What is Solar Panel Efficiency?

Where efficiency factors relating to electrical power derived from solar energy versus what the electricity provider bills you for every month is concerned, efficiency is typically measured by how the actual power output compares to the input and related costs involved.  In other words, can you derive enough power so that it exceeds the cost of the equipment and the service involved to capture what is necessary to generate the energy required to create electricity (i.e. the sun’s heat and light)? That depends on a number of aspects.

For instance, are you comparing input costs to actual energy output? If it isn’t possible to measure both aspects, start with what you can determine as being measurable, such as sunlight.  This equates to the amount of sunlight that you can capture throughout the day based on climate conditions and time of the year.  Suffice it to say, the input can be just as measurable as the output if you know what you are doing and have the right tools to do the measuring with.

Theoretical Implications

Solar energy efficiency can be measured in numerous ways according to theoretical work that has been conducted in high-tech labs.  It has been determined that the different technologies involved in the creation of the different types of solar cells will influence the efficiency factor.  Certain materials come into play as well.  It is these materials and technologies that influence how much sunlight is converted into electricity.

Scientists can theoretically test solar panel efficiency so easily because it is conducted in a laboratory under controlled conditions rather than on site in real life.  The reality is, they may rate one panel over another where efficiency is concerned based on a lab comparison.  However, when you put them side by side in a field test, it may be the other way around.  The big name manufacturers would have you believe that paying a bigger price for their solar panels equates to receiving bigger benefits where the efficiency factor is concerned.

Remember that when solar panels are tested in a lab instead of the field, the angle of the light is controlled unlike what really happens with the sun outdoors.  Another factor that affects efficiency is the temperature.  Solar panels manufactured out of crystalline silicon operate the most efficiently once they reach a temperature of 482° F (250° C).

Efficiency differences based on type of solar panel

There are basically 3 different types of solar panels on the market today, each of which has a different efficiency rating.  The following are the 3 types and their efficiency ratings:

Monocrystalline Silicon – manufactured using a single crystal of silicon which has been cut into a prescribed shape, this type of solar panel has a 13% conversion rate, meaning that it converts 13% of the captured sunlight into electricity.

Polycrystalline Silicon – these are less expensive and have a lower conversion rate because of the multiple crystal manufacturing process.  This increases internal resistance between the silicon crystals.  The conversion rate of these panels is around 12% to 12½%.

Thin Film Amorphous Silicon – probably the cheapest solar panel to produce and the least efficient at a rate of only 6% to 8%.  More suited for use in cooler and tropical climates, this type of solar panel is not very efficient in arid, hot climates.

 

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