Solar Roof Panels
Crystalline silicon wafers have many drawbacks. They’re expensive. They’re usually encased in glass, which makes them heavy and brittle. Their manufacture is dependent on fossil fuels and results in pollution and waste. In spite of this, they dominate the PV cell market. Because crystalline cells are connected in series, if one breaks, is shaded or isn’t connected properly, the array is dysfunctional. Although technically they are more efficient than other kinds of photovoltaic cells, they often don’t perform as well because of the high temperatures on rooftops which reduce their efficiency. Enter amorphous photovoltaic cells made by Energy Conversion Devices or ECD.
In the late 1990’s, a subsidiary of ECD — Uni-Solar — revealed a new class of PV cells. Triple Junction PV modules are named for the three layers of PV junctions that are stacked atop one another, with each layer attuned to a different wave length of light i.e blue, yellow/green and red. Compared to old-style glass type panels, Triple Junction PV modules are 30% more powerful and are much more effective in high temperature applications. Because they are coated with Dupont Tefzel glaze, they are able to withstand golf ball-sized hail and similar impacts. An installation funded by the Department of Energy in Hawaii in 1998 is still holding up and working well.
Perhaps the most surprising and promising facet of the Triple Junction line is that it can be used for roofing, just like normal shingles, and even looks like conventional shingles. Because, unlike glass encased PV panels, there is no need for an aluminum frame, it takes far less time to install Triple Junction PV modules. The flexible panels are laminated to metal roofing, on site, and in some instances are actually less expensive than composite shingles. According to Stan Ovshinsky, the inventor of amorphous PV cells and ECD’s founder and former CEO, “production costs are well below any other PV product. Our problem is keeping up with demand.” (http://www.renewable-energy-world.com) Because of these lower production costs, Triple Junction PV modules have the fastest energy payback — the time it takes to recover the costs of making them — of any PV cell.
When compared to fossil fuels or nuclear power, the ECD product is miles ahead in terms of efficiency and even cost, when factors like pollution, land area to return and transportation costs are taken into consideration. Coal for instance, involves mining land and the disposal of waste which covers vast areas in some places in the US and other countries. Nuclear power is dangerous, subject to terrorist threats and has an unsolved problem with waste disposal. Nuclear power also depends heavily on government subsidies, a hidden but real cost.
ECD is the biggest player in the amorphous film PV cell industry, as well as a key manufacturer of other renewable energy technology. The Ovshinskys, Stan and his late wife, Iris, his working partner for more than fifty years, concentrated their research in two areas: information and energy, which Stan called the “twin pillars of the global economy.” Their subsidiary, Ovonics Universal Memory, is involved in multi-level technology, phase-change research and innovative approaches to memory storage and artificial intelligence. In addition to amorphous PV cell modules and IT technology, ECD and its subsidiaries produce NiMH batteries, hydrogen-based vehicles, hydrogen storage systems and fuel cells.
The Ovshinskys have received many awards including the Popular Science Grand Award. They have been featured in two PBS documentaries and honored by the American Chemical Society for “significant and lasting contributions to global human welfare with their invention of environmentally sustainable energy generation and energy storage applications.” Their IT work funds their PV cell research, which gives them much more latitude in research than companies with a single-technology approach to PV cell manufacture. Add to that their many other lines of hydrogen-based technologies and it’s clear that amorphous PV cell research will be fully supported at ECD far into the future. In 2001, the Forum of Chalcogeniders established the Stanford Ovshinsky Award for Excellence in Non-Crystalline Chalcogenides to honor his pioneering work and recognize the contributions of scientists and technologists in this field. (http://www.ovonic.com)
Tags: power, roof, solar, solar cells
