On October 22, the Department of Energy announced $60M in new awards to drive affordable, efficient solar power. The SunShot Physics of Reliability: Evaluating Design Insights for Component Technologies in Solar (PREDICTS) program is taking a physics- and chemistry-based approach to identifying solar product failure modes.
Module-level (~200 W) power electronics (MLPE), such as microinverters, microconverters, and DC power optimizers, offer advantages in safety, system operations and maintenance (O&M), energy yield, and component lifetime due to their smaller size, lower power handling requirements, and module-level power point tracking and monitoring capability. However, they must endure more extreme environments, reducing their reliability. Because solar installations can have tens of thousands to millions of modules (and as many MLPE units), it can also be difficult (or impossible) to track and repair units as they go out of service. Therefore, understanding each device’s statistical reliability and extending unit lifetime are critically important to a large solar installation’s O&M scheme.
Most photovoltaic (PV) research has focused on module efficiency and reliability, largely ignoring these issues with regard to balance-of-system components. The PV PE industry does not have the extensive, standardized reliability measuring accelerated lifetime tests (ALTs) that exist in the module industry or other more mature PE industries (e.g., automotive). By recommending standard ALTs that have been thoroughly correlated to fielded MLPE failure rates, modes, and environmental stressors, the confidence of system operators, integrators, manufacturers, and financiers is increased—decreasing the cost of financing and operating large solar installations.
Sandia will lead a “Module level power electronics reliability and accelerated testing standards development” project to conduct R&D to create technically sound, vendor-neutral and technology-neutral reliability standards for stand-alone and module-integrated PV microinverters and microconverters by
- obtaining field-use data/samples from stakeholders,
- performing failure analysis to determine field-failure mechanisms,
- developing ALT parameters to cause field-failure mechanisms,
- ensuring that test failure modes in ALTs are same as in field,
- performing ALTs,
- determining acceleration factors for tests, and
- using a stakeholder group to draft standard reliability test protocols based in accelerated test data that has been validated by field-use data.
The approach synthesizes domain expertise, failure mode and effects analysis, physics-of-failure determination, physical modeling, field stressor data, field reliability statistics, and accelerated laboratory testing to inform draft standards that will reduce technology risk and guide future product development.
By having a standard reliability test protocol, which is firmly based in field-use data, manufacturers can reasonably predict the future field-use lifetime/reliability of an unknown device. Meanwhile, due to the use of accelerated testing, the confidence of PV owners, operators, and financiers is increased, decreasing the overall costs of PV facilities’ operations and maintenance.
The successful development and widespread adoption of standard reliability test protocols for any industry is dependent on stakeholder engagement and correlation to real-world failure modes. Sandia will work with TÜV Rheinland PTL, LLC; Arizona State University; University of Utah; Robert Bosch, LLC; and ViaSol Energy Solutions in this SunShot project.