Green Patent Blog

California startup BioSolar, Inc. (BioSolar) has a different focus than most companies in the solar industry.  Instead of building better ways to absorb the sun’s rays and convert the light into energy, BioSolar develops cheaper and more environmentally-friendly protective backing for solar cells.

Currently, the vast majority of protective backsheets for solar cells are made by DuPont from a petroleum-based film called Tedlar.  BioSolar’s backing is made from bio-based materials.

BioSolar has a patent application directed to a process for building solar cells using a bio-based plastic substrate.  U.S. Application Pub. No. 2007/0295394 (’394 application) seeks to overcome the primary problems associated with bio-based materials in solar applications - their relatively low melting points and de-gasing temperature points.

The keys to the process disclosed in the ‘394 application are de-gasing the substrate material at a temperature of 120 degrees so the material maintains its shape without bubbling or cracking and applying a silicon oxide barrier layer to seal the potential micro-cracks and stabilize the substrate for its journey through the remainder of the solar cell production process.

According to this green tech media piece, BioSolar has not disclosed which bio-materials are used to make the substrate.  BioSolar’s CEO was coy when asked about it, only saying that the substrate layers are made from plant-based materials “not coming from a food source.”

However, the ‘394 application states that the bio-based substrate “is made from Poly Lactic Acid (PLA); a material generated from corn dextrose…”  Last time I checked, corn was a food source.  Perhaps BioSolar is also looking at other raw materials for this promising technology.

Oerlikon is a Swiss company that makes thin-film solar production equipment.  Oerlikon is the worldwide exclusive licensee of “micromorph” tandem cell technology, which it acquired in 2003 from the University of Neuchatel in Switzerland. 

Micromorph tandem cells have two different silicon materials - amorph and microcrystalline - in a top and a bottom cell.  This setup increases efficiency because the amorphous top cell converts the visible light from the sun while the microcrystalline bottom cell absorbs sunlight in the infrared part of the spectrum.

The technology is covered by a family of patents, including European patent EP 0 871 979 (EP patent) and U.S. Patent No. 6,309,906 (U.S. patent), and generally provides a process for making thin-film solar cells using microcrystalline or nanocrystalline silicon.  As discussed in Oerlikon’s U.S. patent, this patent family addresses some of the problems of thin film solar cell production and facilitates large scale production. 

Last month Oerlikon sued German thin-film solar cell maker Sunfilm AG (Sunfilm) in the German District Court of Dusseldorf (pictured above), alleging infringement of the EP patent.* 

One common method of laying microcrystalline silicon on a substrate to make solar cells is called Chemical Vapor Deposition (CVD) and involves using one or more volatile gases, which react or decompose to deposit the desired material.  CVD often results in defects in the silicon layer, including weak photocurrent and negative “doping.”  (doping means intentionally adding impurities to a semiconductor to increase the number of free charge carriers; the level of doping needs to be controlled to achieve efficient solar cells).  According to the U.S. patent, oxygen is one culprit that can cause flaws in the microcrystalline silicon layer.  Oerlikon’s patented technology overcomes these problems by purifying one of the gases before the silicon deposition step to reduce the oxygen content of the deposition gas. 

One interesting point here is that Oerlikon, a production equipment manufacturer, has not sued a direct competitor in Sunfilm, but has instead sued a competitor’s customer (Sunfilm is a thin film solar cell manufacturer, not a production equipment maker) .

Therefore, this lawsuit has raised the question whether Oerlikon also plans to sue Sunfilm’s supplier, California production equipment maker Applied Materials, Inc. (AMAT) (Sunfilm recently awarded AMAT a contract to supply a second line of manufacturing equipment).  Although Oerlikon denies that it intends to sue AMAT for infringement, AMAT knows it may be in the line of fire and has taken a preemptive step in the court of public opinion.  It has issued a statement defending its manufacturing process and asserting that it does not infringe Oerlikon’s patent.

* Unfortunately, I can’t get a copy of the complaint filed by Oerlikon - a German patent attorney informed me that German court papers are only available upon written request and only if one can demonstrate a special interest in the case.  I also can’t get an English translation of the European patent.  Thus, I will limit my discussion to the U.S. patent (which is a sister application of the EP patent and therefore contains a similar or identical description of the technology).

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.