" So, if you have the extra space, that's probably the most cost
effective way"

CPV supporters constantly repeat the claim that it will produce more
power per acre than flat panels.
This claim has not been proven.
Tracking arrays require adequate spacing to prevent shadowing.
First Solar uses very low cost cadmium telluride panels and it is only
about 10% efficient.
Those panels will not be made available to the public because they do
contain some hazardous materials and must be returned to the
manufacturers for recycling at the end of their working life.
Even so it is ideal for building large solar farms in which the land
cost is only a very small part of the equation.

Here is a Silicon flat panel company with a simple non shadowing
tracker (look at page 2)
http://www.sunpowercorp.com/Products-and-Services/~/media/Downloads/for_products\
_services/spwr_t20tracker_en_lt_w_ra.ashx

These products are going into large solar farms right now.

CPV????