As U.S. policymakers debate the best renewable policy for the country, many German experts are already convinced they know the answer: a feed-in tariff. Germany’s feed-in tariff, which offers generous set prices for renewable electricity fed into the grid, stimulated 1.5 gigawatts of new solar capacity last year, and similar programs also have boosted markets in countries such as Spain, Greece, Italy, Turkey and South Korea. All the fastest-growing solar markets in the world today have feed-in