1366 Technologies, a company named after the solar constant (there are 1366 watts of solar radiation hitting each square meter of the Earth on average) is working on improving multi-crystalline silicon solar panels. They claim to have found ways to make them about as efficient as single-crystal silicon solar cells, which are more efficient but also more expensive, without losing the cost benefits.
Three different innovations (described below) allowed them to make their prototype 27% more efficient than conventional multi-crystalline silicon solar cells, bringing its total efficiency to 19.5%, about the same as single-crystal silicon solar cells.Here's the first innovation:
[...] adding texture to the surface of the cells that allows the silicon to absorb more light, a trick that's been used before with single-crystalline devices but has been difficult to implement with multicrystalline silicon.
The goal is to bend the light slightly so that it doesn't bounce out of the cell but rather is reflected and bounces back in, giving it a higher chance of being absorbed and converted into electricity.
The second innovation:
[...] silver wires harvest electrical current generated by the silicon. Sachs has developed a method for making these wires as small as one-fifth the width of the wires that are typically used, while improving their conductivity.
Less silver equals lower costs, Thinner wires means less light blocked.
(see also the first image in this post)
The third innovation (and the most interesting, in our opinion):
a set of wide, flat wires used to collect current from the thin silver wires. These bars typically block light entering the cell, reducing efficiency. But Sachs has etched their surfaces so that they act as faceted mirrors.
So some of the light that would be lost is bounce back into the cell, bringing efficiency higher.
1366 Technologies plans to make its own cell - they just raised $12.4 million and are planning to build a 25 megawatt plant if all goes well - but they are also open to licensing their technology to other solar panel makers. The company expects solar cells produced on a large scale to compete directly with coal at about $1/watt generated by 2012.
See also: ::19.9%: New Thin Film Solar Efficiency Record, ::Solaria: Finding Clever Ways to Make Cheaper Solar Panels, ::Ausra: Solar Power Around the Clock, Enough for 90% of U.S. Grid, ::Torresol to Build 3 Solar Thermal Power Plants in Spain for $1.24 Billion
Update: If you are interested in solar power, also check out 15 Photovoltaics Solar Power Innovations You Must See.