The Photovoltaic Effect

(the magic that makes solar panels work)

The photovoltaic effect is the fancy name given to the phenomenon of converting light to electricity in a conventional solar panel.

Electricity is simply a flow of electrons running around a closed circuit. So how do we create a flow of electrons using a solar PV panel and sunshine?

The internal workings of solar panels are quite complex, but I’ll have a go at explaining. Don’t worry too much if you don’t understand the next paragraph!

The photons that make up light bombard the solar PV panel and dislodge electrons from their resting places. These electrons randomly flow around inside the silicon leaving holes in their place. Due to the laws of physics, the electrons then recombine. During all of this activity, energy is released and is what we capture and is called the photovoltaic effect.

If you are like me and learn by pictures, then the following diagrams illustraiting the PV effect may make more sense:

1) The atoms in the silicon crystals in the solar PV panels are surrounded by electrons:

atom in solar pv panel

2) The sunlight falls on the crystals of silicon and "electrons" are ejected and bounce around randomly:

light dislodges the electrons in the silicon crystal

3) This leaves behind an electron hole:

An electron hole is left behind

4) When an electron finds this hole and recombines, it creates energy which we can capture as electricity:

.. and that is my best effort at explaining how the solar panels on your roof take sunlight in and spit electricity out through the photovoltaic effect. How did I do? If you're interesting in learning more about modules, read my article on how solar panels work.

From the solar panels, heavy duty wires capture the electricity and feed into a box of electronics called an ‘Inverter’. The primary purpose of the solar inverter is to boost the fairly feeble flow of electricity (known as ‘low voltage DC’) into nice, clean and reliable, high voltage 240V AC electricity that is compatible with both your household appliances and the electricity grid.

Any of the electricity transmitted by the inverter that is not used by your house and gadgets will, by the natural forces of physics, flow through your meter and out into the wider world via the mains electricity grid.

>>Next: How a solar system works >>

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