• April 9, 2014 - Domestic Renewable Heat Incentive Released - Solar Thermal has got the great government funding through the Domestic RHI which it deserves! Solartwin Solar Thermal panels have just become not only a cost cutting and very green option to heat your water but now you will receive additional... More →
  • November 6, 2013 - Notice to Solartwin customers - Letter's from Stenfield & Co - A number of Solar Twin Ltd customers have been in touch this week to query a letter they have received from legal firm Stenfield & Co. - The content relates to Solar Twin Ltd's liquidation, and claims that customers "undoubtedly paid more than... More →
  • July 12, 2013 - Renewable Heat Incentive Updated - Solar Thermal to have Heavy Support - The Government have today released the Renewable Heat Incentive: The first step to transforming the way we heat our homes. If you are looking to buy a SolarTwin System contact Genfit. "the scheme will be open to anyone in these groups who installed... More →
  • May 27, 2013 - DECC announce they are doubling the RHPP grant for solar thermal from £300 to £600 - Solar Thermal Panels Receive Huge Renewable Heat Premium Payment - Solar Thermal has received a huge boost, it's a great time to buy a Solartwin Product. - Greg Barker tweeted about the scheme - - Big uplift for #RHPP Vouchers to put a shot in the... More →
  • February 14, 2013 - Solartwin DIY reviews - SolarTwin Reviews from Reviewcentre - "Review Centre is a community of real people, just like you, sharing their product and service experiences. - Our community of reviewers are a passionate bunch who want to help you discover what's right for... More →
  • January 17, 2013 - Crackdown on aggresive solar selling - YouGen, a leading consumer body serving the renewable and energy efficiency sectors, is calling for a change in the law after a review by the Office of Fair Trading revealed unscrupulous selling tactics by solar and other energy efficiency... More →

Carbon Clawback in Solar Water Heating. Solar Parasistics. Coefficient of Performance: Energy & Carbon.

This is the data table which we were originally banned from publishing by the Solar Trade Association. I hope you enjoy reading it.

 Brand tested Technology type ENERGY Clawback %   (Mains pumped solar users PAY for this mains electricity, year after year: it averages about 80 units a year.)  CARBON Clawback %   (The environment may take a hit here.) Coefficient of ENERGY performance Coefficient of CARBON performance
AES  Mains Flat Plate  8%  19%  13x  5x
ZEN   Mains Flat Plate  4%  11%  22x  9x
Filsol   Mains Flat Plate  8%  20%  12x  5x
Energy Engineering   Mains Flat Plate 8%  21%  12x  5x
Fieldway   Mains Flat Plate  7%  19%  13x  5x
Thermomax   Mains Vaccy Tubes  9%  23%  11x  4x
Riomay   Mains Vaccy Tubes  10%  24%  10x 4x
Solartwin  PV pumped flat plates  0%  0% infinite   (the best) infinite   (the best)

Data from “Side By Side Testing of Eight Solar water Heating Systems” DTI/ETSU by Martin and Watson, 2001. with “Split Water Runoff Scenario” using the 2.5 gas to electric carbon intensity weighting quoted in the report. For more about this report take a look at this video.

Who did the three main solar thermal technologies compare?

  • Flat plates averaged 7% energy clawback and 18% carbon clawback.
  • Evacuated tubes were even worse. They averaged 9% energy clawback and 23% carbon clawback.
  • Solartwin had zero energy clawback and zero carbon clawback in its operation, proving that this simple technology is the least environmentally damaging, on the basis of there two important measures.

Clearly the carbon clawback of solar water heating can be reduced.

