Solar Systems

Solar Systems

The sun is by far the most abundant source of energy available on earth. Energy arriving at the earth's surface by way of solar radiation over a period of 40 minutes is the equivalent of the power used by the entire population of the earth in one year.

A well designed solar water heating system installed in a family house which previously used an electric immersion heater to heat water can save in excess of half a tonne of carbon dioxide emissions per annum.

How do we compare to Europe?


Population (Approx)

Approximate area of solar collectors installed in 2004 (in square metres)

Austria 8 million 182,594
Denmark 5 million 20,000
Germany 79 million 750,000
Netherlands 15 million 26,300
UK 55 million 25,000

Source: ESTIF, June 2005

Environmental issues and the spiralling rising prices of oil, gas and electricity are now giving a new impetus to the UK solar thermal market. As the energy costs of homes increases, it is reasonable to expect that a solar water heating system will add value to a property as long as it is designed and installed properly. Unfortunately, the lack of local experienced installers has meant that most solar water heating systems have, to date, been installed by "HARD SELL" companies with their own travelling installation teams. This sales and installation technique has resulted in extremely high prices being charged and low consumer confidence in back up service.......until now.

The quality manufacturers have, for a long time, wanted their product installed by competent local installers, and now most will only supply their goods to bpec qualified companies. Gas Technical Services have invested in this training and are now qualified and approved to design and install Solar Hot Water Systems approved by the Solar Trade Association.

Do we get enough sun in the UK for a system work?

There is a widely held opinion that the UK does not have enough "sun" to make solar systems worthwhile. But, in fact, parts of the UK have annual solar radiation levels equal to 60% of those experienced at the equator.

The Department of Trade and Industry (DTI) commissioned a two year monitoring programme of four domestic hot water solar systems located at Troon, Tewkesbury, Luton and Croydon. The results showed that systems provided an average of approximately 70% of the annual hot water requirements at the four locations. All four systems worked in Winter as well as Summer with 16 - 18% of hot water needs being met in December and January and almost 100% of hot water needs being met in both July and August.

A further recent project supported by the DTI monitored eight solar water heating systems side by side. The project involved taking a daily draw of 150 litres (33.3 gallons) of hot water from the solar hot water cylinders of eight systems mounted side by side at Cranfield University and measuring the heat contribution provided by the eight systems. The annual heat energy contribution of the systems was then predicted from the results with the projected contributions ranging from 1,000kWh to 1,350 kWh per annum.

How much energy do I use now for hot water?

For water heating, a typical UK house uses 5kWh per day of useful energy (that is the energy content of the water leaving the taps). This figure can vary considerably from house to house, dependant on household size and water usage.

The actual amount of delivered energy (the energy registered on a gas or electricity meter) can be considerably higher, particularly in summer. Running a boiler with a continuously burning pilot light and uninsulated hot water pipe runs for small quantities of hot water reduces efficiency considerably. Even electric immersion heaters may only manage 50% efficiency in terms of useful energy at the tap, boilers considerably less.

How much solar radiation do I receive where I live?

Maximum power on a cloud free day occurs at solar noon at any location. The Meteorological Office has been recording solar radiation for more than 30 years and has produced maps showing the geographical distribution of solar radiation for the UK.

Solar Gain


This graph shows variation in annual mean values of solar irradiation on a south facing 30 degree incline plane in the UK in kWh per metre square.

As you can see from this, we are fortunate in West Wales as being the second highest in the country, receiving approximately 1,100 kWh per metre square.

But what if it is a cloudy day, will I still benefit?

When the sun's rays hit the earth's atmosphere some of the radiation will be scattered due to cloud cover. A portion of this scattered light reaches the earth and is known as diffuse radiation. It is usually assumed to come equally from all over the sky. Without diffuse radiation the sky would appear black. What we normally call sunshine, i.e. the proportion of the sun's rays appearing to come straight from the sun, is known as direct radiation. So the simple answer is yes, even with cloud cover, some diffused radiation will still find it's way to your solar collector.

How does a solar hot water system work?

From the diagram, you can see that one of the main differences to a conventional hot water system, is that the hot water cylinder (Thermal Store) has two coils inside it, whereas a conventional system Solar Diagramnormally has just one.

