Green Patent Blog

A recently-published patent application filed by Apple Computer (Apple) is making a splash and fueling speculation that the computer and electronics giant will soon be launching solar-powered mobile devices, including a sunny version of the super-trendy iPhone. 

U.S. Patent Application Pub. No. 2008/0094025 (’025 application) published in late April and is entitled “Solar Cells on Portable Devices.”  The ‘025 application is directed to processing systems coupled with solar cells and methods for connecting solar cells to portable devices. 

The basic idea of connecting solar cells to portable devices is probably obvious in both the colloquial and patent law sense (non-obviousness is one of the main criteria for patentability, and a combination of known elements must be non-obvious to be patentable).  With the ‘025 application, Apple seems to be betting that its solution for maintaining a consistent voltage and sufficient power output with a small number of solar cells, even when some of the cells are obstructed (e.g., because of a user holding the device), is worthy of patent protection.

The ‘025 application describes a way to arrange solar cells so that some cells will continue to function while others are blocked from sunlight.  The system involves networks of cells connected both in series (end to end so the current flows in a single path) and in parallel (the current flows through each component, providing the same voltage across all components).

In one example disclosed by the ‘025 application, two individual solar cells of a first type (”A1″ and “A2″) are connected in parallel, and two individual solar cells of a second type (”B1″ and “B2″) are connected in parallel.  These two pairs of cells are then connected to each other in series (i.e., A1/A2 is connected to B1/B2).  The pairs are arranged in an alternating checkerboard pattern so A1 is diagonally opposite A2 and B1 is diagonally opposite B2.  According to the patent application, this arrangement provides more consistent power output in the event of obstruction of sunlight.

No word yet on whether Apple will be launching its solar electronics, when it will do so, or which products will be getting the solar treatment.  But this is a patent application everyone will be watching.

British Columbia based Xantrex Technology (Xantrex) makes advanced power electronic products that convert electrical power into other forms of energy.  One of Xantrex’s major markets is renewable energy, and the company is a world leader in production of solar inverters (pictured below).  Solar inverters convert DC power captured by solar panels into AC electrical energy.  The energy is then provided directly to customers or to a utility or electrical grid.

In November 2007, Xantrex sued Advanced Energy Industries (AE) and Christopher S. Thompson in federal court in Colorado, alleging, among other things, breach of Thompson’s employment agreement (against Thompson), misappropriation of trade secrets under Colorado law (against Thompson), breach of fiduciary duty and aiding and abetting such breach (against Thompson and AE, respectively), tortious interference with contract (against AE) and violation of the federal Computer Fraud & Abuse Act (against Thompson and AE). 

Last month Judge Wiley Y. Daniel denied the defendants’ motion to dismiss (based on a forum selection clause in Thompson’s employment agreement) and granted Xantrex’s motion for a preliminary injunction (PI), ordering that Thompson could not work for AE as Vice President and General Manager of Solar Inverters (or work on solar inverter technology for any other North American competitor of Xantrex) for a period of one year (xantrexorder.pdf).  Thompson and AE were also ordered not to use or disclose any Xantrex trade secrets.

Xantrex’s complaint (xantrex.pdf) alleged that Thompson breached his employment agreement by leaving Xantrex and immediately starting employment with AE (the non-compete provision prohibited Thompson from working for any competitor within one year of leaving Xantrex).  Thompson worked on solar inverter technology at Xantrex, and AE entered the solar inverter market shortly before Thompson joined AE. 

While at Xantrex, Thompson was Vice President of Engineering and Product Development and had access to the company’s confidential information.  According to the complaint, Thompson had played a leading role in acquiring and integrating certain cutting edge solar inverter technology into Xantrex’s products. 

The complaint also alleged assorted shenanigans by Thompson shortly before he left Xantrex, including downloading and transferring confidential Xantrex documents from his laptop, attempting to delete files to cover his tracks, and using Xantrex’s confidential market data to create market plans for AE.

Judge Daniel found the PI factors (likelihood of success on the merits, irreparable harm to Xantrex, threatened injury to Xantrex greater than harm of a PI to AE, and effect of PI on public interest) weighed in favor of granting the PI.  The irreparable harm is that AE would get a head start into the solar inverter market based on Xantrex work, money and trade secrets if Thompson were permitted to take a position at AE nearly identical to the one he had at Xantrex.

