Picking Through The Wreckage of Zero Carbon Homes

The policy that categorically does not do what it says on the tin

It all started out so well in those early years.  There was a sense of shared endeavour in the construction industry.  When, in 2006, the government announced that by 2016 all homes built in the UK would have zero net carbon emissions, no one thought it would be easy, but many in the industry were eager to rise to this inspirational challenge.

The concept was that we should stop building new homes that would only need to be upgraded later to be properly energy efficient. Building these homes fit for the future would stimulate a mass-market for energy efficiency measures and renewable energy technologies and result in tradespeople and designers developing skills that could be carried over into the upgrade of our existing stock of buildings.

Well, here we are in 2014 and how has it fared?

In the run up to the Queen’s Speech, Stephen Williams, a Liberal Democrat MP and minister at the Department of Communities and Local Government (DCLG), began briefing via the Lib Dem website that he’d ‘saved’ the Zero Carbon Homes (ZCH) policy from those nasty Tories.

From information in his article its possible to piece together how ZCH will work.  So let's peer through the smoke drifting around and have a look at the train wreck we’re left with.

It seems like all housing developers will have to build homes that are equivalent to the Code for Sustainable Homes level 4, which is only a 44% improvement on the so-called regulated carbon emissions of a 2006 home.

However, even this overstates the ‘achievement’.  As I have covered before in this blog, the definition of zero has been adjusted to include only regulated carbon emissions (those from heating and hard-wired lighting).  All energy used by plug in electrical appliances (white goods, gadgets, audio-visual) have been removed from consideration.

Add back in the average emissions from plug in electrical appliances and the picture is even less flattering.  The original vision of Zero Carbon Homes has been diluted to such an extent that the achievement of which Stephen Williams is so proud is that a home built in 2016 will be allowed to produce fully 71% of the carbon emissions of a home built in 2006.

The average energy bill for one of these ‘Zero Carbon’ homes will be similarly unimpressive.  I calculate that a 3 bed semi-detached ‘Zero Carbon’ home would have a combined energy bill of £800/year whereas one built to 2006 standards would have a combined energy bill of £1080/year.

The political sleight of hand that Mr Williams is using to justify his hyperbole was announced in the Queen’s Speech and is the creation of legislation to enable an element of ZCH called ‘Allowable Solutions’.   This could be better called ‘Buying Carbon Offsets’ because it means that instead of pushing the performance of the building itself from Code level 4 to Code level 5 (zero regulated carbon emissions), the developer can choose instead to pay into a government-managed fund.  What this fund will be used for is, as yet, undefined, but seems likely to be spent on upgrading existing buildings.

Allowable Solutions was first proposed as a means of helping more challenging homes (for example flats with limited roof area) make it over the line by allowing carbon offsetting for that difficult last little bit.  What was supposed to be the mint chocolate with the coffees has now become the main course of the meal, potentially accounting for 56% of the regulated emissions.

The circularity of this is mind-bending.  Instead of building efficient homes in the first place, we effectively collect a tax from the developer, leaving the house-buyer with largely unchanged energy bills and putting the money into a pot which may or may not at some unspecified future point be used to improve existing buildings.

The opportunities for double-counting the benefits are also clear.  It's hard to imagine ministers avoiding the temptation to take credit for both the new homes being zero carbon and for whatever measures the fund is spent on at the same time.

Furthermore, there is to be a provision for ‘small developments’ to be exempt from reaching Code 5.  Again, it is not yet clear what small means in this context, but Barbour ABI has estimated that if small means a development of 10 or more homes then around 10% of new homes would be exempted from the policy, whereas if developments of up to 50 homes were to be considered small, then this figure would be around a third of new homes.

Which Tin?

In his article, Stephen Williams says that Zero Carbon Homes “does exactly what it says on the tin”

This astonishing claim doesn’t even get close to passing the ‘reasonable person’ test.  Someone offered a home described as Zero Carbon would have a reasonable expectation that the carbon emissions from the home would be zero and energy bills would be extremely low.

After ten years of backtracking, what we’ve actually got is a policy where new homes will produce more than 70% of the emissions they started with, coupled to a carbon-tax that might apply to only 2/3 of new homes built, and energy bills for the house-holder reduced by only 30%.

