The PV Module Index: Two solar module brands top the lists for reliability, performance, and quality

PV module index

Solar industry success is only possible when solar installers, EPCs and developers procure reliable, high quality products, which is why we’re excited about this first annual PV Module Index from the Renewable Energy Test Center (RETC). The report is a comprehensive assessment of top-performing modules that are tested for reliability, performance, and quality across 18 different indicators. Within the data, two manufacturers — Panasonic and LONGi  — are recognized for demonstrating high achievement across indicators in all three categories.

“RETC is releasing this index to help the entire solar industry better evaluate modules based on important attributes beyond efficiency and cost,” said Cherif Kedir, RETC President and Chief Executive Officer. “It’s worth noting that high achieving quality module manufacturers put their products through an exhaustive set of accelerated reliability tests, while other manufacturers choose to select only a few of the tests to characterize their products. We congratulate the high achievers in each of the categories, and look forward to working with all manufacturers to continue to demonstrate their product excellence.”


In 2018, RETC tested more than 2,500 individual modules, from more than 150 different module families, made by 46 different suppliers. While RETC evaluated modules on 18 different criteria, the report focuses on eight important criteria that best represent the three categories of reliability, performance, and quality. The report calls out high achieving modules that demonstrated results at the top of the distribution for each of the eight criteria.

“As the industry has matured, solar professionals may want to focus on the cost per watt, but modules with the lowest price are not always top values in performance, quality or reliability,” said Chris Beitel, Head of Business Development at RETC. “By focusing on all three categories, module manufacturers can have confidence their products are well-equipped to perform across the board, while downstream players can feel assured the products they are selecting are engineered to deliver as expected.”

[button link=””]Don’t miss our Solar + Storage issue in July — subscribe to Solar Builder magazine (print or digital) for FREE today[/button]

The report provides data showing test results for modules that achieved results at the top of the distribution. The paper also shares data on new technologies, such as bifacial and PERC, more recent entrants to manufacturing, and the differences between laboratory testing and real-world field performance and reliability testing.

Here is a quick look at the tests performed and some of the high achievers in different categories. Be sure to get the full report


The PV Module Index reviews the results of module tests such as Damp Heat, Dynamic Mechanical Load, and Potential Induced Degradation. High achieving modules withstood abuse from these tests and saw minimal degradation in power output, versus their peers.

  • Damp heat high achievers: Jinko Solar and Longi Green Energy Technology.
  • Dynamic mechanical load: Manufacturers achieving lower than 1% of degradation in the DML test: Canadian Solar, CertainTeed, Hanwha Q CELLS, Jinko Solar, Longi Green Energy Technology, Mission Solar, Panasonic, and Trina Solar.
  • PID: The manufacturers who achieved in the Top 50%, less than 1.0% degradation through 196 hours of testing: Jinko Solar, Longi Green Energy Technology, Merlin Solar, Panasonic, and Solar Frontier.


These tests measure a module’s efficiency in power generation and see how they do in actual real-world conditions, such as high temperatures, and early morning and afternoon sun conditions. Tests conducted include I-V Characterization of Module Efficiencies, conditions at elevated temperatures such as PVUSA Test Conditions (PTC), and Pan File Testing, which evaluates modules in various light and temperature conditions. Seven high achievers demonstrated greater than 19 percent module efficiency.

  • Manufacturers that achieved greater than 19% total area module efficiency in 2018 include Hanwha Q CELLS, JA Solar, Longi Green Energy Technology, Panasonic, Solaria, Sunpreme, and Yingli.
  • Four high achievers received Performance Ratios above 85 percent by demonstrating simulated performance, via PVsyst software, which was 85 percent of their “nameplate,” or theoretical maximum output: JA Solar, Jinko Solar, LG, and Longi Green Energy Technology.

Commitment to quality

These tests indicate a manufacturer’s strict adherence to high-quality standards in their R&D process, engineering changes, manufacturing and vendor management. Quality products should be well manufactured with repeatable processes, materials, production equipment, and labor techniques.

To demonstrate quality, the PV Module Index provides an exhaustive characterization of a module family across a multitude of tests to develop its Product Qualification Program/Thresher Performance Matrix. Degradation of less than 2% for a given test demonstrates high achievement and four manufacturers reached this level of performance.

Additional tests that are discussed in the report that covers reliability include Humidity Freeze, Thermal Cycling and Ultraviolet Exposure. In performance, other tests include Incidence Angle Modifiers and Light and Elevated Temperature Degradation. Finally, in the area of quality, additional tests in the report cover Engineering Changes, Bill of Material Changes, Randomized Sampling, Factory Audits, and Factory Inspections.

The tests were completed at sites in Fremont, California; Pahrump, Nevada; Los Andes, Chile and in Cagayan de Oro City, in the Philippines.

Have you checked out our YouTube page?

We have a ton video interviews and additional content on our YouTube page. Recently we debuted Power Forward! -- a collaboration with BayWa r.e. to discuss higher level industry topics as well as best practices / trends for running a solar business today.

Our longer running side project is The Pitch -- in which we have awkward discussions with solar manufacturers and suppliers about their new technology and ideas so that you don't have to. We discuss everything from residential rail-less deck attaching and home solar financing to large-scale energy storage value stacking and utility-driven new home solar + storage microgrids.

Tags: , ,
  • -8
  • June 4, 2019 16:49:05

    How Come SunPower wasn’t included in this test… the best panel rated doesn’t exceed SunPower’s 327 ACM and the 370 ACM is 22+ efficient… a highly popular panel, SunPower is a DG leader in the US yet does not appear to be included.