Why Solar Water Heating

‘Why Solar Water Heating’  

Hot Solar Water Wall integrated cladded solar thermal panels at University of Exeter

Hot water heating (on average) accounts for approx.. 30% of your annual energy bill in the United Kingdom.  With a thermal solar system, you could generate enough solar energy to heat up to 70% of your hot water FREE, year after year!   With a 35+ year life expectancy, the savings are considerable in addition to giving you energy independence.

  • Generate up to 70% of your hot water FREE
  • 35+ year life expectancy; save on your energy bill year after year
  • As fossil fuel prices continue to rise solar will save you more and more



People ask “What is the pay back?” for solar thermal systems. Well, first and foremost it does have a payback. If you buy coal, oil or electricity or gas the supplier does not offer you any pay back at all. No matter how much gas, oil or coal you buy and no matter how long you buy it for, you never get your money back. You have to service, maintain and renew you fuel burning equipment. Similarly, the electricity company never offers you a payback.

Hot Solar Water Solar Thermal Domestic Solar Water Heating Norfolk

Various government bodies define sometimes payback as the annual fuel bill savings divided by the capital cost.  This is simply inaccurate misleading and wrong.

If you take a proper view of payback, you have to factor in future energy increases, take account of inflation, look at the savings in boiler servicing and the ability to make a boiler last longer any add in the parasitic losses that a solar thermal system suffers. Doing the sums properly most thermal systems offer a pay back of between 6 and 12 years, depending on the fossil fuel displaced, the future fuel inflation factor you use and the amount of hot water you use.

If the product is built as part of the housing infrastructure it will last for around 30 years with minimal maintenance. If the product is built into a home in the course of construction the pay back period declines rapidly.

Although payback is one way of looking at the cost it is perhaps more accurate to look at the return on your investment that solar thermal offers. Typically the financial savings of a good solar thermal system will be equivalent to a tax free return on investment of between 8% and 12%.

Help the Environment

Heating your hot water is a major contributor to carbon emissions.  Carbon pollution is causing global warming.  Your solar thermal panel can save as much as 1 tonne of carbon dioxide per year, depending on the fossil fuel displaced.

Hot Solar Water Solar Thermal In Roof Falmouth, Cornwall

Our panels work on a carbon zero rating, emitting no carbon pollution and no harmful greenhouse gases whatsoever.

Of course, energy was used to make the panels, but even this is recovered after only 2 years use. For more information about the environmental benefits of renewable energy you may be interested in The Energy Age.


A full explanation and figures are given in our Carbob Payback article. We look at a typical UK home and just how much CO2 could be saved when using a Thermosolar solar water system. The results are quite incredible!

The Carbon Footprint of our Solar Thermal Panels

How efficient, really, is the carbon payback on your solar panel?

To understand the Carbon Payback of anything manufactured, one must first know it’s Carbon Footprint.


The benefit of hot water solar panels is twofold; you reduce your home energy bills by heating your water supply with the free energy of the Sun, and secondly, they reduce your carbon emissions by freeing you from the dependency on high polluting fossil fuels. But not all solar panels are made equal, in fact, the carbon footprint of solar panels must be reduced to as small as possible, if they, like our Solar Panels, are to save huge quantities of carbon over their lifetime.This article takes a look at the manufacturing process and materials involved in the production of our solar panel; and how these contribute to a low carbon footprint, giving you a high performing, carbon saving solar panel.

The logistics and transport and handling of these materials must all be considered when calculating an exact carbon footprint of anything from a cell phone to a solar panel.

Hot Solar Water – In Roof Commercial Solar Thermal Swimming Pool Heating


Materials used, and where they are sourced from, contribute to the carbon footprint of any manufactured part.

Materials used
Each solar panel is made from aluminium, copper, glass and insulation.

The precise carbon footprint varies according to the source of the raw materials and the processing plants that turn the raw materials into finished material appropriate for manufacturing into solar panels.

Some aluminium processing plants use energy produced by coal or oil; others use hydroelectricity or nuclear power. The same applies to glass and copper.

Each source leaves a different carbon footprint so in our figures we have used average carbon emissions over the whole of each industry: –

  • Aluminium: We use aluminium for the panel trays and for the profiles which make up the frames. We calculate the aluminium we use in our solar panel and frame needs 442.6 kWh of energy to produce it.
  • Copper: We use copper for the meandering heat pipe and for the sensor pockets. We calculate the copper we use needs 108.4 kWh of energy to produce it.
  • Glass: We use special glass and this makes up most of the weight of each panel. The production of this glass uses around 100.9 kWh of energy.
  • Insulation: This uses around 19.4 kWh for each panel.
  • Selective Coating: our own specifically made selective coating needs around 45 kWh of energy to make it.
  • Additional material: we calculate that additional material uses 6.8 kWh of energy.
The total energy involved in sourcing and production of these materials: 723.1 kWh

Now that we have established this figure we need to look at the energy used in the manufacturing process of our solar panels.  When we combine these two figures we can calculate the carbon emissions involved in the production, from raw materials to finished

Talking about efficiency 
We try to keep the manufacturing process as efficient as possible.  This doesn’t mean costs are cut, in fact it is our continual investment in state of the art facilities for over 40 years that means we can offer such efficient and high performing solar panels.