This policy "does exactly what it says on the tin" only as long as the tin in question is labelled "Business as Usual for Property Developers"

DCLG has succumbed to the enticingly simple argument that a proper ZCH policy would impose higher costs on developers and slow the rate of new build, thus threatening the economic recovery. The reason this argument is bogus is that if build costs rise, then the price a property developer would be willing to pay for land will drop.  Building to higher standards simply reduces the wind-fall to the land owner.  The only time the burden of building to a higher performance falls to developers is when they have speculated that legislation will be watered down and over-paid for their land bank.

It is not clear that this “world-leading” policy even meets the wooly definition of the European Directive on the Energy Performance of Buildings that the UK must comply with by 2020.  This requires all housing to be ‘nearly zero carbon’.  It may be that this is tested in the European Commission, indeed a number of renewable energy associations are already considering just such a move.

All is not Lost

A properly designed structure for the Allowable Solutions might just get this train back on the rails.  The price per tonne of carbon should be set to encourage the use of now common on-site measures such as higher levels of thermal insulation, heat pumps, solar water heating and solar PV.

One opportunity would be to set the price per tonne in a tiered structure, with an increasing marginal cost.

Code 4 is a 44% reduction in the emissions compared to a 2006 home, leaving 56% emissions available to offset under Allowable Solutions.  What if the chunk from 44% to 72% was priced at £120 a tonne, and the chunk between 72% and 100% was priced at £30 a tonne. Developers would have a strong incentive to drive efficiency up towards the 72% level (broadly equivalent to the old 'carbon compliance' level) using improvements to the building.

A developer who built to business as usual (Code 4) and paid the entire carbon offset would have an average cost to bear of £75/tonne.  By contrast a developer that improved insulation levels or installed renewable energy on the homes to bring down emissions below 28% of 2006 levels could reduce their average cost of carbon offsets down to £30/tonne.

A policy designed like this would be responsive to a changing market. If the housing market continued to improve and government decided that landowners could bear more of the costs of the policy, then the relative width of the bands could be adjusted.

Come on Mr Williams, all is not yet lost. You've still got time to make the reality of Zero Carbon Homes match your rhetoric.

Slow Burner - how will the Domestic RHI Take off?

How much can the first year of the Feed in Tariff tell us about uptake for the Domestic RHI

How it went for the Feed in Tariff

A number of people (including the solarblogger himself) tried to temper expectations for the domestic RHI with the argument that the Feed in Tariff (FIT) took a bit of time to get going. The logic goes that it takes time for the public to become aware, for installers to work out how to market it, and especially for housing associations to get organised. 

I thought I'd take a look at the numbers to check whether they supported this idea. 

I wanted to compare the take up of PV in domestic installations before and after the introduction of the FIT. There is a wealth of data available from the Department of Energy and Climate Change (DECC) on the levels of PV deployment  under the FIT, but much less for the years preceding it. I relied upon this report on the Low Carbon Building Programme (LCBP) to build a picture of deployment rates before the FIT. 

Under LCBP phase 1 (the domestic stream) there were 4,428 installations of PV. The average size was 2.18kWp, for a total capacity installed under the scheme of 9.7MWp. 

Since the report doesn't disclose the deployment in each period, I estimated PV deployment based on overall scheme expenditure.  I then combined this with FIT data for systems below 4kWp, most of which is likely to be domestic. 

The results are very interesting. 

When you look at the plot of the overall data, it sure does seem that all the action started in year two of the scheme. But this is a trick of exponential growth. Look at the lower plot, where I have shown the data only up to the end of year one. The first year was spectacular. 

The level of deployment grew from round 700 installations a quarter before the FIT to 11,000 a quarter at the end of the first year. Before the FIT subsidy, solar thermal systems were being installed at a rate around 10 times higher than solar PV. By the end of the first year, solar thermal had declined slightly, but solar PV installations outnumbered them by almost double. 

And so to the Domestic Renewable Heat Incentive

There are a number of reasons why the domestic Renewable Heat Incentive won't take off like the Feed in Tariff did. 

1.  The Feed in Tariff.  

When the FIT was launched it was the only show in town. The grant scheme for renewable heat was derisory by comparison. As the domestic RHI launches, people interested in investing in their homes to reduce energy bills have the choice of both FIT and (I suppose) the Green Deal. 

2.  Installation complexity. 

With the exception of solar thermal, all the domestic RHI technologies replace an existing heating system, rather than being an add-on. People will be more cautious about installing a new technology when they worry that the impact of it not working is a cold house and no hot water.

