Serious about solar

by Tyler Shendruk

Published: 12/8/10

The problem
OIL IS EVIL. Humanity go green now. Solar panels suck. Apocalypse therefore inevitable.

The researcher
Karin Hinzer is the Canada Research Chair in Photonic Nanostructures and Integrated Devices. In 2007, Hinzer founded SunLab at the University of Ottawa, and since then has collaborated with many industrial partners. Just this year, a collaborative effort earned SunLab the 2010 Canadian Innovation Award.

The project
One such joint project is the Advancing Photovoltaics for Economical Concentrator Systems (APECS). APECS is a project that demonstrates the use of innovative technology in a practical setting. In January, Hinzer will install experimental solar panels on the roof of the Sports Complex parkade here at the University of Ottawa and at a sister site in northern California.

The key
Hinzer will use efficient gallium/arsenide(Ga/As) based multi-junction solar cells in the APECS project. Traditional silicon solar cells only absorb a small range of photons efficiently, while multi-junction cells absorb over a broader spectrum and so increase the efficiency. However, these solar cells are not cheap. APECS seeks to bring the cost down in a couple of ways.
First, Ga/As cells are usually grown on expensive germanium sheets, but Hinzer is testing Ga/As cells grown on much cheaper silicon sheets. Secondly, Hinzer is reducing the cost by getting more light to a smaller area. The way Hinzer does this is analogous to a kid using a magnifying glass to turn a normal sunbeam into a highly focused death ray for burning ants. But instead of using normal lenses, Hinzer uses waveguides that have been tested in SunLab under an artificial sun. Since the waveguides are much lighter than traditional lens systems, it won’t need the same kind of heavy-duty foundation that other big solar panels require. Therefore, it can be set on rooftops.
But having an efficient solar cell is only half the battle. If there’s only a little light shining on the solar panels, they won’t produce much electricity, no matter how efficient they are. To get around this, the modules will automatically track the motion of the sun to maximize their efficiency throughout the day. Solar panels work best when the sun’s rays are perpendicular to their surface. This is why APECS will have one station here in Ontario and a second one in California. Each panel will have an associated weather station, which Hinzer will use to compare any differences in efficiency to differences in latitude and weather.