SAN DIEGO -- More than four dozen solar-powered parking meters are being installed in downtown San Diego as part of a pilot project to evaluate the effectiveness of the technology for use throughout the rest of the city, Mayor Jerry Sanders announced Wednesday.

The 51 meters run on solar-generated electrical power, accept credit cards, prepaid parking "value" cards or coins, and can be installed on existing poles, according to the mayor's office.

According to Sanders' office, the solar-powered mechanisms are more environmentally friendly than the existing meters because the devices do not require the use of disposable batteries.

The meters, designed and developed by San Diego-based IPS Group, also allow for better parking management statistics, ease of control over parking meter rates and better displays and instructions for users, according to the mayor's office.

The solar-powered meters will be installed along Fourth, Fifth and Sixth avenues, West G Street and Market Street.

During the four-month pilot project, the city will also test new parking sensors that work with the solar-powered meters to track parking activity at individual spaces.