Solar Panels (from £395) for domestic hot water, swimming pools and underfloor heating. Evacuated Tube Solar water heating. All Things Green (reduce,reuse, recycle).

Solar Water
Heating
Frequently asked Questions

Evacuated Tube Solar Hot Water Panel (20 tube)

These top-of-the-range solar panel heat collectors are suitable for heating domestic hot water, underfloor heating, swimming pools, etc - even in the winter! One unit is adequate for an average household (3-4people), and it is modular, so you can add more if required. A single panel is sufficient for a 200litre cylinder, but you can fit 2 or more for high water usage, or for heating swimming pools or underfloor heating. Some types of renewable energy are only available in certain locations, however free solar heating is potentially available to almost every house in the UK! Every house should have one -really! And with an overall efficiency of almost 80%, they are much more efficient than electric photovoltaic solar panels (efficiency of 7-15%). And if we compare them on a like-for-like basis, the price of a Solar Water Heater is around 30p/watt (compared to £6+/watt for solar photovoltaics!)

Please contact us for further information or advice

pictures of an evacuated heat tube's business end.

This high tech unit concentrates the sun's energy at the tip of the copper 'heat tube' - like a solid state magnifying glass!

The vacuum tube solar panel has been around for over 10years, and has proved to be reliable and dependable. The vacuum tubes consist of a double wall glass tube (made from strong borosilicate glass ie pyrex) with a space in the centre which contains the heat pipe. The sun's radiation is absorbed by the selective coating on the inner glass surface, but prevented from re-radiating by the silvered innermost lining. This is in effect like a one-way mirror which has been optimised for infra-red radiation. In fact it is very efficient, of the sun light's energy hitting the tube's surface, 93% is absorbed, whereas only 7% is lost through reflection and re-emission. The presence of the vacuum wall prevents any losses by conduction or convection - just like a thermos flask. Because of this, the system will work even in very low temperatures, unlike traditional flat plate collectors. This is why this system can be used to heat up water at the South Pole Antarctic Science Base - where ambient air temperatures can drop below -40°C

The heat transferred to the tip of the heat pipe is in turn transferred to a copper manifold in which water circulates to heat the domestic hot water tank. If a tube is placed in direct sunlight on a summer day, the tip temperature can reach 250°C - so the system easily heats domestic hot water cylinders to 60°C even in cooler weather! The manifold is heavily insulated with a 2" thickness of pre-formed rockwool to keep the heat in. Unlike flat plates, these headers are so well insulated that they should not require antifreeze in normal operation - the temperature of the header is unlikely to fall below 10°C even in very cold weather. The more advanced solar controllers include a low-temperature facility- should the temperature of the collector fall below a defined level, the pump will operate to allow the the water at the bottom of the tank to heat the collector slightly. In normal conditions, this would never be necessary - but it acts as a good safety margin.

Swimming Pools

Swimming pools are an ideal application for solar water heating, as the temperature required is quite low - under 30°C. Most installers will recommend flat plates to keep the price down - because the amount of panels required is much larger than for heating domestic hot water - however, if you can buy a high efficiency evacuated tube solar panel for the same money - you might as well enjoy solar heated pool water all year round - instead of just in July and August! If you used flat plates. A rule of thumb for calculating what you need is to fit the equivalent of 50% of the pool's surface area. For Vacuum tube panels, this is reduced to 25% - and of course, they will carry on working in the autumn, winter and spring. The solar panel is 2.25m2 so each panel will heat 11m2 of pool area. A 40m2 pool would only need 4 solar panels. Compare this to the cost of heating a pool for a year!

Installation is very simple. If you have chlorine you will need to fit a stainless steel heat exchanger (this is because chlorine causes copper to corrode). If you dont have chlorine, you can simply put the solar panel in-line with the pool filter, so that the pump directs water through the panel before returning it to the pool. As the panel will NOT radiate heat on cold days, heat losses will be confined to your pipe runs only - so you do not necessarily need a controller, although one can be fitted, to control a 3-way solenoid valve to divert the water via the panel when the panel is hotter than the pool water.

How Much Heat Will I Gain?

Average Daily Irradiation (Insolation) Figures for Each Month of the Year:

(Solar energy reaching each 1m2 of the earth’s surface at UK latitudes)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
MJ/m2 day	2.3	4.2	7.0	11.6	15.0	18.0	16.0	13.0	10.0	6.0	2.8	1.7
kWh/day per m2	0.64	1.17	1.94	3.22	4.17	5.00	4.44	3.61	2.78	1.67	0.78	0.47
Heat Gain from 1 solar panel per day	1.15 kWh	2.11 kWh	3.49 kWh	5.80 kWh	7.51 kWh	9.00 kWh	7.99 kWh	6.50 kWh	5.00 kWh	3.01 kWh	1.41 kWh	0.85 kWh

Key Benefits of Vacuum Tube Solar Panels:

High temperature output even in cold weather
Warms water even during winter, as long as the sun is shining
Produces heat even in overcast weather
Easy to fit
Higher efficiency and greater installation flexibility with heat to many of the more expensive brands on the market - as the tubes and headers are all manufactured in the same factory by an OEM supplier.

Solar Water Heating FAQ.

Please contact us for further information or any advice that you may require.


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