Solar cell efficiency is a percentage which describes how much solar energy a given solar cell can convert into electricity. There are many different factors that go into the efficiency of a solar cell, or photovoltaic cell, such as the materials they are constructed of, the angle of the solar cells relative to the sun, and the strength of the sun at any given time and place.

Calculating solar cell efficiency is done indirectly, by measuring thermodynamic efficiency, quantum efficiency, VOC ratio, and fill factor. The measurement is done indirectly because three of the main determining factors, reflectance efficiency, charge carrier separation efficiency, and conductive efficiency, are too difficult to measure with reliable accuracy.

Efficiency Tables

Solar cell efficiency tables are published works which layout the specific efficiency of various solar cells. They have become a helpful and necessary part of the study of solar cell efficiency because of the wide range of materials available and construction
methods used to build solar cells.

In order to continue making cheap solar panels, manufacturers require this data. Rather than spending money on research and development, many manufacturers have relied upon academia to research new materials and assembly methods to make their solar cells more efficient. There are many different versions of solar cell efficiency tables, and they all have version numbers to help you differentiate between tables.

Efficiency Record

The record for efficiency in photovoltaic cells, or solar cells, unofficially, is less than 30%. A company named Suntech recently announced the release of the most efficient mass-producible solar cell available, reaching 20.3% efficiency. However, in laboratory produced solar cells, efficiency levels have reached 27.6%, according to Alta Devices, a Santa Clara, CA based startup.

The highest possible efficiency level is 93% due to the “Carnot limit”, which takes into account the temperature of the photons coming from the sun. New efficiency records are made and broken on a regular basis as the quest for the most efficient solar
continues on.

Efficiency Equation

The equation for solar cell efficiency is as follows:


In this equation, ‘n’ stands for a solar cell’s energy conversion efficiency, Psub(m) is the maximum power point, ‘E’ is the input light irradiance and the Asub(c) is the surface area of the solar cell.

Each of those variables must also be calculated on their own. Doing so requires expensive equipment and cannot be done with anything other than professional measurement tools.

Efficiency Chart

Solar cell efficiency charts help producers, consumers, and academics clearly compare various solar cells based on their efficiency. The charts label can sometimes be a misnomer, because many of the charts are actually line graphs which chart the various efficiencies. The photovoltaic cell efficiency charts came into existence as the realm of possible materials and construction methods expanded.

Efficiency vs. Temperature

A solar cell’s efficiency rating goes down the higher the temperature of the cell. This has been proven through numerous academic studies and through practical usage. In areas where solar energy is a popular choice and there are lots of solar roof panels, solar cells become less efficiency as the day progresses.

Solar cells reach their lowest efficiency rating at the hottest time of the day. Scientists and academics have found that adding cooling units to solar panels and solar cells helps improve their efficiency.

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