I'm getting ready to play a hexcrawl/gridcrawl solitaire. I haven't made up my mind to go with a hexagon or square grid map or no grid just abstract little areas.

What's the smallest area have you had your PCs search in?
I like a fairly tight zoomed in area.

I think to many games have you searching to large of an area over a large amount of time.
Like 1 mile or so in 4 hours, that's fine but I'm wanting to get in tight. I want to roll more often to have the chance to find more fantastical oddities.

I'm trying to derive a baseline time to search an area in clear sunny weather in easy going open terrain in an hour With one person. I can go from there to mod that time depending on weather & terrain and more than 1 person, etc. or maybe I should set it up as: 1 person can search a 100 sqft area in 1 hour each.

I'm thinking 100 sqft or 400 sqft

Thoughts/ideas?
Remember this will be solo play.
So I don't have to worry about what will te other PCs do?

a 10x10 area is a decent size campfire location and that be searchable in clear day without any issue is reasonable. 

A good idea is to walk into the biggest room in your house and say "I wonder where I put X in here" see how long it would take you to find X.

10'x10' = 100 sq ft, I would say ten minutes.

It depends, of course.  Let's say you have a 10'x10' area.  If it's flat granite floor with nothing on it, it will take a second to see everything.  If it's a professor's office, it could take hours, especially if you need to read stuff.  Or if you're going to dig up the floor.  Or if you're going to look for secret doors.  Outside is another thing.  If I were to to make a system I'd probably do a 3x3 chart with "cursory," "normal," and "thorough" across the top for type of search and "simple," "normal," and "complex" down the side then fill in the grid with search times, with probably 5 seconds in the upper left box and 8 hours in the lower right.