Flat Plate Solar Panels

Typically these simple panels come in aluminium or plastic box form with a surface area of around 1.5 - 2.5 metres square, the top is glazed with special solar glass and the box construction is well insulated to retain the suns heat. They can be either integrally mounted into the roof, or more commonly fixed over the existing roof tiles.

Sunlight passes through the solar glazing and strikes the absorber plate, which heats up, changing solar energy into heat energy. The heat is transfered to liquid passing through pipes firmly attached to the absorber plate. Absorber plates are commonly painted with "selective coatings" which help to absorb of UV radiation, but are reflective to infrared so they retain much better than simple black paint. Absorber plates are typically manufactured from sheet copper and use copper pipework to transfer the heating medium from the collectors to the hot water cylinder or swimming pool heat exchanger.

Overheating of the transfer liquid during high insolation periods has historically always been a problem with old style solar thermal collectors. This problem has now been overcome by an innovative design of high efficiency collectors from a Spanish manufacturer. These new collectors do not have any fluid inside them unless they are actually working, IE when there is a demand from the hot water cylinder. Likewise, having no fluid when not actually working they avoid the risk of freezing up in winter.

The way they operate is remarkably simple, the special solar collector is mounted onto the roof in the normal manner and two small pipes, being a flow in, and a return out, drop down inside the building to the solar water heater cylinder usually located within the airing cupboard. A temperature sensor within the hot water tank monitors the stored water temperature and another sensor located inside the solar collector monitors the panel temperature, when the panel temperature is 4 Degrees Celsius or more than the stored hot water temperature a special twin circulation pump forces water up and into the panel where the heat energy is harvested and the return pipe delivers it back to the hot water tank.

When the hot water tank is satisfied and at temperature or if the weather clouds over and solar radiation is lost the panel sensor stops the circulation pump, and the transfer fluid drains back by gravity into the solar store tank. When further solar energy is available the whole cycle starts all over again.

The system is simple and reliable, no antifreeze is required and the collectors cannot overheat so the installation is far safer and superior to any basic old style flat plate collection system.

The average cost of the new self draining system, installed into an average home is in the region of £5000.00.