Difference between Passive and Active Solar energy

With fossil fuel causing so many problems to the environment and to our health, many are turning to the sun as an alternative source of energy, just as ancient civilizations always did, thousands of years ago.


Passive vs Active Solar Energy
A house built on passive solar design

Passive solar energy does not require electronic or mechanical devices for solar radiation to be harnessed and distributed. Here, a building is designed in such a way that its walls, windows, and floors are systematically utilized to absorb solar energy, keep it, and then distribute it to heat homes and businesses. The system in place is also expected to deflect solar heat when needed and affect the movement of air for ventilation, or heat water with the least dependence on other sources of energy. Good examples of passive solar designs include solariums, sunrooms, and greenhouses.

There are also passive systems that require the use of conventional energy sources to control shutters, dampers, night insulation, and other equipment that help improve the collection, storage and usage of solar radiation. The solar forge and solar furnace were earlier, more complex passive solar energy systems but were not cost-effective to use. Water and space and heating have been found to be economically sound applications of passive solar energy.

active solar energy
A solar panel (photovoltaic) cell array

Harnessing and distribution active solar energy, on the other hand, requires the use of mechanical equipment powered by auxiliary energy. The use of solar panels is by far the most popular system for harvesting solar energy. It consists of an interconnected array of solar cells that gather the sun’s rays to generate and provide energy for commercial and residential use.

Active solar systems use pumps and electronic sensors, or controllers that work automatically to ensure energy gathering and distribution is maximized. Controllers can also help to make sure available energy is distributed in the most efficient manner. Solar trackers installed in active solar arrays are sometimes fitted with built-in sensors and motors to help track the sun’s movement across the sky.

The downside to active solar systems is that they require maintenance. They can also break down should external power sources fail.

Passive vs Active Solar Energy

So, what is the difference between passive and active solar energy?

Passive solar energy does not require mechanical equipment and electronic devices to gather and distribute solar energy. It also does not need power coming from an external, conventional source.

Active solar systems rely on pumps, sophisticated electronic devices, and motors to effectively collect and systematically provide solar energy. For these motors and electronic equipment to run, active solar systems need to be hooked up to an external power source.

Since passive solar systems do not usually depend on an external power source to operate, they rely on their heat-absorbing properties, particularly the materials used in the system. Sensors and motors running on conventional energy make active energy systems work, also maximizing their operability and effectiveness in harnessing the power of the sun.

Comparison chart

Passive solar energy Active solar energy
Does not require mechanical or electronic equipment to be harnessed Relies on pumps, motors, and electronic devices to be harnessed
Requires little or almost no maintenance Requires a lot of maintenance
Needs no external power source to operate Needs conventional power source to work
Less control in gathering and distribution of energy Allows controlled and efficient gathering and distribution of energy