Six fire engines and around 40 firefighters tackled a fire on Woolwich Church Street in Woolwich.
Most of a single-storey wooden storage container unit was damaged by fire. There were no reports of any injuries.
The Brigade was called at 1123 and Control Officers mobilised crews from East Greenwich, Plumstead, Greenwich, Eltham, Old Kent Road and Peckham fire stations to the scene.
The fire is being treated as accidental and believed to have involved solar panels.