I use this one at home in the summer. It seems to work best (for me) with the additional reflector attached and in the middle of the day when the sun is highest. In seasons when the sun doesn't get very high, and in summer after the sun is lower (3:30 or so), I just don't get the results I would like.
I tend to use it on really hot summer days when I want to bake something, but don't want to heat up the house. Baking inside on those days when it's 112 outside overloads the AC so badly we can't sleep at night. Those are the times the thing is really useful.
All that being said, I am not sure how well it would do in PNW with fog, cooler clime, etc. I imagine it would do o.k. in DV in spring and fall (in summer, it wood cook quickly and you'd have to worry about it melting). It surely would benefit energy consumption during extended boondocking, but it would also take up precious space.
http://www.solarovens.org/
Dave F, if you are really interested, we might be willing to sell ours. We're in Sacramento.