Renewable heating installations are generally more intrusive too. A heat pump may require the replacement of radiators to cope with lower heating temperatures, biomass boilers can require a lot of space. New products such as this one which simplifies the installation of solar thermal to levels approaching that for solar PV may help overcome this barrier, at least for solar thermal where there's always the backup heater. 

3. Off Grid Target Market

The domestic RHI tariff levels were intended to stimulate a market in the 20% of homes that are off the gas grid. For sure, the returns are better when heating with oil or electricity, but returns for solar thermal on gas can also be good, as this analysis has shown. 

4. World First

The UK feed in Tariff followed the implementation of similar schemes in other european countries. Businesses could see the rapid take up of markets that had resulted and anticipating a similar trajectory for the UK, were pumped and ready once the scheme launched. By contrast the RHI this a genuine worlds first. There's no equivalent to look at to predict uptake. The many, many false starts for the scheme also didn't help. Many installation companies I spoke to weren't even willing to spend time thinking about it until they were absolutely sure it had launched. 

5. The Feed in Tariff (again)

My final reason is perhaps the most important. The way the government managed the Feed in Tariff has led to the widespread belief that as soon as any renewable energy scheme is successful it will be ruthlessly hacked back. The shadow that the treatment of the FIT scheme casts is long and pervasive. 

For all this, the scheme offers a level of financial support beyond anything that renewable heating technologies have benefitted from before. My plea to the industry is to give it a while before judging the success or otherwise of the scheme. 

It may take time to take some time to warm up, but warm up it surely will.  

The Domestic RHI and Solar Thermal Stores

The Law of Unintended Consequences Strikes Again

The domestic RHI was structured with the intent that the complementary combination of solar thermal with other heating technologies would be actively encouraged by receiving double subsidy for the domestic hot water energy.  Unfortunately, the wording of the legislation has prevented installers using the simplest way to implement a combined system (the thermal store) because it rules out solar systems that can make even a theoretical contribution to space heating.

Thermal Stores in Hot Water

Solar thermal systems can make a contribution to space heating as well as domestic hot water (DHW) preparation, especially in spring and autumn where the days are still bright and there is a demand for space heating.  These systems are not yet as common in the UK as those for domestic hot water, but in more developed European markets such as Germany and Austria, so-called "solar combi systems" are popular.

In a thermal store the domestic hot water is heated in a heat exchanger
and the contents of the store pumped around the space heating circuit

A good way to combine solar thermal with space heating is to use a thermal store, essentially a large (typically 500 litre minimum to 1,000 litre) hot water cylinder with heat inputs from both solar and the backup heating system and with outputs to domestic hot water and space heating.  Typically the body of water in the thermal store is heating system fluid (primary water) and domestic hot water is heated on-demand in a heat exchanger as it flows to the hot tap.

Both heat pumps and biomass heaters operate well when running continuously rather than cycling on and off, so charging a thermal store is a good technical solution that improves the overall efficiency of the heat pump or biomass boiler.

Where the designer is seeking for the solar to make a reasonable contribution to the space heating, the solar panel array installed is large (around 12-18 m² for a domestic property).   The coverage of domestic hot water of such systems can be very high, 70% and above.

Where the designer is aiming for solar to mainly cover domestic hot water the panel array is smaller (typically in the range of 3  - 6 m²).  In this case there is still a theoretical possibility that the solar energy will contribute to the space heating, though in practice the system is sized with the aim of supplying 60-70% of water heating.

The current domestic RHI legislation completely excludes systems that can contribute towards space heating.  

The text in the RHI regulations defines an eligible solar system as follows:

a)     is designed and installed to provide heating solely to a single eligible property and solely for an eligible purpose using liquid as a medium for delivering that heat;

(b) meets the requirements set out in whichever of the standards for solar thermal plants specified in paragraph 1(5)(a) and (b)“eligible purpose” means, in relation to heat generated by— […](b) a solar thermal plant, the purpose of domestic hot water heating for an eligible property;

An implementation of solar where there is even a theoretical possibility of the solar contributing towards space heating is completely excluded from the scheme.

The reasoning behind ruling out solar space heating was that the domestic RHI is “deemed” – the solar energy is not measured, instead it is estimated using an approved calculation and the calculation only works for domestic hot water.

