absolutely. this is what is known as an array heliostat, and most used to generate steam are 12 feet square and use 6 inch mirrors. from what i ubderstand, it is possible to create enough steam to run a 5+ kw generator.
as i am living in nevada, this is the one way to create my own power that i am seriously looking at (it's cheaper than PV anyway).
from the site:
The Solar Death Ray is made of 112 mirrors mounted on a platform 4 feet
wide and 6 feet tall. Each mirror is a square roughly 3.5 inches on edge. All
these mirrors focus the sun to a single spot 5 feet, 6 inches from the mirror
platform.
Using some basic principles of Black Body Radiation, I estimate that the
Solar Death Ray can heat things up to between 500-600 degrees Celsius
(930-1100 degrees Fahrenheit) under good conditions. This assumes that
heat is not lost due to conduction and convection of the air around the
target, which is unlikely.