Solar Panel Construction

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I decided to make a hot water solar panel about 3 years ago,  I had some reclaimed copper tube  but I still had to buy about half the copper tube for the first panel as I finished up making two and had to buy every thing for the seconded one. Total cost if buying the lot is about £100 each. This excludes the glass as I was given this. My panel dimensions 1220mm x 1750mm.Aprrox 2 Square metres for each panel. I used aluminium angle 4x1x1/8 inch for the sides and 1/16inch aluminium sheet for the absorber  plate and panel rear. The side are pop riveted together by cutting a 4 inch peace of 2"x2" x 1/8 aluminium angle over the 4 corners and again pop riveting it, then fixing the rear panel sheet in place with more pop rivets. I used lots more aluminium angle of different sizes the retain the absorber  plate and glass etc this you can see in left-hand picture below. The exact size of aluminium pieces depends on the glass you have, my one's were seconded hand secondary glassing units. The absorber  plate has about 40metrs of 15mm copper tube in it fixed to it with about 150 copper saddles and about 100 copper elbows in the construction.See http://www.bigginhill.co.uk/solar.htm This was the site  that gave me the basic ideas but they used wood for the case but aluminium works out cheaper and a lot longer lasting.

I have been monitoring  the system over the last two years and even in winter sunshine the tank temp can be raised by more than 10°C  Summer sun can raise the tank temp by more than 40°C above ambient incoming water temp (My tank holds 170 litres) which is quite a saving and as my main heat source is oil I estimate that the costs of the panels and new hot water cylinder will still repay in two years and less if the oil keeps going up.

Text Box: Were arrows are shown all 4 side angle pieces need to have insulation  fixed to them. I used strips of vinyl floor tile this is were the absorber plate will be fixed.                                           EMPTY BOX                                                                                                    BOX WITH COPPER TUBE

The finished panel  hot water is pumped with a central heating circulating pump and controlled with a differential thermostat see circuit diagram I used below:-                              

Text Box: D1 and D2 are IN4148 type not critical RL1 any suitable 12 volt relay OP amp = LM324 or similar Darlington transistor = TIP 121 Pot = 1K 20 turn 10 volt ref = LM3040-10                

The two diodes act as temperature sensors Di is mounted at top of panel inside the casing D2  about 1/3 of the way up on hot water cylinder. See diagram bellow of typical hot water circuit with solar panel using a dual coil indirect cylinder.

                                                                                                               

 

To add extra panels (my system has two) just connect them in series, i.e.- the return from the first panel to the flow of the second one.

                   

                 Some more pictures of my panels you can see from the right-hand picture how the casework is put together