor



(To learn more about solar energy and to contact organizations that install solar electric systems, see Other Environmental Health Resources.)

Solar hot water

In areas with a lot of sunlight, one of the most direct uses for solar energy is to heat water for drinking or bathing. Solar hot water does not require solar panels or costly equipment. All that is needed is a water storage tank, and pipe painted black to absorb the sun’s rays.

In mild climates, solar collectors are needed to heat water. They are more costly than simple solar water heaters, but less costly than the solar panels needed for electricity, and less costly than heating water with nonrenewable resources.

A simple water heater
Glass or clear plastic cover helps store heat in the water
Outlet pipe
Black absorbs heat, so a large barrel painted dull black inside and out will capture heat from the sun.
Inlet pipe


Solar water heater placed in the sun on a roof or at ground level



Water storage tank
Pipe to house or outside shower
Metal or plastic pipe painted black
Pipe where water enters
Reflective surface (sheet metal, tin foil, etc.)



Microcredit helps fund solar power


Men and women work together to build a solar power system.

Most homes in rural Sri Lanka are not connected to the national electric power system. But as in many tropical countries, the island of Sri Lanka has a lot of sunshine. In 1991, an organization called SELF (Solar Electric Light Fund) came to Sri Lanka to help people use their sunshine to make electricity.


Because they could not give away solar power systems for free, SELF came up with a way to help people pay for their own systems. Together with a Sri Lankan non-profit organization, they formed a “solar cooperative.” The cooperative set up a microcredit fund. Cooperative members paid a small down payment to have a solar system set up, and made small payments to the fund every month for up to 8 years. As the fund grew, more families were able to use it to pay for their own solar systems. After 5 years, the first 48 families had repaid enough into the microcredit fund to allow 25 more families to buy solar systems.


Building on this success, SELF began working with Sarvodaya, the largest NGO in Sri Lanka, with over 3 million members. SELF and Sarvodaya developed a “Solar Seed” program, which introduced solar electricity to over 100 villages. The program installed demonstration solar systems in community centers, schools, and Buddhist temples. SELF then organized a microcredit fund to help Sarvodaya members buy home solar systems. The program started with 300 households. A few years later, it was so successful that Sarvodaya began planning for a “million-home” solar program.


Thousands of homes in rural Sri Lanka now have solar electricity. Using the microcredit system, thousands more will soon have solar electricity. If they continue working this way, Sri Lanka may one day be the world’s first nation to run entirely on sunlight.


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