New Generation Inverters to Drive Down Cost of Solar Power: Interview with Silicon Valley’s ArrayPower

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Digital and solid state electronics are reshaping the way solar power systems are designed and built, holding out the promise of higher, more efficient performance at significantly lower cost and with a smaller footprint. This is especially true in the market for inverters, which convert direct current (DC) from modules or batteries to the alternating current (AC) used to light and power homes, buildings, appliances and industrial and commercial processes.

As auto manufacturers have done in recent decades, power inverter designers and manufacturers are increasingly using semiconductors and digital, solid state electronics rather than traditional electronic components to design and build power inverters, and they’re incorporating them into solar power modules themselves. They’re also redesigning the wiring and architecture of solar power arrays to increase system performance and efficiencies, as well as make it easier and less costly to install solar power systems capable of reliably supplying grid-ready, commercial-grade electricity.

Based in Sunnyvale, California, ArrayPower is one of a number of power inverter designer/manufacturers that’s taken advantage of Solar Power International (SPI) 2011 in Dallas this week to launch new product lines.

In ArrayPower’s case, that includes launching the ArrayPower Sequenced Inverter, as well as the start-up coming out of Silicon Valley “stealth mode.” Its Sequenced Inverter is the first in the world that reliably converts DC power to grid-ready, commercial-grade, three-phase sequenced AC, according to the company.

A Quintessential Silicon Valley Start-Up

The Antenna Group’s Tomi Maxted and Kimberly Setliff organized a Skype video interview for Clean Technica with ArrayPower CEO Wendy Arienzo and director of business development Nick Cravalho.

The creation of ArrayPower is the quintessential story of a Silicon Valley start-up as Ms. Arienzo describes it. Founded in 2008, the company’s origins go back to a Silicon Valley garage where a group of inventors with expertise in solar and power electronics and semiconductor technology joined in an effort “to perfect a completely novel approach to solar power conversion.”

Successful in their initial efforts, the company’s founders were able to attract seed capital from venture capital firms and attracted the interest of a California manufacturer of solar photovoltaic (PV) systems, one of the top 10 in the world. Arienzo and Cravalho left us guessing as to exactly which company this might be, as they were unable to disclose the name.

* Image courtesy of ArrayPower

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–> Page 2:  Module Design, & Reducing the Leveled Cost of Solar

Parallel, Decentralized, Built-In Module Design

Suffice to say that events gathered momentum from there. ArrayPower staff began working with the solar power systems manufacturer to fully integrate Array’s inverters with the company’s solar modules at its plant.

The result is the world’s first three-phase sequenced AC solar power inverter capable of providing grid-ready, commercial-grade power, according to Arienzo, one that increases efficiency, improves output performance, and enhances reliability and durability as compared to other inverters on the market. Solar power systems equipped with ArrayPower’s Sequenced Inverter will also prove to be a lot cheaper to install and maintain, she said.

Array’s use of semiconductor-based digital and solid state electronic components as opposed to traditional components comprised of metal and liquid electrochemical components, such as electrolytic capacitors, is one key to the advantages and benefits Array’s Sequenced Inverter. The inverters being incorporated into the solar modules at the factory, and the way in which modules and arrays are linked to form a solar power system are two others.

Incorporating the inverters in each module at the factory decentralizes the overall system architecture, resulting in more efficient and reliable electrical output. Connecting modules and arrays in parallel rather than in series also enables more modules to be grouped in larger arrays, which means less wiring and equipment. That translates into lower costs.

As is the case with modules connected in series, this enables the low voltage DC produced by solar modules to be stepped up to the higher voltages required for inverters to convert DC to AC, but connecting them in parallel results in improvements to overall power output and efficiency. Again, it also decentralizes the production of electricity, reducing or eliminating the possibility of a single point of failure compromising the overall system’s ability to produce grid-quality electricity.

Reducing Solar’s ‘Leveled Cost of Energy’

It’s this combination of elements – employing digital, semiconductor-based and solid state electronics to manufacture its inverters, integrating them with solar modules during module manufacturing and wiring solar power modules and arrays in parallel – that Array believes will help drive down solar power systems’ “Leveled Cost of Energy” (LCOE).

