With roof mounted panels, especially your low slung ones trying very hard not to attract attention
you have only a few options. One fix common to the US southwest desert region is add extra capacity, more panels and overvolting; say 60V or 72V system to be able to utilize 48V on hottest days. Expensive but effective.
I admire your work: http://www.otherpower.com/images/scimages/2333/P3160308.JPG
use radiative, conductive and convective cooling schemes. Also use every trick to keep non-generating-area sunshine from being absorbed.
More heat could be radiated from panel backs, ie: white paint + adding more surface area via rough sanded surface or fine grooves. Radiated heat is mostly infrared and acts like light so remember the IR shine shouldn't shine on adjacent cooling fins or be reflected right back by roofing. Having panels in close rows puts heat streaming off back of 1st panel onto 2nd panels front, that then dumps its heat onto 3rd panel, etc. I've read where an objects heat load can be reduced by 20% using passive heat shedding design. Painting the front aluminum frame bright white would be something easy too.
After the concrete is fully cured, painting your roof bright white would reduce the areas overall temperature, panels might absorb more reflected light as heat but have cooler air around them to help convection cooling. Probably slight overall gain.
Consider how to make "smokestack" convection work in your favor, a false roof platform that helps reflect light back towards sun (missing the panels) while promoting a better draft both above and beneath and channeled to reduce panel temperatures....
Conductive cooling could be making sure individual cells are not suspended in air, but have the backs in contact with a larger mass to keep the absorbed heat flowing instead of just super-heating the air around it...