Safeguarding Solar Power Innovation Through Reliability Testing


A recent report from the Solar Energy Industries Association (SEIA) states the third quarter of last year was the second largest quarter in the history of the U.S. solar market and the largest quarter ever for U.S. residential photovoltaic installations. And SEIA notes that 2013 may have been the first time in more than 15 years that the U.S. installed more solar capacity than the world leader, Germany.

Now that the growth prospect for the solar market is delivering against the longtime promise, the key focus for the industry must be on managing the next waves of innovation and the expected explosive growth by ensuring both quality and safety for energy users.

Going forward, the solar sector should extend even more focus on addressing PV systems as a sound investment. Product reliability plays a crucial role in the overall PV energy cost profile and return on initial investment. Conducting research and developing new and improving standards and testing methodologies for solar products help manufacturers better understand performance of their modules.
Building confidence
The Worldwatch Institute estimates that the price of meeting the world's energy demands will be $26.3 trillion through 2030 – an average of more than $1 trillion a year. On top of that, the U.S. Congressional Research Service found waste in the nation's electrical system costs roughly $500 billion a year.

There are no greater needs than the adoption of efficient and reliable renewable energy sources – and innovative energy technologies to support that adoption. Employing PV systems has the potential to dramatically improve the efficiency, reliability, economics and sustainability of energy services. Solar modules coupled with other energy innovations, such as smart grid technology, wind turbines, energy-storage devices and home energy management systems, change the power landscape, moving it toward a more sustainable future.

Still, this movement cannot take place unless there is confidence in the reliability and durability of renewable energy sources such as solar. Manufacturers, distributors and installers now participate in testing that helps determine the probability that a PV product will perform its intended function for a given period of time under a given set of conditions. This assessment will give manufacturers a better understanding of where and what product changes may be needed to meet regulatory requirements, user expectations, industry standards and a brand's own quality expectations.

Conducting comprehensive reliability testing enables the manufacturer to rectify potential defects before it is too late, allowing for the delivery of cleaner energy services to homes and businesses in a variety of locations throughout the country and world. This includes testing for environmental conditions such as extreme temperatures or humidity; mechanical tests addressing vibration, shock or impact; ingress protection; and combinations of the various stressors.

Additionally, what cannot be neglected in testing the reliability of PV systems is the everyday product performance. For manufacturers to assess long-term reliability, solar modules must undergo evaluation, simulating anticipated or accelerated conditions, in controlled laboratory settings.
Addressing concerns
With the surge in solar power came concerns over quality, reliability and safety in solar modules and their components. Some manufacturers have been challenged to maintain product quality as production levels and demands increase and as the supply chain continues to evolve.

An example of the solar industry's addressing limitations of some PV products on the market today is the adoption of a proven potential induced degradation (PID) susceptibility testing method, among other environmentally oriented testing. Conducting PID testing with appropriate methodologies helps ensure more objective and reproducible identification of PV module susceptibilities.

PID is a severe threat to PV module reliability because it can result in a power loss of nearly 100 % in modules at the end of a system string – a number of PV modules aligned in series – sometimes in just one month.

An example of an effective PID testing methodology is as follows:

The process begins by identifying any initial degradation from the test samples. No climate chamber is needed for temperature conditioning, which reduces costs. The test module's performance is measured and evaluated at a standard test condition of 1,000 W/minute and at low irradiance. This is used as the susceptible criteria because PID causes shunting of the solar cells, which results in a significant negative effect on the module's low-light behavior. A PV module is identified as PID susceptible if there is a power loss of 5% after 168 hours or a power loss of 10% after 336 hours.

Through this sort of testing, the industry will help ensure module reliability, and solar energy will continue to push forward as a clean, renewable source of energy utilized widely by consumers and businesses.

The rapid evolution of today's energy industry is increasing the demand for innovations in energy generation, distribution, management and usage. Solar energy has the potential to lead the revolution in energy, but work must be done to advance the safety and reliability of the new processes, technologies and products.

As a result of rising energy costs and a focus on reducing environmental impact, energy is now expected to be cleaner, as well as more reliable, efficient and secure. Overall, renewable energy such as solar is helping to advance markets and industries like never before. This is a transformative age, with new technologies and product developments arriving at an incredible pace. However, all innovation is met with emerging risks, and mitigating these risks is critical for the solar sector to further progress and finally meet its long-projected promise.

Evelyn Butler is UL's global business development director for its energy and industrial systems division, which includes PV / Solar, wind, inverters, generators, biofuels and traditional fuels.

Ken Boyce is UL's technical manager for energy technologies, overseeing standards development and technical operations for solar, wind, inverters, battery, biofuels and other renewable energy equipment and systems.

The authors can be reached by email at

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