In 1839, 19-year old French physicist Alexandre Edmond Becquerel discovered that certain materials would produce small amounts of electric current when exposed to light. This basic physical process of using light to generate an electric current is known as the photovoltaic effect.
However, it would be more than 100 years before engineers would develop a photovoltaic cell capable of converting enough solar energy into electricity to run electrical equipment.
The breakthrough came in 1954 when physicists at Bell Labs discovered that a Silicon semiconductor was able to convert light into electricity with 4-6% efficiency. Compared to earlier materials which were less than 1% efficient, this was a major accomplishment.
Semiconductors are the key to PV solar power. To understand why, let's take a look at the characteristics of solid matter.
There are three types of solid matter...
To generate solar electricity, semiconductors are needed. However, just shining light on a semiconductor will not create electricity. Yes, the electrons in the semiconductor will be released, but in order to generate electricity, they need to flow. To get the electrons flowing, two more pieces are needed to complete this puzzle.
First, you need to have a circuit. A circuit is simply a path for electrons to move on. The circuit creates a continuous loop which includes our semiconductor. The circuit will be made with a conductor such as copper wire.
Finally, you also need to have a positively charged semiconductor (P-type) and a negatively charged semiconductor (N-type). P-type and N-type semiconductors are created using a process known as doping. This process simply mixes another chemical element with the semiconductor to give it either a positive or a negative charge. With Silicon semiconductors, Boron is typically mixed in to create the P-type and Phosphorous the N-type.
Now we have all the pieces to the photovoltaic solar energy puzzle, so let's put them together!
A solar cell is made by joining a P-type semiconductor and an N-type semiconductor. The P-type will make up the bottom layer of the solar cell and the N-type will make up the top layer. The two layers form an electric field between them which only allows electrons to flow from the P-type semiconductor to the N-type semiconductor. This electric field provides our electric voltage.
To generate the electricity, we simply need to create a circuit that goes from the N-type to the P-type. Now when the solar cell is exposed to light, electricity will flow from the N-type layer through the circuit to the P-type layer. This is our electric current.
Now that we have both voltage and current in our solar cell, we now have pv solar power! Power is the product of voltage and current and is measured in Watts. Now, if a load is placed on the circuit, it can use the electricity generated by the pv solar energy.
For more information on solar cells, take a look at our solar cell page. From there, you can go to our solar electricity page which will explain about the different types of photovoltaic solar power systems you can use in your home.