Konarka, of Lowell, Mass. which is one of a number of start-ups racing to develop a way to use plastics for generating solar power, instead of using silicon, has raised another a $20M in venture backing.

This time it comes from 3i Group, and existing investors Draper Fisher Jurvetson, New Enterprise Associates, Good Energies, Vanguard Ventures, Partech International and Chevron Technology Ventures all participated.

Some of these solar companies said their products would be ready this year. Miasole, a local company, said their product would be out last year, but we still haven’t seen it.

Update: More on this in comments below.

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