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Solar Panel Efficiency and Ranking PV Modules


Photovoltaic research and design over the past 18 months has resulted in historic advances in efficiency and technology.  During the years 2007-2011, research labs made strong headway in the race to improve solar panel efficiency.  The solar industry’s challenge has always been to develop the smallest, most efficient and least expensive device possible.  It’s the same concept that was employed successfully by the computer industry.   

As we move into 2013, solar panels have reached an average efficiency of around 15-17percent.  This is a strong improvement over past efficiencies existing just three years ago, and is the result of millions of dollars and countless hours of research and development.  Solar panel manufacturers have recently been pulling back on research and development.  They are now concerned with selling their existing designs, which are now at extremely affordable prices.  The market does not anticipate any significant increases in efficiencies for many years to come.


Consumers interested in photovoltaic solar installation have been at a disadvantage as PV cells have not been easy to compare to each other.  Because they are a relatively new technology, cells are often sold based on productivity or longevity and it has been nearly impossible to rate or rank solar panels across the spectrum. 


The Principal Solar Institute (PSI), a publicly traded company aimed at providing cutting edge information to the solar industry, has developed a universal rating PV module rating system.


“Until now, there was no accepted standard for comparing the critical characteristics of PV modules between different manufacturers, or even across a single product line,” says Matthew A. Thompson, Ph.D., executive director of the Principal Solar Institute. “The PSI Ratings elevate the solar industry in a rigorous approach similar to the financial sector, which turns to Standard and Poor’s Ratings for investments, and the air conditioning industry, which relies upon SEER Ratings. We are closing the gap in the solar power industry’s urgent need for a method to uniformly evaluate PV modules in order to make technologically and financially optimal decisions.”


Per their website, the rating system is rigorous and looks at the following attributes:

  • Actual Tested Maximum Power vs. Advertised

  • Temperature Coefficient at Maximum Power

  • Power at Low Irradiance to Power at High Irradiance Ratio

  • Normal Operating Cell Temperature (NOCT)

  • Total Area Efficiency

  • Negative Power Tolerance

  • Annual Power Reduction


So what are the results?  Here is a very comprehensive list of PV modules and how they compare to each other. Go take a look and see what modules will work well for you and then give us a call so we can discuss putting a system on your roof.


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