Most solar photovoltaic systems convert the direct current (DC) electricity produced by PV panels into the alternating current (AC) used in homes and businesses with inverters, which can be centralized or set up in strings depending on the size of the array. There are also microinverters, which are attached to each panel and convert the electricity into AC current at each panel. Such systems are typically used on home or small commercial operations. But now that Vine Fresh Produce in Ontario, Canada has installed a 2.3 megawatt solar rooftop array on its greenhouse using Enphase microinverters, that may be set to change.
Microinverters have some advantages over traditional inverters. Since they’re attached to each module and convert the power produced by each one, every solar panel in the array can produce the maximum amount of energy possible. With traditional inverter installations, the inverter produces AC current at a rate that’s based on the PV module in the array that’s producing the least amount of electricity. So if a panel is broken or shaded, the whole array can produce far less electricity than it’s capable of.
In a microinverter array, each module can perform to its best ability—and if one isn’t working it can quickly be identified or replaced if necessary. However, microinverters have a slightly higher up-front cost than traditional inverter-based systems, which is one of the reasons why they haven’t been deployed in larger solar power arrays.
The cost of microinverters is coming down and if larger systems such as the Vine Fresh array installed by Sentinel Solar prove to produce more electricity than similar systems with centralized inverters, they’re likely to win over more critics. “This milestone project is Enphase’s largest announced to date,” said Jeff Loebbaka, Enphase senior vice president of Worldwide Sales and Field Operations. “We are proud to work with Sentinel Solar, our oldest partner in Canada, to help make solar history for Ontario and for Enphase,” he added.
“We have been fortunate to represent Enphase from the start in the Canadian market,” said Adam Webb, president of Sentinel Solar. “By designing the system around Enphase we were able to complete the project on time and on budget. This installation is the result of a year’s hard work by our team and partners and is one of many Sentinel-designed commercial installations.”
The system, which consists of more than 9,000 microinverters and modules, also qualified for Ontario’s feed-in tariff (FiT) since Enphase has a manufacturing facility in the province. The Chinese-made Jinko solar modules wouldn’t have qualified for the incentive program.
The array is also unique in that it replaces part of the greenhouse’s roof, leaving the underside of each module exposed where Sentinel and Vine Fresh has easy access to each module and microinverter. That way the system can be maintained without getting up on roof, particularly because the greenhouse uses glass panes for its roof.