On Aug. 31, Enphase released a new study showing that photovoltaic (PV) systems with Enphase microinverters are outperforming system output estimates by an average of 8 percent over what the National Renewable Energy Laboratory’s (NREL’s) PVWatts calculator project the systems should produce.
The company studied production data from more than 143 photovoltaic systems with Enphase microinverters.
“We worked with a handful of installer partners,” said Enphase Marketing Manager David Briggs, during a teleconference.
The systems were installed by Real Goods Solar, Solar Universe and Astrum Solar in California and the Eastern U.S.
“We took [into account] all available systems they had with Enphase,” he said. Then the company limited the study by a number of factors including that they had to be operational for at least six months to be included in the study. The average included systems that had been in the field for 12 months.
The Enphase microinverters performed 8 percent higher than the expected results in PVWatts, according to the study.
A prior study of other systems showed that the most systems performed at a level of roughly 8 percent below what PVWatts projected, Enphase said.
“A review of similar published PVWatts studies, such as the 2009 study authored by Gostein, et al., indicates that solar installations using traditional central inverters actually underperform PVWatts estimates by 8 percent on average,” the report said. “When considered together, these results indicate that Enphase Microinverters can improve the performance of solar installations by 16 percent on average.”
Part of the reason the microinverters are proving more efficiency is they convert the DC power produced by the panel to AC power at the panel level. Enphase said their latest microinverters are capable of operating at a 96 percent efficiency level. They also offer better reporting tools for system owners and installers. The inverters can communicate with both to tell them whether or not each module is operating correctly. If not, the module can be replaced.
Coinciding with the report, Enphase introduced a new tool in the company’s online monitoring service, Elighten. The tool compares the system owner’s array with the expected production projections from PVWatts, according to the company.
Astrum Solar offers Enphase microinverters on all of its arrays, according to Michelle Waldgeir, vice president of Marketing at Astrum. While the microinverters have a higher upfront cost, they end up paying for themselves over time.
“We show [potential customers] the value proposition and show them that microinverters save them money over time,” she said. “If you look at increased energy you’re getting, which drives savings on energy bills and reliability, over time, microinverters do well.”
Image courtesy of Enphase.