Well it would seem GM would be able to sell a lot more GM Volts if people were comfortable they wouldn't run out of power and get stuck. Seems like GM would be kicking in money for these charging stations. Second is you are forgetting the Sun doesn't charge anything for the power it generates. Sunlogics charging stations are powered by the Sun.
Iwondertoo- my take on this GM deal is that GM will purchase the solar caps and offer the electrical charge free but recover some amount by supplying the electrical surplus to the dealerships. It is GM that stands to benefit by this promotion (auto sales,PR and any excess electrical generation) and therefore only GM that can reasonably foot the bill.