using parabolic trough collectors. i'll just pick a number such as 4.

set up the plumbing such that in the winter the working fluid passes through the one time, much the same as in a flat plate collector.

then during the summer, probably using some values, set up the plumbing such that the fluid passes through all the collectors, i.e. output of panel one is feed to the input of panel 2, output of panel 2 is feed to the input or panel 3, etc.

set up this will the panel will produce low grade heat to be used for space heating.
Then, in the summer the panels will produce steam. Use the steam to run a steam generator.  use the condenser heat to provide DHW and feed the electricity to the grid.  Using steam will double, maybe even triple your efficiency.

something ala:
http://engineersformyanmar.blogspot.com/2007/08/how-to-build-solar-generator.html
http://www.popularmechanics.com/science/earth/4232571.html