I'd love to use a solar cooker, but I don't have enough direct sunlight.  I live in an apartment, and my balcony gets only a couple of hours of sunlight a day.
Put it on the roof of your building or building where you work?  Unless someone would steal it.

They are really portable.  I know people who take these on camping trips.

I don't have access to the roof.  I've never had access to the roof of any building I've lived or worked in.  Liability concerns, I suspect.
The couple who loaned us our first solar oven (we now have two, solar oven society and solar oven), would set their oven out in the morning when they were leaving for work. They would point it due south. When they came home it was cooked to perfection and still perfectly warm, ready for dinner.

We do it that way if we're going to be out all day.

Another option is the Sierra twig stove, by ZZ manufacturing. A single, rechargable AA battery powers a fan, which burns a few handfulls of twigs very hot, cooking our food or boiling our water very fast. We've phased out our propane and only use the twig stove and the solar ovens.

Jim;
  Are you using the Solar oven like a CrockPot, too?  I've been chewing on getting a Solar CrockPot Design to work this way.  Shouldn't be too hard.. and the great thing with crock pots is, as you said, you do all the setup in the morning, and when you get home, a hot dinner is waiting for you.  Soups, stews, potroasts!!

Bob Fiske

I guess.... but maybe it's more like just a slow oven. Slow cooking keeps in the vitamins and taste. Also, one huge advantage of solar ovens is that it cooks in its own moisture. In a conventional oven, the food is surrounded by exhaust gasses from the gas combustion; in a solar oven, the original air is trapped, and becomes very moist. You don't need as much water, it is less likely to stick, and the heating is even so it is far less likely to stick to the pot, or to burn on. Omelletes work pretty well!