Ballast

Ballast is added weight used to hold equipment or a mounting frame in position. In home energy work the term appears most often with flat-roof solar PV mounting, where concrete blocks, trays or other specified weights help resist wind uplift, sliding and movement without necessarily relying on fixings through the roof covering. Ballast is not a rough extra weight that can be guessed on site. The amount, layout and protection layer depend on the mounting system, roof construction, roof covering, wind loading, friction, roof pitch and any planning or structural constraints.