In most businesses, competitors tend to soften their comments about one another.
That's the not the case in inverters and solar electronics.
"I don't get it," said Raghu Belur, co-founder of microinverter maker Enphase Energy, when
asked about companies that want to popularize DC maximizers for improving how centralized
inverters work during an interview at the Solar Industry Summit this week. "I simply don't
get it."
Companies that specialize in central inverters like SMA and microinverter specialists like
SolarBridge and Enphase are locked in a battle over the future of solar electronics.
Microinverter champions say that their technology works better and costs less in any type of
solar installation of any size, anywhere in the world.
Enphase has a pending third-generation product, for instance, that achieves efficiencies in
the 96-percent-plus range and will be capable of being installed at utility-scale sites. The
company is also looking at advanced AC-DC materials like gallium nitride, a material promoted
by Transphorm, and more silicon carbine.
In a few years, a microinverter could consist of three components and need very little copper
and other raw materials, Belur speculated. This will allow the industry to ride the Moore's
Law cost curve down. Dick Swanson, the keynote speaker at the event, said that the SunShot
program sponsored by the Department of Energy seeks to get solar down to $1 a watt installed:
in that scenario, only ten cents could be allocated to inverters.
Centralized inverter advocates, meanwhile, argue that they too are driving down costs and
looking at advanced materials. Some of the efficiencies obtained through microinverters with
things like DC maximizers. Most centralized inverter makers (including SMA) have actually
laid plans to make microinverters, but they generally believe that microinverters will
largely be confined to the residential market.
More importantly, central inverter advocates say that microinverters create risk. Instead of
having a centralized box, microinverters force solar installers to put 20 to 30 times the
number of devices into the field, which means more potential points of failure.
"If reliability is compromised, it will hurt the entire industry," said Jurgen Krenkhe,
president and general manager of SMA America.
Ken Christensen of central inverter maker Advanced Energy added that central inverters hit
efficiencies in the 97-percent-plus range.
Luckily, as interviews and panel discussions proved, the two sides aren't afraid to air their
differences.
"There is this idea that centralized inverters are more reliable, but the data doesn't
support that," said John Berdner, general manager of North America for SolarEdge during a
panel discussion. "This idea is simply not true."
Berdner cited a study from SunEdison that showed that central inverters exhibited a
reliability of under 50 percent, while string and microinverters were 95 percent reliable.
Part of the problem stems from how these products are made. Microinverters are produced on
manufacturing lines, while centralized inverters are largely hand-assembled.
"Reliability" in the study referred to the number of times a service call was made and did
not necessarily account for every actual breakdown. And speaking of data, Krenkhe added that
microinverters have only been in volume production for about two years.
"To look at six, nine or twelve months of data is a snapshot," he said.
That comment prompted Barry Cinnamon, CEO of Westinghouse Solar, to pop open his laptop and
show me data. (Cinnamon wasn't on the panel. He just happened to be sitting next to me in the
audience.)
Over a two-year period, Westinghouse/Akeena Solar installed 10,630 microinverters, of which
22 had to be replaced. The company also installed 3,373 centralized inverters; 318 had to be
repaired. The microinverter-powered systems lost 528 hours of power production. The central
inverter systems lost 464,000 hours. (Side note: Cinnamon noted at SMA had the far lowest
failure rate.)
The disparity in hours of power production lost comes because in a centralized inverter
system, the entire solar array goes down if the inverter does. In a microinverter system,
only individual panels are temporarily off-line.
In response, Jeff Krisa, vice president of sales and marketing at Tigo Energy, which makes DC
maximizers that link to centralized inverters, noted that a lot of residential installers
like microinverters. DC maximizers are just beginning to be introduced.
Who's right? The data over the next few years will tell the tale. Microinverters are
definitely gaining ground -- Enphase claims a 13 percent market share in recent California
residential installations. The company also gives a 15-year warranty and claims its
microinverters will last far longer. Still, the products are only a few years old and the
solar industry is notoriously conservative.
没有评论:
发表评论