New anti-reflective coatings could improve solar module performance enough to translate to millions of dollars for project developers and solar module manufacturers.
PV Evolution Laboratories (PVEL) has added two new solar module performance tests to measure this variable. PVEL measures a module’s output drop-off in the field as the sun crosses the sky and sunlight hits it at a wide range of angles (incidence angles). This allows for an accounting of output increases from new anti-reflective coatings that could improve performance as much as 1 percent.
For its light-induced degradation testing, PVEL obtains test samples from production lines at manufacturing facilities to make certain the tested modules have not been presoaked to minimize the measured degradation.
These new “performance characterization services” are significant steps for the young, relatively small lab toward matching the range of services offered by major international standards and testing entities like TUV Rheinland, Intertek, and Fraunhofer CSE. But there is a fundamental difference in PVEL’s business model, according to CEO Jenya Meydbray.
“Our objective is to support commercial transactions and projects in the downstream,” Meydbray explained. “These are things that influence the success of a project and the success of a panel manufacturer bidding on a project, rather than product certification.”
Assumptions about output dropoffs with varying incidence angles “for plain, flat-plate modules are not bad,” Meydbray said. “But with newly engineered anti-reflective coatings, the assumed losses of 6 percent to 8 percent are actually significantly less.”
Instead of making assumptions about the output of a solar plant that can cost “a lot of dollars,” Meydbray said, “we can measure the actual performance and use empirical test results in decisions about those dollars.”
An accurate assessment can change the forecasted energy output by up to 1 percent, Meydbray said. Over the 25-year life of the hundreds of thousands or millions of modules in a commercial or utility-scale solar project, a 1 percent increase can amount to a lot of money, even at a few cents per kilowatt-hour.
Another way to think about it, Meydbray said, is that it can affect a developer’s profitability by 10 percent. “Banks loan against future cash flow. If the future cash flow is bigger, they will loan more.”
A forecasted output for modules with anti-glare technology based on assumptions about modules without it “leaves up to 1 percent of the kilowatt-hours on the table,” Meydbray said. “Buyers make their decisions based on kilowatt-hours. For module manufacturers struggling with a tough marketplace, this can be a competitive advantage.”
Any crystalline silicon module’s output drops off during the first week of exposure to the sun, Meydbray explained. The purity of the silicon determines how much the LID is, but it ranges from 0.5 percent to 4 percent. Manufacturers can “game” the LID test by "presoaking" the module with light to diminish the drop-off in output, Meydbray added. To prevent this, PVEL is working with SolarBuyer, which does factory audits, to obtain test samples directly from the production line.
“If the assumption about LID is too conservative,” Meydbray said, “kilowatt-hours are once again left on the table, either by the buyer or the seller. And there is no reason to assume. We can measure it. In the past, larger margins made plus or minus 5 percent assumptions acceptable,” Meydbray said. “Today, assumptions aren’t good enough.”