How Solar Energy Works?

The Sun is the source of life on our planet. It’s not only the source of light, but also the source of heat and other forms of energy. Even the energy stored in our food, fossil-fuel; all these are actually results of previous “insolation” (sunshine). Probably that’s why old civilizations used to worship the sun as a god. It’s amazing to know that one hour of solar energy, if fully harnessed, can fulfil a whole year of energy need on earth!

How Does Solar Energy Work?

The sunlight reaches the earth’s surface in form of:

1. light or the visible radiation (frequencies that produce the spectra “violet to red” while passing through a prism)
2. heat or invisible infrared radiation (frequencies below [=infra] red spectrum)
3. high-frequency ultra-violet radiation (frequencies beyond [=ultra] violet spectrum). The use of the light needs no elaboration. The heat is the energy we use to dry clothes, run the water-cycle (evaporation-cloud-rain). The UV is that causes the tan on our skin or causes skin-cancer.

But the light form is used in another way now-a-days, a way that has opened towards the new horizon of renewable energy; the solar-electricity. This process of converting the light into electricity is called PV or photovoltaic.

How Do Solar Cells Work

Solar Cells convert light directly into electricity. On a sunny day, the electricity converted from an area of 1 square-meter can feed a 100W light-bulb. Solar cells, or photovoltaic cells are generally silicon-based (silicon is an element extracted from sand) pieces that absorb the sunlight.

One end of the Silicon (Si) piece is doped with Boron (B) which is considered as the positive (+ve) end and the other end is doped with Phosphorus (P), which is the negative (-ve) end. When light falls onto the solar cell, electrons are displaced from the atoms of Silicon. However, the electrons tend to move towards Phosphorus which attracts electrons (negative charges). Thereby, there is a surplus of electrons in –ve end and a shortage of electrons in the +ve end.

If a conducting line is formed up outside the cell between the +ve and –ve ends, an electrical flow is generated and a working circuit is constructed. This electricity is a direct current or DC (unidirectional flow) like a battery. But DC is not suitable for common use, so DC is converted through an “inverter” to alternating current or AC. This AC can be transformed into required “voltage” through a “transformer”.

(Ref: http://science.nasa.gov/headlines/y2002/solarcells.htm).

This process of converting sunlight into electricity is called the photovoltaic process. A combination of PV cells makes a PV module, a set of PV modules form a PV panel or commonly called solar panel. Even greater powers can be achieved through a collection of PV panels put together in an “Array”.

The Chain of Harnessing Solar Energy

Summarising all these, here is the chain of Solar Energy:

a. The Sun radiates light
b. The PV cells convert solar radiation into electricity
d. This electricity is like battery-generated electricity (unidirectional flow of current) or the DC.
e. The inverter converts direct current (DC) into alternating current (AC).
f. The transformer guarantees that the voltage of the electricity coming from the inverter is the one we require.
g. The distribution scheme receives electricity produced by the system and combines it with other electric sources.
h. There could be electric meters to measure the amount of electricity produced.