A state commission has approved a 50 percent increase in the wholesale electricity price cap in a move it hopes will spur construction of more power plants.

The Texas Public Utility Commission voted Thursday to raise the cap on Aug. 1.

And this could be just the start. Commissioners are considering, but aren’t yet expected to vote on, tripling the wholesale price starting in summer of 2013.

Officials say the state must boost generating capacity to meet growing demand and avoid rolling blackouts during peak periods like hot summer days. But industry and consumer groups warn it could raise costs by billions of dollars that could eventually mean higher electric bills for Texas households. And they say there’s no guarantee the higher rates will result in new construction.