The Solar Energy Industries Association (SEIA) issued a warning concerning the growing number of rooftop solar installations, noting that soon, US utilities could potentially refuse to buy power generated from the systems. Rhone Resch, CEO of SEIA, acknowledge that although utilities are required to purchase electricity generated by solar panels installed on consumers’ homes under net-metering policies, the arrangement may become less practical as solar systems become more common.

“Net metering works for us now, but we’re going to see a backlash from utilities as solar penetration increases over the next few years,” Resch said in an interview with BusinessWeek at Solar Power International this week.

Resch pointed to California, the largest solar market, which also capped the amount of panels utilities are required to connect to their grids at 5% of a utility’s s power needs. Other states may soon follow suit as, Resch states, utilities are seeing the requirement to buy solar power from every rooftop system as a threat to their profitability. Further, Tom Clifford, CEO of Standard Solar, advised that California utilities are looking into the long-term impact on their profits, with, again, other states expected to follow.

“I’m really concerned about a utility pushback on net- metering,” Clifford said in an interview. “What we need is an honest assessment of the true costs and benefits of managing distributed generation and I don’t think we’ve seen that yet.”

As of now, utilities are considering ways to offset the cost of buying solar, including Sempra Energy’s San Diego Gas & Electric. The organization recently proposed imposing a fee for residential solar customers, which regulars blocked in January. “That would have made almost every installation lose money and prevent new projects from getting financing,” commented Aaron Hall, president of Borrego Solar Systems.