How to Create a Solar Panel Water Heater

Step-by-Step Guide

1. 1

   Step 1: Get a double-glazed unit for the sunlight to pass through.

   Glaziers and window manufacturers sometimes have scrap units for patio doors or large windows that can be bought very cheaply.
   
   Glass with a low-emissivity coating such as Pilkington K glass is ideal.
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   Step 2: Get a single-panel room radiator that is slightly smaller than the glass unit.

   Scrap yards sometimes have old radiators, or ask a plumber who is refurbishing a central heating system. , Use 12mm plywood for the back and 150mm x 50mm timber for the sides.
   
   Make sure it is deep enough to accommodate 50mm of insulation plus the radiator.
   
   The glass should exactly fit the box on three sides but overhang the box on the fourth side so that rainwater will drip off the glass when the box is set at an angle. , In the UK an angle of 35º from horizontal works well. ,,,,, You can route one pipe inside the box to make both pipes exit the same side of the box if your installation requires it. , Use threaded straight connectors rather than radiator valves to fit pipes that go straight out of the box. ,,,, This will create an airtight seal between the glass and the box and increase the thermal insulation. , 45º mitres on the two corner joints makes a smart finish. , If your hose is slightly too big solder straight connectors onto the ends of the tubes to increase their diameter. , You now have a solar panel ready to heat water.
   
   In order to have a functioning system you will also need a water tank, a water pump and (if the pump does not run on mains electricity) a photovoltaic panel and control unit to power the pump.
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   Step 3: Build a strong wooden box to fit the double-glazed unit.

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   Step 4: If the box will sit on a flat surface build a support so that the box can be installed perpendicular to the sun.

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   Step 5: Treat the outside of the box to make the wood water resistant.

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   Step 6: Glue aluminum kitchen foil to the plywood inside the box.

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   Step 7: Screw two radiator brackets inside the box to support the radiator.

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   Step 8: Insert a layer of 50mm thermal insulation slabs over the kitchen foil.

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   Step 9: Fit the radiator onto the brackets and drill 20mm holes in the side of the box where the pipes will come out.

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    Step 10: Plumb in the radiator so that two pieces of 15mm copper tube extends 100mm from the outside of the box.

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    Step 11: Spray the front of the radiator matt black using heat resistant paint

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    Step 12: such as that used for spraying the radiant parts of coal and gas fires.

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    Step 13: Screw two angle brackets onto the bottom edge of the box and bend them up to stop the glass sliding off the box.

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    Step 14: Run a bead of silicone sealant around the edge of the box and place lengths of electrical tape over the bead so the glass doesn't stick to it.

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    Step 15: Place the glass on the box and leave the silicon to set.

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    Step 16: Screw L section UPVC strips to the three sides where the glass is flush with the box to prevent rain ingress.

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    Step 17: Get rubber engine hose with an internal diameter of 15mm from a car parts shop and attach it to the 15mm copper tube with jubilee clips.

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    Step 18: Finished.

Detailed Guide

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