Lumin Innovative Products, a small four-person company, has successfully deployed solar-powered WiFi access points at the Pearl Street Mall in Boulder. Using its LightWave AP-1000 access points which come with either one or two panels, this free WiFi network covers a six block area.
Although it cost $10,000 to deploy the network, maintenance costs should be very low, with only the rechargeable batteries needing to be replaced every so often. The panels themselves are built for 25-30 years of service. Only 5 hours of direct sun (with longer periods under less optimal conditions) are required to completely charge the batteries which will in turn power one LightWave for 72 hours.
Source: Pocket PC Thoughts