One example of this is by employing our special folding technology, which lets us avoid techniques such as welding.

In this instance, the benefit is twofold; a no-weld single sheet box is far stronger than one with welds AND cost of energy is reduced.

Manufacturing a solar panel
The first part of this article talked about carbon footprints involved in sourcing materials.  This part talks about the manufacturing process and how much carbon is actually used in the construction.

Thermal Panel Production Press

It seems obvious that the manufacturing process would contribute to a carbon footprint; but just as all solar panels are not created equally, so too there is a need for concern when looking at other solar panels and the manufacture process behind them, and ultimately, what the REAL carbon savings will be.

This part of the article gives you the final, real world, cost (in carbon dioxide) to produce our solar panel, see “Talking about efficiency”.

Energy used:
We have managed to keep manufacturing energy costs to around 45 kWh per panel. Combining this figure with the energy used in the sourcing and processing of the raw materials we now know the overall energy usage per panel:

The overall energy usage per panel: 768.1 kWh

which translates into: 145.5 kg of carbon dioxide per panel (using normal energy mix assumptions)

How much carbon our solar panel system will save when used in a typical home in the UK.

Calculating the total carbon footprint:
In the UK, most homes employing a solar panel system, typically use a two panel system.  There are also other factors (travel for example) and components involved; such as pump stations, controller pressure vessel and piping -of which typically add 200 to 250 kilograms of CO2.  This means your default two panel solar system, installed, has left on average a carbon footprint of 600 kilograms.

Here, we will take a look at the three common water heating methods; a condensing boiler, oil (fossil fuel) and electric.Carbon “Payback”:
So the final carbon footprint is 600 kg.  This may sound a lot but we will soon learn this can be saved, or payed back in as little as a few months.  It all depends on what method the home i question uses to heat their hot water.

When solar displaces a condensing boiler: 
An average two panel system in the UK, where the system displaces gas burnt by a condensing boiler as the fossil fuel, a solar thermal panel system saves about 500 kilograms of carbon dioxide each year, so the solar panel system “pays” for itself in less than 15 months.

Carbon savings with Hot Solar Water:

When compared to a home using:                     Per year:              35 years:              Payback:

A condensing boiler:                                                500 kg                   16,900 kg             15 months

Oil as the fossil fuel:                                                 800 kg                   27,400 kg             9 months

Electricity to heat water:                                        1300 kg                   44,900 kg             5 months

Carbon Savings: 500 kilograms per year

Displacing fossil fuel

If the system displaces oil as the fossil fuel it will save around 800 kilograms of carbon dioxide each year, and will “pay for itself” in just nine months:

Displacing electric heating

Here the greatest savings are realised.  If the solar panel system displaces electricity it will save around 1300 kilograms of carbon dioxide in a year, “paying” for itself in about five months!

How those savings add up over the years

Your solar panels come with a 20 year warranty and a 35+ year life expectancy. Your investment will net you long term gains, both financially and environmentally.

Here is just how much carbon your 2 panel solar system would save a typically sized UK home over the next thirty five year lifetime, based on the current fossil fuel used for heating:

Hot Solar Water Solar Thermal In Roof Tile System Lancashire


  Natural Gas: 16,900 kilograms

  Oil: 27,400 kilograms

  Electricity: 44,900 kilograms


That is almost 44 and a half tonnes in CO2!



It is therefore clearly carbon effective to use Hot Solar Water solar systems. But that is not the end of it…

For example:
For every six tons of glass recycled one tonne of carbon dioxide can be saved.

The Carbon Footprint of a solar panel

Recyclable materials…
At the end of the 35 year life expectancy of our solar thermal panel system, virtually all of the materials can be recycled easily.

In particular, aluminium (a key material in our solar panels) is easy and cheap to recycle and there are many aluminium recycling plants; in the USA for example, aluminium cans are the product that is most recycled.

Similarly, copper and glass recycling is widely undertaken. Copper’s recycling value is so great that premium-grade scrap normally has about 85% of the value of the primary metal from newly mined ore.

The choice to use recyclable materials in our solar panels is not based on coincidence, and in some instances, it actually places a premium on our solar panels.  But for the continued carbon savings they offer beyond the lifetime of your solar panel and the performance qualities they can sustain over such a long lifetime we hope you will agree, that not all solar panels are made equal.