Printing Solar Panels

By Kurt Cagle
January 15, 2009 | Comments: 9

Solar power represents in many ways the purest form of energy available to our energy hungry culture. The sun's energy is endlessly renewable (well, for at least the next three billion years or so, at which point, we'll likely have too much of it), produces no greenhouse gases, and is available nearly anywhere.

The problem, of course, is that while the energy is there for the taking, converting that energy into a usable, transmissible form is a considerably more complex undertaking. Solar panels (properly, solar photovoltaic cells) traditionally have been expensive to create, require a fairly significant amount of area to generate meaningful energy and are usually fairly fragile. What's more, most contemporary (second generation) solar technologies tend to be relatively inefficient, converting only between 5% to 10% of the energy directed to them. As a consequence, solar's role has long been relegated to that of secondary power producers, ideal for providing power for an individual house but insufficient for larger uses.

A number of recent advancements in solar voltaics is changing this perception, however. Third generation photovoltaics use several differing techniques that seek to lower both cost and raise efficiency, with a goal towards exceeding the 30% efficiency limits that represent the upper edge of what's possible with second generation technology. One of the more intriguing of these is a novel use for inkjet printers.

In Germany, a partnership of two companies - solar cell manufacturer Roth & Rau AG and inkjet manufacturer Innovalight (or Sunnyvale, California, appropriately) is creating a new generation of silicon based solar cells that are quite literally printed - Innovalight has created a new generation of inkjet printer that sprays specially constituted silicon ink onto a thin plastic substrate, which are then incorporated into solar panels manufactured by Roth & Rau.

This process significantly lowers the overall cost of production of these panels, and because the printed layers of silicon can be made considerably thinner than corresponding first and second generation silicon, the process is able to convert more of the incoming sunlight into energy rather than have it get dissipated as heat.

The first pilot platform, installed at Innovalight, is capable of generating 10 megawatts of power, and the system could readily be scaled upward to generate potentially hundreds of megawatts in a full generator environment, enough to meet the power requirements of a smallish city.

While the use of silicon ink in this respect represents something of a breakthrough, thin film silicon voltaics are definitely becoming a growth industry. In December 2008, First Solar, of Tempe, Arizona, created its own 10 MW plant for use by Sempre Generation in Arizona, and more recently has won a contract to supply additional modules to Masdar City in Abu Dhabi.

High efficiency solar voltaics likely represent a turning point for the technology. Taking up only about 20% of the total area of older generation photovoltaics for the same power generation (and costing far less per MW generated), most contemporary solar installations also include advanced computer intelligence to better manage solar tracking and power generation and are taking advantage of high storage batteries and super-capacitors to store the power produced during the day and even out the power distribution load at night.

What this means in practice is that such solar installations are being increasingly seen as a viable alternative to traditional big power generation not just in high sun areas but even in cloudy regions such as Northern Europe or the Pacific Northwest. Moreover, these installations are more effective in building distributed power grids than large scale (and high cost) natural gas, coal or hydroelectric generators, with fewer of the environmental costs than any of these.

Kurt Cagle is online editor of O'Reilly Media. Feel free to subscribe to his newsfeed, or follow him on Twitter.