What do I need apart from the collector panels?
The following components are usually installed:
1. A pump to circulate the solar fluid.
2. A differential temperature controller to switch on the pump when the fluid in the collector is hotter than that in the hot water cylinder.
3. A non return valve to prevent thermo-syphoning. This is an undesirable situation which causes heat loss when the system is not operational, eg at night.
4. Filling loop valves.
5. A pressure relief valve, to prevent the system building up a dangerous pressure in a fault condition.
6. A pressure gauge to measure the pressure in the system, necessary at time of filling.
7. A means of fixing the collector to the roof, normally bolts or straps.
8. An air bleed valve to bleed air from the system.
9. An expansion vessel to accommodate expansion of the solar fluid as it heats up. The expansion vessel has an optional fitting kit to make things easier.
10. Copper plumbing, usually 15mm.
11. High temperature pipe insulation.
12. Solar fluid, a solution of propylene glycol, corrosion inhibitors and other additives, and deionised water.
13. A suitable hot water cylinder with an additional solar heat exchange coil.
Note that to commission the system a method of pressurizing the solar circuit is required. A cheap and easy way is here.
Items 1-6, shown outlined in green in the schematic below, can be conveniently purchased and installed in a package called a pump station.
Highly recommended is the addition of a heat dump circuit, which will prevent the solar circuit from boiling during a time of low water usage and high input (eg when the house is vacant in the summer during holidays. Shown in blue in the schematic, its components comprise:
14. Central heating radiator sized to match the peak output of the solar array (radiators are rated for a given output in kW, see manufacturers listings for information on this). The radiator is placed in the attic or somewhere else where waste heat will not be a nuisance or hazard.
15. Motorised valve controlled by solar controller. Note that certain controllers, eg Resol AX, do not support a heat dump.
Other items to consider are:
16. Surge protection device. Protects controllers from overvoltage caused by lightning resulting in high voltages on collector sensor cable. Not a common problem, but not a lot of money either.
17. Lead or aluminium flashing for a neat and waterproof pipe entry through the roof.
18. Unusual plumbing fittings. We stock a range of compression fittings, including some harder to get ones such as an unequal T which is 22-15-3/8" BSP, which allows the collector manifold to be connected to an automatic air vent and isolating valve, and to 15mm copper for the solar loop, and 15mm compression to 3/4" BSP which allow 15mm copper to be connected to a Flowcon pumping station.
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