"The company has done a number of installations... including a housing project in Rhode Island last year... The payback was just over five years..." This means

"The company has done a number of installations... including a housing project in Rhode Island last year... The payback was just over five years..." This means, of course, that the expected payback is five years. Who knows how good the installation job was, and how generous the assumptions made when estimating the payback period.