We think photovoltaic or PV cells as a modern invention. But did you know that the photovoltaic effect was first recognized in 1839 by a French physicist? Did you also know that the first solar cell was built in 1883?
How about this. Did you know that Albert Einstein won the Nobel Prize for Physics in 1921 for his explanation of the photovoltaic effect? So now that you amaze your friends and confound your critics with your knowledge of the history of PV cells, how are you going to make your life better with that knowledge?
Of course, one way to improve your life is more efficient life. And that brings us to the issue of the photovoltaic efficiency. Charles Fritt original 1883 cell was only 1% efficient. It was only in 1946 that Russell Ohl patented the current, much more efficient form of solar cells using doped silicon.
Now that you’re all this background and notify you of efficiency, there is one unusual factor in the efficiency equation for solar cells. Efficiency is usually described as the cost of a product. How do you describe the efficiency of a PV cell when the cost of the main ingredient, sunlight, is free?
Although sunlight is free, through a solar cell electricity is not free, because to produce a defined cost to the cell itself. Also, the cost of a location for the panel to absorb sunlight. If the cost of the panel to the cost of the location, now has the half of the equation. The other half of the equation is the output, usually expressed in watts.
So now you have it. The less your panel location, and cost in comparison with the output, the greater the photovoltaic efficiency.
Source: http://ezinearticles.com/?Photovoltaic-Efficiency&id=3770528 by Curtis Murchison