Mounting costs will be lower if panels are mounted on buildings. Although solar panels will never replace oil they will still be useful. There are several ways of using solar energy rather than solar panels. Mirrors focused on panels may reduce cost. In my opinion mirrors focused on solar boilers mounted on or near large buildings are the best way of using solar energy.
Mirrors are cheaper than photo cells.
This gives heat in the winter plus some power. There is enough solar energy in summer to produce a lot of power even here in Michigan. Wood and fossil fuels need to be saved for cogeneration and comanufacturing in winter. In my opinion the power of the future will be very intermittent. If we do not conserve then we are abusing the little children.