For renewable power to reach complete penetration into mainstream markets, all the relevant players, including customers, government agencies, private industry and utilities must fully participate.

When it comes to solar power, much recent growth has been driven by small-scale, customer-owned systems. However, change may be underway. Perhaps indicating that the market for solar power has reached its proverbial tipping point, utilities now also appear to be getting into the act.

According to a recent study released by the Solar Electric Power Association (SEPA), utilities are adapting to solar as their fastest growing electricity source. SEPA’s fifth annual Utility Solar Rankings analyzes the amount of new solar power interconnected by U.S. electric utilities in 2011.

The first measure shows utilities interconnected more than 62,500 photovoltaic (PV) systems. In contrast, the survey notes that only 350 nonsolar power plants were expected to be interconnected across the country last year. Granted, most of these PV systems have a much smaller generating capacity than your typical plant, but a trend is clearly underway. The survey notes the number of installations grew by 38 percent from the year before. Furthermore, forecasts call for the number of integrations to reach 150,000 by 2015. More than a dozen utilities connected more than 1,000 PV systems last year, and many others connected 500 or more.

As the number of interconnections grew, so did the amount of power the systems are capable of generating. Collectively, SEPA noted that the most “solar active” utilities accounted for a total of almost 1,500 megawatts (MW) of new integrated solar power last year. Individually, many reported integrating 20 MW and even 50 MW of new solar power.

Not surprisingly, in comparing the two measures, the survey found that residential solar drove the first, while commercial systems played a greater role in the second. Smaller, residential rooftop solar represented 89 percent of the new PV systems installed last year. On the other hand, larger, commercial systems represented 53 percent of the new generating capacity. SEPA also noted that the growth in capacity from solar in 2011 is a 120 percent increase from the year before.

Finally, utilities themselves are also embracing solar power. According to the survey, solar power procured by utilities represented 39 percent of the total growth in capacity, compared with only 9 percent three years before. This consists of wholesale power purchased by utilities as well as utility-owned projects. Both of these are in contrast to the typical customer-driven, small-scale residential and commercial projects.