Sealing high temperature solar joints

Sealing joints on solar panels has proved problematic, especially if the solar pump is switched off during periods of hot sunny weather. Plumbers are quite adept at fitting compression joints that seal aginst water, however if high pressure steam is generated within the panel, previously water-tight compression joints can start to pass steam. This leads to the solar system de-pressurising and it ceases to operate correctly.

However, sealing joints against steam can be done easily enough with graphite based sealants. One such example is shown below. The manufacture recommends that it is used in conjunction with hemp.

It is also the authors' experience that stainless steel pipe joints also more resistant to steam leaks than copper compression joints (without the graphite sealing compound).