photovoltaic panels-photovoltaic cell-Some Observations on Photovoltaic Cell Panels
by Oliver Seely photovoltaic panels-photovoltaic cell
The text and photos on this page are in the public domain. Copying is encouraged!
photovoltaic panels-photovoltaic cell
Revised November 6, 2008
Introduction
For many years I've taught a course on science and technology from a historical perspective. The voracious appetite for energy by advanced societies and particularly the United States figures prominently in the course. I comment each semester that when humans are forced finally to stop using fossil fuels, either because of increasing costs or global pollution, there will still be plenty of energy from the sun, particularly in regions lucky enough to have cloudless days most of the year. One day my wife said to me, "Why don't you put your money where your mouth is?" So I did.photovoltaic panels-photovoltaic cell
The decision to install photovoltaic cell panels hinges on where one lives. The amount of sunlight as determined by the climate of one's location and the ability to receive the direct rays of the sun when it is shining helps one to decide if it makes sense to install the panels. On the left and right are images showing available sunlight for the United States and the world respectively. Although our location appears to be ideal because of the available sunlight per year, in actual fact our distance from the Pacific Ocean is only 12 km and coastal fog is a problem part of the year. On the average, the amount of sunlight we get is limited to between 5 and 8 hours per day throughout the year (see the blue strip along the coast in the left image in front of the arrow tip).photovoltaic panels-photovoltaic cell
Here is another image of the continental United States with a legend including units of kilowatt hours per square meter per day.
photovoltaic panels-photovoltaic cell
A roof sloping toward the south in full view of the sky would be ideal. However, our roof line slopes toward the east and the west. There is a chimney near the peak, as you can see.The panels have to be installed where there are no shadows during the day, so we installed our 2.5 kilowatt system on the east-sloping roof with an additional tilt toward the south. There are actually 18 panels each rated at 165 watts which brings the system to a theoretical maximum power output of 2970 watts or 2.97 kilowatts. The rating of 2.5 kilowatts may be due to the installing company knowing that the tilt of our panels would be less than ideal. Maximum output occurs around 11 am each day that the sun shines.
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