Earlier quoted context omitted.
That is actually pretty insightful — pretty easy to get back the $3 that it costs. I can definitely see "free charge with purchase".
At $0.11/kWh, the Roadster at 53kWh would take almost $6 to completely fill. Though if these stations charge using solar power and store the power in a battery pack to discharge when a car hooks up, it could potentially cost them a lot less than $0.11/kWh, depending on the cost of building the station itself.
Also add maintenance of all those batteries and I bet you'd have a really hard time to motivate solar for economical reasons.