Solar Power Cells

Calculators that run on solar power aren’t new. But before solar cells were used in consumer devices like calculators, they were used in space. Today, more and more uses are being developed for solar power cells and how they work is intriguing.

Photovoltaic cells are made from a semiconductor, often silicon, which gathers energy from the sun.  When the light hits the semiconductor, electrons break loose and are pushed in the same direction forming an electric current.   To harness this electricity, photovoltaic cells are connected to a circuit which begins at the top, sends energy through the appliance, and back toward the contacts at the bottom of the cell.

Very little movement of electrons is possible when silicon is in its natural crystalline state, so the silicon is actually impure.  Individual silicon atoms each possess four locations to which electrons can be bonded and so are relatively unstable.  But each atom typically joins to others through the sharing of electrons in their outer valances.

Silicon is not as conductive in its original form, so to get the most energy from the solar power cells, N-type silicon is used.  It is created from a reaction combining silicon with phosphorus.  The result, a free electron is available for each phosphorus atom joining with the 5 outer ring silicon electrons.

Doping silicon with boron results in P-type silicon.  The outer shell of the boron atoms have only three electrons, leaving a “hole”, which is a place into which  an electron can move.  In photovoltaic cells, one combines P-type silicon with N-type silicon.

Two different types to silicon need to be set up side by side.  The first thing that will happen is the holes and electrons begin to fill in at the shared border.  You will know when equilibrium is reached once the electrons can’t interact in that way anymore.  The two halves will separate, creating an electric field.  At that time, it will be easy for the electrons to flow from the positive side to the negative side.  However, the electrons that are already in the negative can’t flow back to the positive side.  You’ve created a one-way flow of electrons.

Photons consist of energy units from the sun, and they make energy by making contact with the atoms of the solar cell and freeing holes and electrons.  This continues the movement of electrons between holes and establishes current.  Voltage results from the field created at the site of the P-type and N-type silicon junction.

Harnessing the energy from the sun through photovoltaic solar power cells is still essentially in its infancy.  Both commercial and residential settings are seeing the benefits of using the power of these cells.  Anyone willing to do a little research and take a little time can grasp the concept of photovoltaic cells.  Using the power of the sun through photovoltaic cells makes solar power a real possibility.