University of Rochester researchers have been awarded $1.5 million to develop a technology that could reduce the cost of electricity from solar power. The technology would replace the area that needs to be covered with expensive solar panels with less expensive, plastic solar concentrators and fewer solar cells.
The Rochester project is one of 11 solar power projects that are part of the initiatives announced by President Barack Obama last week to drive innovation and accelerate a clean energy economy. The solar power projects aim to lower the cost and improve the performance of solar photovoltaic power systems. The projects are funded by the Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E). In the announcement, ARPA-E stated that they expect these initiatives will spur innovation, ensure grid reliability and help ensure America's low-carbon energy future.
The Rochester team, led by Professor Duncan Moore and Research Engineer Greg Schmidt, will be developing a planar light guide using micro-optics to capture, orient, and concentrate direct sunlight onto a single photovoltaic (PV) cell. Using less expensive plastics, their light guide will concentrate sunlight so that fewer expensive PV cells will be needed.
"The most efficient PV cells are very expensive, up to $50,000 per square meter," said Moore. "If we could concentrate the sunlight 500 times, we'd need fewer of these cells as the solar concentrator would cover the bulk of the area. This would mean the cost would be $100 per square meter."
The team's system will be very thin (less than 3 mm thick) and lighter than similar, existing panels. This will also help reduce the cost, as it will be easier to move the whole system to face direct sunlight.
Moore, vice provost for entrepreneurship and a professor of optical engineering at Rochester, said that his team already has an early prototype that demonstrates the potential of the technology. "With this grant we will be aiming to produce the next generation solar concentrator, one that will be cheaper to make and can be produced at a larger scale."
The team has already identified a potential commercial use. "One advantage of using our approach is that our planar light guide is translucent, so any light that is not concentrated into the PV cell will go through the material," said Moore. "This is of interest to architects as it provides a material that will be letting light through at the same time as helping produce electricity from solar energy."
The team holds five patents for their unique approach to solar concentrators. Moore explains that their technology can be thought of as being a bit like using a magnifying glass to focus sunlight to burn a hole in a piece of paper. However, the Rochester system is much more compact and efficient. The group produces an array of very small plastic lenses, each about the size of a pen tip, on the surface of the material. These focus the light a certain depth below the surface of the material, where there are air "bubbles" of a specific shape. These act like prisms, guiding the light along the material to the edge. The PV cells only need to be placed along one edge of the material, where the light guide formed by the tiny air prisms concentrates the sunlight.
With the support of the grant Moore' team will be working with three partner companies - RPC Photonics (Rochester), ORAFOL (Rochester) and ARZON (San Diego, CA) - to develop these designs to be commercially viable.
The ARPA-E supported projects, collectively known as Micro-scale Optimized Solar-cell Arrays with Integrated Concentration (MOSAIC), seek to develop new solar technologies that will create highly efficient photovoltaic (PV) panels that capture more sunlight using less area. For example, many roofs are not well suited for conventional solar panels due to their size and/or location, making it inefficient and costly for some residents, businesses and utilities to use solar power. However, using CPV optical devices that concentrate sunlight onto a smaller, high efficiency solar PV receivers can reduce the quantity of expensive solar panels needed, while maintaining their ability to generate electricity. The funded projects will try to make these solar concentrators more affordable and usable.