Can you see the display at night? My husband works at night- outside.

The display is illuminated brightly for a few seconds when the light button is pressed, and is easy to read (especially with the large display). You can also set the display to light up when any button is pressed.

Is it solar powered or uses battery?

Takes CR2025 3V battery. It is stamped on the back. Changing is easy. Use #0 phillips or smaller. Remove 4 screes on back plate. You can get backplate off without removing band, but it is easier if you take one side off by compressing the spring pin. There is another screw holding the battery in.

My eyesight is poor. Is there a digital watch to suit me

The characters appears in black on a grey/silver background. The hours and minutes are in approximately 64 point font and the other functions/reporting is in approximately 24 point font. At 70, having worn corrective lens since age 6, I find all of the characters on this watch easy to read.