from Gizmodo by
Sean Fallon 
Using traditional photovoltaics and a very non-traditional inflatable concentrator and tensegrity truss rigging structure, the folks at Cool Earth Solar have developed a system that could be far cheaper than polished aluminum mirrors. In fact, the inflatable versions are up to 400 times cheaper than regular mirrors and they are so lightweight that they can be suspended on cable lines as opposed to individual base systems —thereby using far less steel in construction. That means faster installation and minimal land use disruption.
Unfortunately, the design does have its drawbacks. For one, the inflatable mirrors would be fragile and less efficient than traditional methods due to the unique shape and the effects of wind on the non-rigid frame. So, in reality, the true cost effectiveness of such a set up is still unknown. Still, Cool Earth hopes to make solar power as cheap as non-renewable power within the next three years. [Cool Earth via Eco-Geek]