The Scottish outfit conceded three tries as the Premiership club earned a 22-12 victory in the capital to leapfrog their opponents in Pool 6.
"It wasn't our best performance and we lacked sharpness and urgency," Solomons told reporters.
"We made mistakes for the three tries they scored and then, when they had a man sin-binned, we had a chance to score but didn't take it.
"That was the pivotal point in the game that could have changed the entire complexion of the match."
Gloucester are now second in the group, while Edinburgh sit bottom.