Likewise, it’s these elements, coupled with ArrayPower’s proprietary inverter design – the company’s been granted six patents and has another 37 in the pipeline – that leads management to believe that they’re a step ahead of the competition, at least for the moment.

“We’re very happy regarding how we’re positioned at the moment,” business development director Nick Cravalho told Clean Technica. “We’re really the first integrated, three-phase sequenced AC inverter on the commercial market…We’re gaining market traction, the technology is in the field, we’re getting real data and our partners are now actively selling the technology.”

An Organization ‘Light on its Feet’

As an organization, ArrayPower’s designed and built to be “light on its feet,” with minimal operating overhead, and to be able to scale up volumes quickly, Arienzo explained. “We’re completely focused on delivering high performance, reliability, durability at the right price point [to the commercial market],” Cravalho added.

One key to this is a business model focused on selling directly to module manufacturers. Another is contracting with a global manufacturer headquartered in the US to have its inverters manufactured offshore Singapore on the nearby Indonesian island of Bataan. Its cable harnesses are manufactured in Europe.

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–> Page 3: Going to Market

Commercial Market Focus

In contrast to most micro-inverter companies, which are focused on the residential market, ArrayPower’s business strategy is built around meeting the needs of the commercial solar power market, which makes up 65 percent or so of the overall market, Cravalho explained.

Array’s raised $22 million in capital in ‘A’ and ‘B’ financing rounds from venture capital firms including VC heavyweight Draper Fisher Jurvetson (DFJ) and Trident Capital, Arienzo continued.

“We see the commercial market certainly as the largest market segment in the US, but it’s also growing rapidly on a global basis. We expect to be in Europe next year,” she said.

The company’s also looking to diversify use of its Sequenced Inverters more broadly, moving into other power market segments come 2013. “We could play well with batteries,” Arienzo offered as a for-instance.

Nearer term, management’s focus in on further refining and improving the performance of its inverters and on “working with our existing partner to accelerate downstream adoption with installers,” Cravalho said.

Out in the Field

Array’s Sequenced Inverters are installed in a number of field trials. One is a 30-kilowatt (kW) site in Morbach, Germany outside of Frankfurt. It has several in California, another 7-kW system at a high desert site in Davis, another live 7-kW field trial with an early adopter at a commercial site in San Jose, and another on the company’s Sunnyvale headquarters.

It’s also been working with PV Evolution Labs (PVEL) in Berkeley and has partnered with Fraunhofer for the performance of its Sequenced Inverters to be monitored and evaluated. “They’ve been outperforming” expectations so far, Arienzo said.

Over the next six months, the company also looking to secure contracts with additional module manufacturers. “Our technology’s been ‘de-risked,’ it’s passed all the testing, now it’s all about the commercial ramp,” he added.

Potential Pitfalls & Roadblocks

What potential hurdles and roadblocks does ArrayPower management foresee and plan for as its works to ride the growing wave of solar power installations and market expansion?

Both Arienzo and Cravalho noted that although the leveled cost of electricity produced by solar power systems is coming down the cost curve quickly, the elimination of government support and incentives could threaten the industry’s ongoing development and maturation.

“Long-term, the future for solar is very bright; the industry is weaning itself off subsidies,” Cravalho said, “but that’s still a few years away. If those subsidies dry up it would threaten the industry’s growth and development in Europe and the US.”

Arienzo’s first experience in the solar industry dates back 25 years, when she had a job casting silicon ingots in Italy. She’s returned to the solar industry having spent the ensuing years involved with semiconductor manufacturing for companies such as IBM and Philips.

Arienzo experienced first-hand solar’s first attempted emergence into the power industry mainstream. That was in the early seventies, when Jimmy Carter was president and the OPEC oil embargo caused a global oil shortage and price shock. The effects finally wore off a decade later as oil prices fell and stayed low, though never to the levels seen before the embargo. “Having lived through this once before with Carter, I don’t want to go through it again,” she said.

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