On a recent solar pv survey we were asked to look at an existing solar thermal installation which had been installed for over a year but the home owner was concerned the system wasn’t working properly.
The solar thermal system had been installed by their builder whilst having some renovation work carried out. What we found is unfortunately more common than you would think.
- System filled with water rather glycol – water is liable to freeze and crack the tubes and also has poor heat transference properties compared to glycol
- Copper pipe used instead of stainless steel, copper pipe will cause the system to loose heat via conduction
- Inadequate insulation of the pipe work – again this will lead to excessive heat loss
- Temperature settings on pumping station incorrect which meant that hot water produced by the solar thermal system wasn’t coming into the hot water cylinder efficiently
- No mixing valve installed (safety feature to stop the water in the cylinder getting too hot)
- “Blow off” valve was feeding back into water cylinder instead of a separate vessel allowing contaminated water to enter the cylinder
All of the above make the system highly ineffective and will give little contribution to heating the hot water. It will cost approximately £500 -.£600 to rectify and goes to show when choosing an installer make sure they understand the technology and how it works and use the correct parts. We are coming across these issues more frequently and offer system checks and servicing on solar thermal installations.