Solar Site - Solar Panel

Solar Panel Installation

A personal record of my green initiatives, My Solar panel Installation using evacuated tubes / panels to provide both hot water and heating.



My original Solar Panel Installation which came as part if the initial kit, purchased from The Solar Shop comprised of two panels  , one 20 tube and one 30 tube
each tube is 58mm Diameter by 1800mm / 1.8 meters long
The 30 Tube array including the panel is 2420mm wide by 2010mm high = 4.9m2
The 20 Tube array including the panel is 1680mm wide by 2010mm high = 3.38m2

My original solar panel installation - South Facing with large domestic solar panel of 50 tubes over 2 panels.

large domestic solar panel and radiator dump





Large Solar Panel After approx 8 month use I was so pleased with the performance I increased the system by another 2 panels with 20 tubes in each to bring me up to 90 tubes in total. (I have now run out of south facing roof space.) The aim of this was to effectively oversize the system to make use of the sun throughout the year. I had all the other main components capable of taking the extra heat generation and therefore it was just a case of plumbing in two more panels and increasing the size of the expansion tank which I found both on EBay at a very competitive price.
The heat output of this system at peak performance with the sun perpendicular to the panels is approx 750 watts per square meter. therefore I will generate 11.2 Kw or 39300 BTU's of energy. As you will see not far of the output of a small domestic boiler though mainly for a few hours in mid afternoon.

Installing the Panels

Before I started - I ensured to roof itself was sound and capable of taking the weight.  The house is 90 years old so the roof beams were sturdy and very thick compared to a new build truss setup. However for piece of mind I installed  another 6" X  2" beam inside running under where the three lower panels sit, keyed into the loft wall at both ends. Prior to doing this I also removed all tiles and laid a new breathable membrane and new batons were put down as I don't intend to do any further repairs down the line for many years to come.

The first Panel - This is the largest 30 tube array ,the frame was bolted together and squared up before lifting directly on to the roof - they are reasonably light but large and awkward so to be on the safe side a rope was taken over the apex of the roof and the weight was taken from the other side  while the panel was lifted into position with relative ease.  Four holes were drilled straight through the concrete tiles with care and four stainless steel bolts put trough the roof. Noggins were placed inside to take the bolts as it was not always possible to line up with the original roof beams.  The Bolts then had a liberal dose of silicone sealer placed in the hole before fitting the supplied bitumen washers and steel domed washers and nuts to secure the frame.  The remaining three panels were more or less a repeat performance except the lower portion on the lower panels are strapped down as no loft access  was possible. One point I did observe when installing, All holes that were drilled through the concrete tiles were made on the top of the tile ridge as opposed to the tile trough to reduce water ingress, an important part which was followed throughout the installation

Installing the Evacuated Tubes.

Firstly place all the lower plastic holders into the frame on the bottom rail, unscrewing all the cups that hold the bottom of the tube, these are then replaced one by one as the tubes go in.

A task that was fairly easy but repetitive and great care was taken not to knock the tube on the concrete tiles on the way up. The Tubes have a copper bulb which fits into the manifold to transfer the heat and the manifold hole has a rubber gasket that's quite tight to hold the tube but also giving some movement. All that is required is to smear a light coating of heat transfer paste onto the copper bulb and and feed the bulb into the manifold hole. I found it easier to bull the bulb out of the tube a few inches, insert it into the manifold hold then push the glass tube into place. occasionally a small amount of washing up liquid helped out getting the tube in though in most cases not required. Finally screw the bottom plastic caps up securing the tube in place.


The flow of glycol in the system entered the header of the lower panel and was then taken up to the upper panel before entering the roof space. Needless to say any external plumbing is well insulated and and kept to a minimum , staying with 22mm as this is what the headers are presented as.  The actual pipe through the roof is 15mm with reducing couplings at either end of the four panels and again the pipe going through the roof is sealed with Silicone.  I have seen many lead kits (pricy) to provide a weather seal , however I made sure I drilled on the tile ridge ( as opposed to the trough) and holes were 16mm for the 15mm pipe to allow for some expansion but easy to seal. A liberal but not overdone application of silicone around all holes has proved successful with no leaks whatsoever, this goes for the pipes and the securing bolts that pass through the roof.


Just a glance up on the roof every now and again, nothing more than that.  We did however have a very heavy and unusually heavy snowfall and cold spell during the days  in March 09 (I think). To my satisfaction , and despite a heavy snow covering over the tubes, the winter sun was still penetrating the snow and heating the water  and the header temperature reached +20oc and  -2 outside. This was my only period of maintenance , sweeping some of the snow off to improve the efficiency as the vacuum in the tubes was good enough so as not to provide enough heat to melt the snow. I also keep a eye on the pressure reading on the pump station, and I have done a small top-up but which i have put down to some air in the system eventually working its way out of the air vent. Remember I also have several radiators and these also collected a little air but by no means was this excessive and the system has been stable throughout the summer.

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