Concentrating solar power is a well-known approach to lowering the cost of solar electricity. You focus sunlight from a large area onto a small one, the same way a magnifying glass can set a piece of newspaper on fire, using one small, high-quality solar cell and a concentrator for a lower total cost than hundreds of slightly cheaper cells. (Or you can use the concentrated heat to drive a heat engine, but not in the example we are about to discuss.)
Morgan Solar has a smart variation on this under development. They start with a clever acrylic concentrator that uses pure optical guiding to concentrate solar energy about 50 times, around the same results as a Fresnel lens, but without the need for curves or a non-zero focus. This already moderately concentrated solar is then concentrated further by a much smaller glass concentrator that also needs no air gap. Because neither concentrator requires an air gap, a tiny solar cell is attached directly to the glass.
So you have an eight-inch acrylic concentrator, a glass concentrator the size of an American nickel, and a solar cell the size of a baby's thumbnail.