Fluid is pumped from the coldest part of the cylinder (bottom), up to the solar collector, where the fluid picks up heat from the suns radiation, before being pumped back down to the lower coil in the cylinder

The boiler is then coupled to the top coil within the cylinder to provide back up hot water if required. The solar fluid contained in the solar circuit is made up of water, inhibitor and glycol ethylene to protect the inside of the pipework from corrosion and freezing. The fluid in the heating circuit remains the same as any conventional system and contains water and inhibitor. The water surrounding the two coils within the hot water cylinder never makes contact with the fluid within the coils, as this is the water which will be delivered to your hot water taps.

Because it is not uncommon for the water temperature within the solar collector to exceed boiling point, pipework to and from the solar collector cannot be simply soldered, it must be brazed or compression joints used.

Why we prefer the Vaillant product.

Whilst it is true that there is a large selection available within the UK market, we prefer to favour one particular Manufacturers product. As with their condensing boilers, the quality and reliability is legendary, and Vaillant have not disappointed us in the Solar market either. Everything is of the highest quality and beautifully designed so that each component compliments the next. In addition, they have a sound and strict environmental policy in relation to the materials used to produce their equipment.

The environment (Vaillant's Policy)

The design of all Vaillant products takes into account the subsequent recycling and/or eventual safe scrapping of each component used. Vaillant’s in-house rules set strict standards in this respect. The selection process used for choosing raw materials includes full consideration of their recycling characteristics, and of the breakdown and separation properties of subassemblies. We also take fully into account the environmental and health hazards involved in recycling and in the disposal of non-reusable waste items.

The Ozone Depletion Potential (ODP) is a number that refers to the amount of ozone depletion caused by a particular substance. All Vaillant boilers have an ODP rating of 0.

The Global warming potential (GWP) is a measure of how much a given mass of greenhouse gas is estimated to contribute to global warming. Vaillant’s boilers have an official rating of 0 in this category.

The foam insulation used in all Vaillant boilers is manufactured using substances that do not contribute in any way to the ODP and subsequent disposal of the foam will not release any harmful emissions that lead to global warming.


Vaillant endeavours to keep the amount of transport packaging used for its equipment to the bare minimum necessary. Subsequent re-use is taken into account when selecting packaging materials. High-quality cardboard has long been a valuable secondary raw material for the card and paper industry. The sections of EPS are required in order to protect equipment in transit. EPS is 100% recyclable and CFC-free. The foil-wrapping and securing straps are likewise made of recyclable plastic.

The Product


auroTHERM exclusive vacuum tube collectors

The auroTHERM exclusive vacuum tube solar collector have been designed to give maximum energy absorption and are easy to install in various applications. As the collectors work on diffused solar radiation as well as direct sunlight, they will even generate small amounts of energy on partially cloudy days. Multiple panels can easily be fitted together as required for larger systems.


auroTHERM plus

The auroTHERM plus flat plate collector has a special anti-reflex coated toughened 4mm thick glass. The collector consists of an ultrasonically welded copper grid with a high selective absorber coating and 60mm rear and side insulation.
The whole assembly is encased in a polished aluminium frame for a neat construction. The collectors can be connected in series in horizontal or vertical orientation to suit the available roof space.



Instant hot water with the auroSTOR cylinder.
A stainless steel storage cylinder available in 3 different volumes to meet all of your requirements.

This twin coil unvented solar cylinder manufactured from stainless steel has a 25 year warranty on the shell. Each cylinder features two sensor pockets for simple straightforward connection of the control sensors and a 22kW rated coil for a rapid heat up, and is delivered with a 3kW back up immersion heater as standard.

Insulation exceeds CHeSS best practice and heat loss is as low as 0.08kW/h.


auroMATIC 560

Easy and intelligent control for your solar system.
auroMATIC offers three time periods for auxiliary cylinder heating giving the end user total control over the availability of hot water. The control monitors the temperature of the collector and of the cylinder. When sufficient solar energy is available the control switches on the solar pump unit to charge the cylinder. If there is insufficient solar energy available the control will automatically determine when the auxiliary heat source is required.

For a FREE survey and no obligation quotation contact us on (01646) 683845.

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