Portland has been seeing a substantial increase in the number of ecoroofs integrating photovoltaic (PV) or solar water-heating panels directly above the vegetation. The tenth such combo was recently completed, bringing the City to over 100,000 square feet (sf) of ecoroofs that integrate solar panels over parts of their design. The Village at the Headwaters, a senior affordable housing community, was the first to combine the two, installing a small solar water heating system over a portion of their ecoroof in 2007. 85% of installations have occured since 2010, some of which cover nearly the entire vegetated roof.
This combination appears beneficial to both systems: the dappled, shifting shade from the panels limits plant exposure on dry, hot days and curbs the need for irrigation systems. The solar panels function more efficienctly in the cooler microclimate provided above the plants and soil.
The projects have been a mix of new construction and retrofits on predominantly commercial buildings. Portland State University and the City of Portland are currently researching this relationship between building energy and the other ecosystem services provided by ecoroofs.