I did it myself, it's about 10MW continuous assuming there are 40 ships each taking about 3000 seconds to traverse the locks. Each lock is ~30x330x10 cubic meters or 1Billion liters (conservatively).
A Watt is 1 meter(lift) x 1 Newton / second.
There are 30 meters of lift. Each liter is 1kg and gravity (9.8m/sec2) makes that about ~10 Newtons (9.8N due to gravity).
So you get 10^9kg x 10N/kg x 30m / 3000 sec = 100MW continuous. That's about 100, 000 horsepower. Each lock would need more than 16MW of pumping.
Solar/hydro power from the rain in lake Gatun is well over 100MW. Due to leakage it's probably 5-10x that or equivalent to a larger nuclear power plant.
