Solar Cell Defects

In spite of the industry's push towards perfection, it is estimated that at least 1 to 2% of the solar panels in the world contain at least faulty solar cells. With a worldwide production of 130 GW in 2019, this means that at least 1.3 GW of modules with substandard solar cells could still find their way into the market.


Non-Defective Cells

Solar cells without any visible defects, no variations in colour and no bends are called Grade A cells. In these perfect cells, however, a slight bend of <= 2.0mm and a tiny colour deviation is permitted. Also the electrical data specified on the panel's spec sheet correspond to what will be obtained when measured with a cell testing equipment.

A Grade A Solar Cell (Source: SinoVoltaics.com)

Defective Cells

In severely defective cells, the electrical data would be off the specifications listed by the manufacturer when tested with an electrical equipment. Also, in defective cells, the following are visible.

  1. A slight bend of 2.0mm – 2.5mm

  2. Colour variation

  3. A visible yellow area that takes more than a quarter area of total on the surface

  4. Missing fingers

  5. Missing busbars

  6. Paste leakage

  7. Scratch of length between15-50mm

  8. Water marks.

Examples are shown below.

A Defective Cell Showing Colour Variation (Source: SinoVoltaics.com)
A Defective Cell Showing A Bend (Source: SinoVoltaics.com)
A Defective Cell Showing a Paste Leakage (Source: SinoVoltaics.com)
A Defective Cell Showing a Chipped Part (Source: SinoVoltaics.com)
A Defective Cell Showing Missing Fingers (Source: SinoVoltaics.com)
A Defective Cell Showing A Missing Busbar (Source: SinoVoltaics.com)
A Defective Cell Showing a Watermark (Source: SinoVoltaics.com)

Images Source: Dricus De Rooij (2013), Solar cell grading (A, B, C, D). Retrieved from https://sinovoltaics.com/quality-control/grading-of-solar-cells-a-b-c-d/ 

Solar cells are connected together to form modules which are encapsulated with an EVA film and assembled together into modules that are framed into panels. If the solar cells, being the most important part of the modules are low grade and defective, the panels themselves would be defective. These defective panels are constructed mostly with poor quality silicon wafers or 'seconds' that might have been rejected by top-quality manufacturers. They are mostly sold under false brand names.


Solar cells are the most important part of the module and there are quality control standards that serve as the minimum requirements for the approval of solar panel modules before being introduced into the market. A defect in a solar cell may not necessarily affect the electrical performance of its panel, but it will most certainly shorten its life. These requirements ensure that a manufacturer does not cut production costs on the solar cells and that a buyer's financial investment is secured. This is why it is best to invest in the best, trusted and reputable brands as a guarantee against potential financial losses.


SolarKobo helps its clients make the best possible choice of solar panels that suits their power needs and fits their budget.

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