Concrete footers
By St. Petersburg Coastal and Marine Science Center
2011 (approx.)
![Concrete slabs on a gravel roof.](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/media/images/Solar1desLG.jpg?itok=NP7-foGL)
Detailed Description
Concrete footers will support an elevated array of evacuated-tube solar collectors to supplement the natural-gas boiler (green boxlike structure at back).
Sources/Usage
Public Domain.