Detailed Info

EVACUATED TUBE SOLAR HOT WATER PANEL (20 tube)

These top-of-the-range solar panel heat collectors are suitable for heating domestic hot water, swimming pools etc – even in spring and autumn and to some extent winter! One unit is adequate for an average household (3-4people), and it is modular, so you can add more if required. A single 30 tube panel is sufficient for a 200litre cylinder, but you can fit 2 or more for high water usage, or for heating swimming pools. Some types of renewable energy are only available in certain locations, however free solar heating is potentially available to almost every house in Ireland. Every house should have one -really!

Photo above right: An assembled Ecologics 20 tube standard panel

What Size is the collector?

The 20 tube 47mm collector is 1760x1500x130mm (LxWxH)
The 30 tube 47mm collector is 1760x2170x130mm (LxWxH)
 

Solar panels with integrated water tank

The picture below shows a more basic design, is commonly employed in hot countries. This type of system does not employ heat-pipes; instead the water fills the tubes, which in turn heat the header tank by convection. This system is far more basic and less efficient, but has obvious advantages: no requirement for electric power, no controller, pipe insulation etc required and is very low-cost. However, it is less functional, too large to appear roof-integrated, cannot accept pressure system kits and cannot be used with a standard domestic hot water tank. However, we plan to import some of these for use in remote locations and especially in dairy farms where they could supply hot water for hosing down bulk tanks etc.

Phot above: 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. Our twin-wall vacuum tubes consist of a double wall glass tube (made from strong borosilicate glass often known as pyrex). There is a narrow gap between the two layers of glass which is under a vacuum, and this provides very effective insulation against heat loss. The centre of the tube contains a copper 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 our 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 in many situations they will not require antifreeze. 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.

Sample Schematics:

1. ‘Hot Tube’ coil screwed into immersion heater flange

Cheap and easy to install. Ideally requires immersion heater flange to be located in the lower part of the cylinder. Unfortunately, most modern hot water cylinders have top-mounted immersion heaters, which will not allow high efficiency when used to facilitate solar heating

2. Direct heating(simplest method)

Simplest method. Quite efficient, but in areas of hard water, eventually, the solar collector will get ‘furred up’ with limescale, which will reduce efficiency. Easy to retro-fit to an existing direct or indirect hot water cylinder.

3. Twin coil hot water tank

This is the best method, but requires the added cost of a twin coil water cylinder. We can supply these at attractive prices, with the added advantage of a double layer of insulation(50mm), keeping heat losses to a minimum. Please contact for details

Key to Diagrams:

1. Ecologics Solar manifold with 20 Vacuum Solar Heater Tubes
2. Pressure Gauge
3. Automatic Air Bleed
4. Drain Cock
5. Expansion Tank
6. Gate Valve
7. Single Check Valve
8. Double Check Valve
9. Filling Loop
10. Circulating Pump
11. Pressure Relief Valve
12. Overflow

What else will I need to go with this panel?

It depends on your application and the method you employ. The simplest system would be based on thermo-siphon (convection or ‘gravity feed’). The panel would be mounted lower than the hot water cylinder, and not too far away from it. When the sun shines, the hot water will rise, and displace the colder water which returns to the panel. This system requires no additional energy, no control system and is self-regulating, simple, cheap and effective – but not very convenient for most situations. In this case, you will only require the header tank or pressurised system kit plus copper tube and insulation.

However, in most situations where the panel is roof-mounted, a typical system would normally include:

• Solar panel
• Solar Hot Water Cylinder
• Expansion Vessel – correctly sized for your system and High temperature rated.
• Pumpstation – includes Resol BS3 controller, Sensors, Pressure gauge, Filling points, one way valve and flow meter
• Copper pipework, fittings and High Temperature pipe insulation (obtain from any good DIY or Builders’ Merchant) or Stainless Steel pipe work (available from Ecologics)

A note about pipework

There are some flat plate systems, such as the Solar Twin system, which use plastic pipework to make installation easier and to reduce costs. Whereas this pipework may be ideal for flat plates, it is definitely not adequate for evacuated tubes. On a hot sunny day, flat plates may heat water up to a temperature of 60°C. Evacuated tube systems are capable of heating the water beyond 140°C. Most plastic pipework is able to stand no more than 90°C – so you should always use copper or stainless steel to connect the panel to your domestic hot water cylinder, and this pipework should be insulated with high temperature (HT)insulation – not the usual light foam commonly used, as this may melt at high temperatures. There are two types of Insulation – Class O can be used at temperatures up to 105C, and is suitable for open vented systems. HT Armaflex should be used where there is a pressure kit, as water in this system can reach 120C without boiling.

What about 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 can be reduced to between 25% and 33% – and of course, they will carry on working on sunny days in the autumn, winter and spring. The Ecologics panel is 2m2 so each panel will heat up to 10m2 of pool area. A 40m2 pool would only need 4 Ecologics 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). These are available from pool suppliers (they are needed for conventional heating methods for the same reason). If you don’t 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 through the panel when the panel is hotter than the pool water.

A Word on Flat Plates

Flat plate collectors provide useful heat mostly during the summer months in Ireland due to their high heat losses during cold or windy weather. When the ambient temperature drops and the wind picks up, the heat loss can easily exceed the heat gain. However Flatplate collectors can be used in situations where aesthetics call for something less conspicuous than vacuum tube systems and where the heat demand is mostly concentrated in the summer months, for example a hotel or B&B or a summer home.

Vacuum tube collectors will provide useful heat for 12months of the year, as long as the sun is shining, and can even produce heat in overcast weather. (In April, an overcast day without any sunshine is still able to heat a 210litre hot water cylinder to 40°C)

Brand Names:

The Ecologics panel is pretty much identical to several other panels on the market (from Sweden to Germany). This is because the Ecologics manufacturer produces panels for some of the biggest names in vacuum tube solar panels – These are simply re-branded once they reach Europe. Happily the comparison doesn’t offend us, because we don’t overcharge for our products. We’re sorry if you bought a panel that looks remarkably like ours, but costs a lot more!