Five ways to reduce the levels of carbon clawback in solar water heating systems include:

  1. Not choosing indirect evacuated tubes. It appears from the data that solar heating systems based on tubes are the least sustainable because they need stronger and more energy-thirsty pumps, perhaps because these sensitive technologies have rather small heat exchangers at the top of the tubes to remove heat from. So the fluid must rush past them as fast as possible.
  2. Choosing more efficient pumps or lower powered pumps which simply consume less energy. It is notable that Zen (an import) was already doing this by the time of the study but the other, mainly UK made, systems seemed to be stuck in a timewarp. Ask your solar supplier if they use low power pumps. We, and a number of other solar heating suppliers do this.
  3. Choosing variable speed pumps (flow modulating pumps) which drop their speed and power consumption at lower light levels or lower temperature differentials. Ask your solar supplier if they use modulating pumps. We, and a number of other solar heating suppliers do this.
  4. Choosing water as a heat transfer fluid. This is 6 times less viscous (gloopy) than “normal” antifreeze so it requires less energy to pump. We, and a few other solar heating suppliers use water.
  5. Choosing PV pumping. This gets rid of the nasty parasitics altogether. Again, this is what Solartwin does: cleaning up its operational environmental footprint. Which solar heater will you buy? Low carbon operation or Zero carbon operation

It’s a great feeling to be free to publish this table!

We were ordered not publish brand by brand comparisons by the STA when we originally tried to do so (most board member companies at the time were suppliers of the tested systems). Then for good measure and presumably to show who was not top dog we were fined £1000 by the STA for resisting their censorship.

What you are reading are hard-won secrets: rights to disclose consumer-oriented information which (like Legionella safety) the solar thermal industry has sought to conceal using a ruthless campaign of exclusion, threats and coercion against whistleblowers.

It is hoped that the Energy Saving Trust report on solar water heating (publication expected later in 2011) will show that the solar thermal industry has improved dramatically on these figures and this it it trying to move on from its concealed but polluting past. The STA’s Chairman, Howard Johns,  even claimed that mains pumped systems were zero carbon until they were told not to do so by the ASA. One hopes that the rumoured pullout from the trials before it ended, by at least one evacuated tube supplier, was not linked in any way whatever to its emerging parasitics figures.

Should a minimum CoP (energy) of, say, at least 20 apply to state subsidised solar thermal systems? This kind of approach already happens for heat pumps.

I hope this is interesting. Feel free to tell your friends.

For speed, and for the sake of the environment, Solartwin offer feasibility checks and fixed price solar quotes by phone.
Unique in the world, Solartwin's phone survey now also uses online aerial photographs of your roof in most urban areas!

Unlike most solar surveys, our instant surveys and quotes are completely free and with no obligation.
Click here to request a survey

Or Call us on

0344 567 9032

Domestic Renewable Heat Incentive Released

Solar Thermal has got the great government funding through the Domestic RHI which it deserves! Solartwin Solar Thermal panels have just become not only a cost cutting and very green option to heat your water but now you will receive additional funding too! The Domestic RHI rates – Released April 2014 Ofgem have produced a […]

Read More | Archives

Notice to Solartwin customers – Letter’s from Stenfield & Co

A number of Solar Twin Ltd customers have been in touch this week to query a letter they have received from legal firm Stenfield & Co. The content relates to Solar Twin Ltd’s liquidation, and claims that customers “undoubtedly paid more than you should have and it is highly likely that you will have been […]

Read More | Archives

Renewable Heat Incentive Updated – Solar Thermal to have Heavy Support

The Government have today released the Renewable Heat Incentive: The first step to transforming the way we heat our homes. If you are looking to buy a SolarTwin System contact Genfit. “the scheme will be open to anyone in these groups who installed an eligible technology since 15th July 2009” so if you have a […]

Read More | Archives

DECC announce they are doubling the RHPP grant for solar thermal from £300 to £600

Solar Thermal Panels Receive Huge Renewable Heat Premium Payment Solar Thermal has received a huge boost, it’s a great time to buy a Solartwin Product. Greg Barker tweeted about the scheme – Big uplift for #RHPP Vouchers to put a shot in the arm of the market ahead of full Domestic #RHI tinyurl.com/ktxz3o2 — Greg […]

Read More | Archives

Solartwin DIY reviews

SolarTwin Reviews from Reviewcentre “Review Centre is a community of real people, just like you, sharing their product and service experiences. Our community of reviewers are a passionate bunch who want to help you discover what’s right for you.” (Review Centre) We are well rated on review centre, this shows the excellent product quality of […]

Read More | Archives


or jump to...