Businesses often look for a two- to three-year payback on capital investments. Solar power cannot yet provide that; the average commercial installation is expected to pay for itself in five to nine years. Mr. Subacus said that Janssen's would take 20 years to pay for itself, much longer than average, because he is assuming that energy prices will rise only 4 percent annually; if they climb faster, the system will pay for itself sooner.
Solar power accounts for only three-hundredths of 1 percent of all electricity generated globally, said Lisa Frantzis, director of renewable and distributed energy at Navigant Consulting in Chicago. Yet sales of equipment are growing quickly. Since the 1990's, the market for products that capture electricity from the sun has grown about 20 percent a year, In the last three years [in the US], the growth has accelerated to about 33 percent a year.
Even though solar power is on a growth curve in the United States, the technology is spreading even faster in Japan and Germany. In Japan, higher prices for other types of energy have bolstered the popularity of solar power. There are fewer than 5,000 grid-connected solar setups in the United States, compared with 40,000 systems in Japan, most of them residential, said Glenn Hamer, executive director of the Solar Energy Industries Association in Washington.
Other countries are also quickly developing uses for solar technology, Ms. Frantzis said. In 1999, the United States accounted for 17 percent of the global solar market. Last year, it accounted for only 13 percent.
