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S o l a r P o w e r D a i l y N e w s W e d n e s d a y, O c t o b e r 2 3 , 2 0 1 3 1 0 ASSESSING MODULE VULNERABILITY TO POTENTIAL INDUCED DEGRADATION IS KEY FOR RELIABILITY By Bengt Jaeckel, Principal Engineer, UL LLC and Ken Boyce, Principal Engineer Manager, UL LLC The use of solar power continues to grow at a healthy rate, and this trend is expect- ed to continue as the underlying costs of PV energy are expected to become more favorable. To support continued growth, the solar industry is working to ensure PV systems are a sound investment. PV module manufacturers, installers, EPCs, investors and project owners are all interested in the long term performance of PV installations. The reli- ability of the installation secures return of investment and profit. However, a PV installation will generate high yields only if all components, from the solar cell all the way to the grid, are working at their optimum performance level and the sys- tem is properly maintained. Solar product research, testing methodologies, and standards continue to evolve to meet this fundamental need. For example, tests that identify suscepti- bility to potential induced degradation (PID) have expanded knowledge regard- ing practical module performance. In recent years, several failure modes of PV modules operated under high potentials were observed. One important root cause, PID of crystalline PV modules, is a shunting mechanism which can cause dramatic power losses in higher voltage systems, sometimes in just one month. Creating a scientifi- cally sound test procedure for advance screening of modules for vulnerability to PID is critical to predicting system performance. At UL, we have consolidated sev- eral years of PV industry research to develop a unique and proven PID test- ing method. It is innovative in both its completeness and its simplicity. Our testing protocol is able to detect minor changes in cell manufacture, thereby promoting more objective and repro- ducible results. The method provides useful information quickly, and is eas- ier and less costly than other testing methods. Proactive assessment of PID susceptibility is one important element of a holistic understanding of PV sys- tem optimization, preventing unex- pected shortcomings in performance. UL is committed to supporting safe and sustainable advancement of renewable energy markets and indus- tries. For solar energy, this means moving forward with fundamental dis- covery, progressive testing methodolo- gies, innovative product support and detailed standards. These efforts sup- port the development of information for the solar industry about the safety, performance and reliability of PV equipment and systems. For more information, visit www.ul.com, call 877-UL-HELPS, email ULHelps@ul.com, or stop by booth 1821 at Solar Power International. UNIQUE FILTERS DESIGNED BY OAI FOR APPLICATION SPECIFIC SOLAR SIMULATORS OAI, a leader in solar simulation and I-V test, with over 40 years of optical design experience, has developed a new line of optical filters for its Class AAA Solar Simulators. Each filter is designed to match a specific cell type, such as Dye Sensitive (DSSC), Organic (OPV), Multijunction, High Efficiency, and Concentrated Photovoltaic (CPV). "OAI has always worked with its customers to develop unique solutions to their optical problems," said Dr. Charles Turk, President of OAI. "These new filters are easily added to OAI's standard Class AAA solar Simulators, giving the user the most flexible and versatile test sys- tem," he added. OAI's Class AAA Solar Simulators include Advanced Uniform Beam Optics and come standard with Air Mass 1.5 Global filters. Other air mass filters are available as an option. OAI's application specific Solar Simulators can be upgraded to include constant power and constant intensity when the optical feedback circuitry is included. A variable power supply allows the beam intensity to be adjust- ed from 0 to 1.1 suns. All Solar Simulators are easily integrated with OAI's I-V test systems and its advanced I-V Rider Software, thus com- prising the most complete application specific Solar Simulators in the industry. OAI has also expanded its manufac- turing facility to meet the increased demand for its application specific Solar Simulators. Additionally, OAI has installed a PV/Solar Test Lab in its San Jose, Calif. facility and offers this test facility to companies to test the applica- tion specific Solar Simulators or to develop performance data on their specific cells. OAI offers its customers opti- cal modeling, automation, and equipment to enable compa- nies to transition into production. OAI maintains its manufacturing and engi- neering in San Jose. For more information, contact OAI at 408-232-0600, online at www.oainet.com or by email at sales@oainet.com. BRONKHORST: EXPERTISE IN GAS, LIQUID AND VAPOR FLOW CONTROL The process of silicon or thin film photo- voltaic solar cells requires precise and reli- able gas and vapor flow control. Bronkhorst ® has over 30 years of experi- ence supplying mass flow control solu- tions for many different applications with- in such markets as semiconductor, chemi- cal and solar industries. Its instruments are made to a customers' specification, in whichever style is suitable, for laboratory, industrial systems or OEM installations. In PV production, thousands of Bronkhorst thermal mass flow meters/controllers are used for accurate, repeatable con- trol of inert gases such as nitrogen, hydrogen and argon as well as handling reactive gases such as oxygen, carbon dioxide and methane, cover- ing flow rates from 1 sccm to 6000 scfm (Full Scale val- ues). Bronkhorst's thermal mass flow sensors are used in combination with uniquely shaped laminar flow elements, offering high accuracy and excellent temperature stability. Instruments of our Select series can be offered with optional Multi Gas/Multi Range func- tionality. This option offers Continued on Page 18