A five-year study conducted by Sandia Labs on the degradation of solar modules shows that 13 of the 23 types of modules tested have an effective life of more than 30 years.
A team led by photovoltaic researchers from Sandia carried out a Five-year study of the degradation of 834 photovoltaic modules in the field, representing 13 module types from seven manufacturers in three climates. Its objective was to quantify the degradation rates of recent and widely used photovoltaic technologies and to publicly report the results to inform stakeholders and best practices.
The article Progress in photovoltaics The team presents the results of their study and represents years of work at Sandia’s Photovoltaic Systems Evaluation Laboratory and associated laboratories at the National Renewable Energy Laboratory and the University of Central Florida.
The PV market is constantly evolving and long-term field data on these new technologies is lacking, raising the question of whether or not sustainability has been affected. Purchasing PV modules directly from the open market allows us to perform unbiased analysis and inform the ubiquitous public by also publishing the data.
The partnership with the NREL and the UCF was essential for a study of this type because it allowed us to install identical systems in different climates and to characterize them according to a well-controlled and harmonized measurement plan.
Marios Theristis, team leader.
According to the researchers, the cost of PV modules has dropped dramatically (up to 85% according to a recent NREL report) over the past decadethrough economies of scale, use of new, more efficient cell designs, automation of production lines, larger modules and changes in bill of materials such as thinner glasses and frames, new encapsulants and backsheets, etc.
However, these Changes in module design and materials could affect durability and reliability, and the levelized cost of electricity is sensitive to the rate of power degradation. As power degradation increases, the levelized cost of electricity increases and system life decreases.
Scientists measured the performance degradation of photovoltaic modules installed in New Mexico, Colorado and Florida. They measured performance under standard test conditions at the start of the study, examined initial power stabilization, and periodically retested the modules over the next five years to monitor degradation rates over time.
They checked that degradation rates are very non-linear over time and some types of modules exhibit seasonal variations. The average and median values of the degradation rate of -0.6% per year were consistent with the rates measured in the older modules. Of the 23 systems studied, six had degradation rates that would exceed warranty limits in the future, while 13 demonstrated the potential to achieve a useful life of more than 30 years, assuming that trends in degradation rates have stabilized.
This is an encouraging result. With the increase in photovoltaic installations, consumers and other interested parties will be interested to know that the sustainability of photovoltaics appears to be consistent in the face of rapid technological improvements and cost reductions. However, it is also concerning that 26% of systems exceed warranty limits. Opportunities still exist to reduce degradation rates to levels that allow for even longer useful life of PV modules. For example, for a useful life of 35 and 50 years, PV modules are expected to operate with degradation rate values greater than -0.55% per year and -0.4% per year, respectively.
The scientists also raised important talking points. How the rate of degradation is set, either relative to specifications or the initial post-stabilization rate, can influence the resulting rate. This resulting index can have a significant influence on purchase costs, warranty and insurance claims or feasibility studies for project financing.
Marios noted that consumers and parties interested in learning more about the tested modules will soon be able to see all of the flash test data collected at Sandia, the National Renewable Energy Laboratory and the Florida Solar Energy Center at the University of Florida. .
This study is an excellent example of how national laboratories are collaborating with universities to answer critical questions about the sustainability of solar energy technologies. Few institutions are able to support long-term experiments involving such a large number of modules.
Sandia Principal Scientist Joshua Stein.
We continue to deploy new technologies as they become available in the market. Therefore, we will continue to report on all stages of PV life, and we will also leverage field measurements, as well as image data, to assign attributes to what is driving degradation and why.