All generators would be required to verify their capacity under a problem statement approved by the Planning Committee Thursday.

PJM Manual 21 currently requires only combustion turbines and combined cycle generators to adjust their capacity ratings based on temperatures.

Some operators of other types of generation do not adjust their test results for seasonal conditions. In addition, hydroelectric units are permitted to perform their verification tests at any time during the year.

As a result, PJM’s Tom Falin told the committee, some generator ratings may overstate actual output under peak summer conditions.

In response to a question from Frank Francis, director of regulatory affairs for hydroelectric generator Brookfield Energy Marketing, L.P., Falin acknowledged PJM was unaware of any instances in which hydro units had overstated their capacity.

“We’re looking for a holistic solution,” said Steve Herling, PJM vice president of planning.

The problem statement was approved by acclimation. The lone no vote was cast by Francis, who said he opposed the inquiry because PJM has not shown a problem with hydro units.

“This is to see whether a change needs to be made,” responded Herling.