As we know, we can instal one mirror, get one sun reflected to the spot we want to illuminate, or two or more mirrors aimed to that same spot for greater illumination intensity, or two or more mirrors for an expanded area.
Going to a parabolic mirror, the target spot gets smaller, concentrating much more light on the same spot. It may become uncomfortably bright.
Heliostats means keeping the target illuminated while the sun travels on the sky. If that is the objective, well, there is another way; by using a convex or more than one convex mirror to aim somewhat dimmer sunlight or several ĺayers of sunlight one on top of the other or stacked one above the other.
A single convex mirror yields less illumination intensity, but may get rid of tracking mechanisms to a good degree. Several convex mirrors can add to the intensity or to the target area.
So. I will be ordering a 4' x 8´ x 1/4" plastic mirror to play with, like these people do:
Using it single or cutting it to yield two stacked 2' x 8' could be interesting. The curvature to which the mirror be flexed, will define the target bandwidth spread and the sun angle-hours that will work without tracking.
I see it as a cheaper alternative, not much risk of breaking it, unpowered, no failprone mechanism$, no need for post, bearings.
Please let me know your experienced pros and cons of what I will be missing here, like spraying some protective backcoating.
Now, what if by the nobility of plastic, it could be somewhat flexed both
vertically and horizontally, like a section of a bubble face ?
OR : using something like this instead : ---> http://shard3.1stdibs.us.com/archivesD/upload/8880/30/XXX_8880_1269871137_1.jpg
For the purpose of mild, large illuminated area with no tracking ?