As to success on the merits of the trade secrets claim, Judge Daniel found enough evidence that the confidential information accessed by Thompson prior to leaving Xantrex rises to the level of trade secrets (e.g., solar inverter product development information and data on the benefits of various product features).  The court also found that Thompson’s rapid accessing of trade secret documents just before leaving Xantrex was of particular concern because his ready recollection of possible trade secrets would make their use by AE possible without him actually telling anyone.  In other words, Thompson’s mere knowledge of the information would make misappropriation likely.

The court also found Xantrex would be likely to succeed on the breach of contract claim.  Interestingly, Judge Daniel analyzed the non-compete provision under Canadian law, which strongly disfavors such restrictive covenants.  The court therefore took a “blue pencil” approach and modified the clause so the geographic restriction, which was global in scope, only covered North America.  With this modification, Judge Daniel found the breach of contract claim likely to succeed under British Columbia law. 

Australian solar cell company Dyesol has developed transparent dye-infused solar cells that can be sandwiched between two panes of glass to transform windows into energy collection devices.  In a process based on how plants generate energy, Dyesol’s cells use a dye analogous to chlorophyll to absorb light and generate electrical energy.  The cell consists of a nano-particulate porous film formed on a conductive substrate, a layer of dye, a transparent conductor and an electrolyte placed between the dye and the substrate.  The dye-coated nano-particles increase the surface area available for light absorption.  (read more about the technology on Ecogeek and Inhabitat)

Dyesol owns a patent application directed to its proprietary method of manufacturing the dye solar cells.  U.S. Application No. 2008/0105362, which published last week, claims a manufacturing method that comprises forming a nano-particulate layer on a conductive substrate, applying a dye to the nano-particulate layer and treating the nano-particulate layer with an electrolyte.

The resulting dye solar cells differ from traditional solar cells in how light is absorbed and how charge carriers are generated.  In ordinary photovoltaic cells, sunlight is absorbed by a semiconductor material such as silicon, which knocks electrons loose from their atoms, creating electricity.  Here, the dye chemically absorbs the sunlight and generates electrons to carry charge through the conductive substrate.  Thus, instead of photovoltaic or photoelectrical (light to electricity) cells, by virture of the added dye, these are photoelectrochemical cells.

For solar power to be truly competitive with traditional energy sources, it has to approach cost parity with power generation using traditional sources. The two primary ways to do this are to increase the efficiency of converting sunlight to power (the approach most in the industry have taken) and to lower the manufacturing cost of solar cells. Nanosolar has focused on the latter, and has at least three patents that cover its manufacturing technique. According to this New York Times article, Nanosolar can profitably sell solar panels for less than $1 a watt, the price at which solar energy becomes cheaper than coal.

Solar cells typically are made by manufacturing methods borrowed from the semiconductor industry that consist of depositing photovoltaic film on silicon wafers. Nanosolar instead uses a printing technique to lay thin film photovoltaic material on a conductive metal foil. This method is possible because Nanosolar’s thin film solar cells are made of copper indium gallium selenide (CIGS) instead of silicon, which provides additional savings by giving Nanosolar immunity from silicon supply shortages and fluctuations in the price of the silicon raw material. Silicon solar cells are made from slices of solid silicon instead of the metal foil used by Nanosolar to make CIGS cells.

At the particle level, Nanosolar’s solar cells have a different structure from traditional silicon solar cells. In silicon cells, the absorption of photons of light results in the formation of a free electron and hole (the space remaining when an electron moves). In the Nanosolar cells, the photoexcitation leads to formation of a bound electron and hole pair called an exciton. To optimally convert light to electrical energy, the electron and hole comprising the exciton have to be spaced a certain distance from each other so that charges can be collected at different electrodes.

U.S. Patent No. 7,253,017 describes Nanosolar’s manufacturing process and claims a method of fabricating thin film solar cells having electron and hole-accepting materials at the right distance for optimal exciton activity. A film having a network of interconnecting nanoscale pores is formed on a substrate. Then semiconducting materials are deposited in the pores. After the pores in the template film have been filled, the template is removed using a chemical process that leaves the semiconducting material intact as a nanoscale grid network. The remaining spaces between the nanoscale grid network are filled with a complementary semiconducting material so the resulting interfaces have ideal conditions for electron travel and charge collection.