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Renewable heat soon to join the energy revolution

Posted by Gabriel Wondrausch on 6 November 2009 at 9:13 am

Until a few months ago, solar thermal hot water heating has been the most cost effective way for people to generate their own renewable energy - for every pound invested it has usually delivered the highest units of energy.

The reason for this is that solar thermal systems have always been the most efficient renewable energy systems. Solar thermal hot water systems directly convert the sun's infra-red radiation into heat. No other energy is needed apart from a small pump and there are no processes that reduce efficiency such as those involved in generating electricity from the sun.

However, in the last few months this has all changed with the proposed introduction of the feed-in tariff in April 2010. It will dramatically increase the use of renewable energy by providing a long term financial incentive for people to invest in generating renewable electricity.

Initially, the feed-in tariff will pay a higher amount for electricity generated than for heat. Although a solar thermal system produces more Kwh/£, the feed-in tariff effectively makes a solar PV system a better financial option as the energy produced by a PV system is worth more.

But not for long. The situation will change again in April 2011, when the government introduces the renewable heat incentive (RHI). The RHI is a ground breaking strategy to increase the uptake of renewable heat in the UK.

Heat is a huge part of household energy consumption and accounts for nearly half of Europe’s total energy demand. Until now this has been largely overlooked. We don't know yet how the RHI will be implemented or how the payments will be figured. We do know that all systems installed since 15 July 2009 will be eligible for the RHI.

Currently, the Renewable Energy Association is predicting that the RHI will pay about 16p per kw for heat generated by solar thermal systems.

It is clear that we are on the verge of a renewable energy revolution. Until now the biggest barrier for people wanting to generate their own renewable energy has been the up-front capital cost. With the introduction of the feed-in tariff and the renewable heat incentive the government is making renewable energy available to everyone.

Photo by maistora

About the author: Gabriel Wondrausch is founder and director of SunGift Solar, which installs solar thermal and other renewable energy systems in the South West of England.

If you have a question about anything in the above blog, please ask it in the comments section below.

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4 comments - read them below or add one


banjaxComment left on: 9 June 2012 at 11:38 am


I find your thermal innovations very interesting. In particular deserving of their own story here or on youtube.  

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Jayhawk International Ltd

Jayhawk International LtdComment left on: 20 March 2010 at 1:54 pm

Barry, what we as a solar thermal small innovation industry has to do before thousands of home owners covered their roof in PV which becouse its only 16% efficent needs 10m2 of space per 1,000 watts. Then becouse its grid tied, 7% is lost in transmission, which nobody talks about.

In my paper I used £0.4p for mains gas use, which when you look at the huge heat benifits I gain in my own home with 44 tubes, now almost doubling them, the drop in gas use in winter is substantial as you are keeping the house warm all through the day unlike now where its allowed to go cold.

This winter demonstrated how close we are to shortages of gas, but without electricty to run a pump, the gas supply means nothing.

My integrated system provides back up to all the circulating pumps in order to continue to run during a power cut which is more possible that gas shut offs for homes.

Even though a home owner can claim £0.43p for genarating electricity while 60% of a homes energy is in heating, 23% in hot water when using mains gas, it makes more sence to invest in my type of new system, perfect for code 4 new homes, but the benifit is the existing housing market for those looking to gut the place and replace everything, as changing the boiler only and adding on some solar panels is not worth the effort, as its the radiators and uninsulted copper pipes everywhere thats the big heat cost lost.

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Jayhawk International Ltd

Jayhawk International LtdComment left on: 20 March 2010 at 1:45 pm

Hi Gabriel and Barry, I hope I can share with you and others my experiances from using my home in Wimborne, Dorset where I have installed all the micro renewable energy technologies 11 years ago including the best of the all as a pay back, rain water harvesting.

I began designing solar thermal collectors in 1992, prior to that I developed a thermal store which would deliver heating and hot water from a single tank.

At Eco Build I show cased for the first time my waterless heat pipe radiators haveing designed and developed 3 years ago with around 200 installed between the USA and the UK, a super heat pipe evacuated tube collector now approved for the RHI and Tax breaks in the USA of up to 30%.

For the past 4 years, since I changed my tubes over from Sunda to Apricus, linked the 44 heat pipes direct into my 250 litre thermal store which is connected via a circulating pump to my tradiational steel water filled radiators (thats the weakness in the system). My wall mounted gas boiler works indepedant to the central heating, as its sole job, no stress is to back up the solar thermal side.

My up dated Sorel controller I installed 2 years ago which monitors the energy savings in Kwh reads 33,760.00kWh, as unlike the new entrants into solar thermal, the gas boiler industry and comodity traders who offer a solar hot water only system, which within the RHI scheme will pay out around £400.00 a year, while my new solar/gasboiler central heating package including new A rated gas boiler, 10 heat pipe radiators, 300 litre thermal store, 80 tube heat pipes and all the fittings will be offered out at just under £10,000 + VAT.

In other words a system package that works, its simple and bypasses the incumbant plumbers merchants and the gas boiler industry as they have no understanding on how to incorparate solar thermal heat into a central heating system.

The numbers.

In my 3 page paper, it shows the returns possible from 1,000 watts of PV installed which takes up 10m2 of a roof space.

Using the same 10m2 as an area for my Suntech or Apricus collectors, the output in kWh at peak times of the day same for PV works out at 7,200 watts as against 1,000 watts for PV

Installing a completly new central heating system as thats the only way to benifit from solar thermal heat, the pay out where I used just 4 hrs a day for 365 days a year, same for PV was £1,245.00 + around £250.00 in energy savings, all tax free for 20 years.

The figures for PV was £545.00 a year

Contact me on for the information

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Barry Nutley

Barry Nutley from Viridis Energie ConsultantsComment left on: 6 November 2009 at 10:20 pm

Hi Gabriel. You suggest that solar thermal has been the most cost effective way to generate renewable energy? Could you put some math to that? IE what would the "typical" annual saving in £'s be for the "average" 4 person home be, if heated by gas (let's say 4p/unit), what size system would be required (let's assume a 200ltr cylinder with a south facing roof), and what sort of cost for installation? 


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