Blymyer Engineers is completing the designs on a 1,500-volt photovoltaic (PV) system in Florida that will generate 123.75 MW of power—a development that the company says could mark the beginning of an industrywide transition to 1,500-volt DC systems. The project, under development by Gulf Coast Solar, is utilizing 1,497,000 First Solar thin-film modules on AET fixed-tilt racks.

"We’re seeing the beginnings of a transition to 1,500-volt DC systems, which is a significant change for the market," says Mike Rantz, president of Blymyer Engineers. "There was a big movement from 600-volt to 1,000-volt systems in 2012 and 2013, and now we’re seeing another evolution to these 1,500-volt projects as the supply chain starts to scale and the high-voltage value proposition is recognized."

Prior to 2013, most PV systems in the U.S. were installed at 600 DC. Image credit: Pixabay.According to Rantz, in these higher-voltage projects, the balance of system (BOS) requirements are lower and strings are longer—allowing for fewer combiner boxes, less wiring and less trenching—all of which drive PV system costs down. "UL has updated many standards to provide a means for manufacturers to list their products in compliance with the [National Electrical Code], and we’ll see more of this as market demands brings these projects to the table,” he adds.

Prior to 2013, most of the systems in the U.S. were installed at 600 DC, while Europe was already comfortably working in 1,000 DC. Testing standards have been a barrier to 1,500-volt projects in the U.S., and the availability of 1,500-volt manufactured components has been limited. Now manufacturers throughout the supply chain are starting to cater to this voltage ramp-up, which lowers BOS costs and subsequently the levelized cost of electricity.

“Fifteen hundred-volt systems allow for a 50% increase in the number of modules on a string, and reduce the quantity of equipment used to aggregate the DC power of the array," notes Blymyer Director of Engineering Greg Mazur. "The higher voltage allows more power through equal-sized conductors. It results in less voltage drop, and the power electronics uptake much more efficiently. The upshot is we can design higher-voltage systems with longer strings; that’s where the cost savings in BOS kick in.”

Rantz says his company is already anticipating new developments in storage. "The near future might see the use of three-phase string inverters and utilization of next-generation silicon carbide components, which would allow for much greater power densities and switching frequencies,” he says.