Active and Passive Solar Power

The importance of solar power can be gauged from the fact that the energy that reaches from sun on earth for one hour is more than enough to satisfy the global energy demand for an entire year, if all the heat and light can be harnessed. But practically, it’s not possible. There are some technologies we have for harnessing this energy to make it usable. These include solar heating, photovoltaics, solar thermal energy, solar architecture and artificial photosynthesis.

The solar energy is highly appealing because of two reasons viz. first, large magnitude of solar energy available and second, its clean, renewable source of energy. The energy output of1 Kilo Watt solar energy is roughly equivalent to the burning of 170 pounds of coal and releasing of 300 pounds of carbon dioxide into the atmosphere”. Thus, solar energy is non-polluting, viable and renewable source of energy that can mitigate the challenge of global warming.

Active and Passive Solar Energy

The difference between active and passive solar energy is of how the solar energy is collected and harnessed. A passive solar system does not involve the mechanical devices to capture the solar energy. One example is of green houses. In green houses, the sun’s rays pass through the glass roof / windows and the interior absorbs and retains the heat. The passive solar energy collectors simply work on the basic law of thermodynamics that heat moves from warm to cool areas and surfaces. The passive collectors would pass on the heat captured from sun via convection.

In contrast, the active solar system uses external devices to collect, store and convert the solar energy. They absorb the solar energy, store it for later use and convert it to make it usable. These include photovoltaic systems, concentrated solar power and solar water heating.