SolarHype (Solar Hype) gets practical to deliver real value to solar installations.
Is PowerString the real SolarMagic?
With “National Semiconductor Acquires Act Solar, Extending Its Solar Energy Efficiency and Management Capabilities”, National Semiconductor Corporation (NYSE:NSM) purchased a string based photovoltaic (PV) DC power optimization solution in favor of its overpriced module based product. Per “National Semi Buys Act Solar” by Ucilia Wang in the Green Light blog at Greentech Media, “National Semi declined to say how much it paid for Act Solar. Jenkins said it was an all-cash transaction.”
While the Act Solar Active Power Management Whitepaper describes the problems PowerString (datasheet, product overview) solves, it does not delve into the technology. As I understand it, PowerString senses the main solar array MPP (Maximum Power Point) voltage and monitors the string current to determine whether the string solar modules are generating maximum power. If any string solar modules are impaired or shaded, PowerString uses a Buck Converter arrangement to bias the unimpaired or unshaded modules at their MPP voltage thus recovering secondary and tertiary string power losses. The PowerString bucks the array MPP voltage to match the lower MPP voltage of the power generating modules.
A tale of residential versus Commercial and Utility scale PV
National Semiconductor senior vice president Key Market Segments Mike Polacek said:
Now with Act Solar we can further improve the performance and efficiency of solar systems, at the same time providing monitoring capabilities not available before. This will make solar installations more efficient and ultimately reduces the cost of solar energy for everyone.
Act Solar’s wireless status reporting, diagnostics, and remote Solar Operations Center (SOC) directed towards large scale PV deployments were further icing for the acquisition by National and may have trumped National’s residential focused efforts.
Act Solar has imitators and competitors even if the technology details are different. For example, SatCon Technology Corporation (NASDAQ:SATC) offers the Solstice Subcombiner for String-Level MPPT, DC-to-DC Conversion, and Communications. SolarEdge is developing a holistic, distributed DC solution with an MPPT (MPP Tracking) circuit per solar module and power line communication mating to a simplified, central DC to AC inverter.
Indeed, Act Solar’s ambitions also extend beyond PowerString DC optimization.
When I first pondered how National’s SolarMagic might function, my linear analog skills were fixated on a Boost approach that would step-up the shaded module voltage to the module’s nominal Maximum Power Point voltage. Given the per module architecture, this remains a plausible explanation. The National Semiconductor SolarMagic technology announcement last summer was:
National’s SolarMagic Technology Enables Today’s Solar Technology to Extract Significantly More Energy in Variable Light Conditions; Customer Field Trials Begin
Funny, for a technology announcement, National forgot to discuss the technology!
Two articles, both from Tech-On! by Katsumi Yamashita for Nikkei Business Publications, Inc., in Japan, reveal the most public information to date:
We realized SolarMagic making the most of our analog semiconductor technology. It is in the form of a module, not a standalone IC. The module houses intelligent analog ICs and other technical components. This module is connected with each solar cell module (including multiple solar cells) when used. Accordingly, a system combining three solar cell modules in series and two in parallel requires six SolarMagic modules.
The SolarMagic module is controlled to always operate at MPP in each solar cell module. However, I can’t reveal details of the control technology at the moment. I suppose I can tell them in the first quarter (January to March) of 2009, in which SolarMagic’s volume production and shipments are slated to start.
SolarMagic. This is the first-generation model. Its price is about US$150. “If the production volume increases, the price will naturally drop as a result,” Halla said.
Halla holds the highest hope for SolarMagic among the five products. SolarMagic executes MPP (maximum power point) control in each solar cell to prevent energy output from decreasing when a solar cell module is partially shaded, he said.
Although the unrealistic $150 SolarMagic price per module stated by National Semiconductor CEO Brian Halla might be product life cycle value based or just a list price, I think the photovoltaic market is smart enough to drive this fantasy towards cost plus pricing. Or is a cost reduction to a string based solution already required? Perhaps PowerString will become SolarMagic by another name? There may be a simple answer to all these questions. A chip company just does not have the corporate DNA to market and sell a system solution.
Despite this inaccurate VentureBeat report, “Act Solar awaits $9M to boost energy generation”, Act Solar was planning to ramp PowerString production this Summer for Fall 2009 shipments.
I don’t know if it was like minds, a pun, or flattery with the Chip Shots blog by Tom Cheyney at PV-tech.org using my “Whither OptiSolar” post title sans question mark for a heading in “Solar short takes: Micron explores, Phoenix knows thin film, Barclays’s reforecast, and orbital PV”. All is good though with his new reporting and the original post, “It’s official: Thin-film PV firm OptiSolar to shut down operations, lay off majority of workers”.
OptiSolar is the first well funded thin film start-up to all but fail in 2009. Not my first guess and at least their investors found an exit with the First Solar project pipeline deal.