It’s no giant leap forward, but the efficiency of solar cells just took a step forward. According to Renewable Energy Access, researchers at the University of Delaware have built solar cells that convert 42.8% of the energy that hits them into electricity, a new record. Conventional photovoltaic (PV) cells like those popping up on houses around the country tend to be 15%-20% efficient. To deliver the same juice as a batch of today’s PV panels, this new recipe would need less than half the surface area. Don’t expect to see these very high-efficiency cells at Lowes anytime soon though. High output cells tend to be very costly, so are limited to niche uses where space, weight and efficiency are bigger worries than price: so satellites and and self-powered systems that monitor remote infrastructure (oil pipelines, or telecoms repeating towers) are the first to use them. Later, as manufacturing processes improve, higher efficiency designs trickle down to the mass market. In this case, DuPont plans to work on commercial prototypes, available as early as 2010.