In September, volunteers installed a solar array on top of a two-story community center in the Dique da Vila Alzira favela, hoping it will prove that solar energy can be expanded to neighboring homes in this informal urban enclave, one of nearly 1,000 in Greater Rio de Janeiro, Brazil. In favelas, informal connections often siphon energy from the region's large energy companies because utility costs are high and incomes are low. While 97% of households are connected to the formal electricity grid, some households are paying for some of their energy while siphoning energy for certain appliances. While solar units in favelas typically plug into the existing energy grid, overall costs are lower because buildings are powered by a mix of free solar energy and power from the utility. Any excess energy goes back into the wider system. It's a step toward sustainability for neighborhoods left out of city and state policy that have been left on their own to handle garbage, plumbing and energy needs.