However, by ruling out any solar installation that does not solely heat domestic hot water, the domestic RHI has made the combination of complementary renewable heating technologies such as solar and heat pumps less likely. Solar thermal has lower associated carbon emissions than any form of back up heater, so every unit of solar thermal heat that can be used, whether for space heating or domestic hot water reduces carbon emissions.

Configurations where the solar is offsetting a proportion of fossil fuel space heating are also disincentivised by their complete exclusion from the domestic RHI.

When installing biomass or heat pumps with a thermal store, the additional cost to add a solar coil into the store is very low, making the marginal cost of adding solar thermal more attractive.  The domestic RHI would provide greater value for money if it encouraged, rather than discouraged such systems.

So how could the domestic RHI be changed to include solar space heating?

Two Suggestions

Two options occur, though I’d be pleased to hear of any other suggestions (please use the comments section).

First, it would clearly be possible to use a heat meter to measure the solar input into the thermal store.  Solar space heating systems cost more than solar systems aimed only at domestic hot water.  A requirement to fit a heat meter would be a relatively smaller proportion of the total installed cost and energy benefits, and houses that can fit large thermal stores are relatively thin on the ground, so it wouldn’t be too much of a cost for the scheme administrators to deal with the meter readings.

A second approach would be to allow space heating systems onto the scheme but to give RHI payments only for the domestic hot water energy provided, and calculate this with the current deeming method.  I’ve looked at this with the help of two years'  of data from a solar space heating system provided by Geoff Miller of GreenLincs Energy.  Simulations have also confirmed that the solar energy generated by a system providing solar space heating and domestic hot water is always higher than the same sized system targeted at only domestic hot water.  The RHI wouldn't be over-paying for solar heat.

The best outcome would be for it to be the choice of the homeowner whether or not to go to the expense and hassle of having a heat meter.  If they wanted the extra payments for space heating, then they would need to install a heat meter, otherwise they could claim for only the solar heat in their domestic hot water.

This has formed the basis of a proposal submitted to the Department of Energy and Climate Change (DECC) yesterday outlining how the scheme could be improved by allowing solar space heating.

The 100% Solar Powered National Grid?

Image: Viridian Solar

Is your Car the Star?

I was intrigued by a recent article in the Telegraph (of all places)  in which the writer predicted that solar will dominate global energy production.

The article extrapolated the falling costs of solar photovoltaic generation in recent years and combined this with a whistle-stop tour of technical innovations in the sector - perovskite solar cells, flow battery technology  and robotic cleaning of panels in solar farms.

The article predicted the end of the fossil-fuel era, and concluded that wind turbines would at best be a regional niche technology because their costs were static by comparison with the enormous technological strides that will continue to be made in solar.

As is common in such articles, the intermittent availability of solar power was mentioned only in passing along with the solution – energy storage technologies.

The article made me wonder about energy storage.  How much energy storage would be needed if solar were to win the race for global dominance of energy production?  Is it a realistic prospect? 

Solar power production is intermittent in three ways.  First there is the unpredictability of cloud cover and light levels during the daytime.  Second there is the more predictable effect of the sun travelling across the sky during the day and disappearing at night.  Finally there are the seasonal variations in day length and clear skies from summer through to winter.

One Helluva Battery

Let’s do some simple analysis to try to quantify the challenge.  To keep things simple, lets take a look at the following question:

‘How much energy storage would be required to hold the electricity generated during daylight hours for use overnight?”

The graph shows the half-hourly electricity demand from the UK national grid for 23rd April 2013.  I chose a day that was pretty sunny, but in spring rather than summer or winter.  The total electricity consumption that day was around 826,000 MWh.

On the same day in April 2013, the 44.5 kWp south-facing PV array on the roof of Viridian Solar’s factory and headquarters in Cambridge produced 233 kWh, or 0.233 MWh.

If we were to scale up the PV array to produce the same number of units of electricity as the UK demand that day, it would be:

44.5 x 826,000 / 0.233 = 158,000 MWp or 158 GWp

To put this figure in context, the UK government central forecast predicts installation totalling 10 GWp within a decade in its solar strategy, however the UK installed 1.1GWp in the first quarter of 2013.

If progress continues in the reduction of costs of solar modules, then it’s not so impossible to imagine that the deployment of this level of capacity over the coming decades might happen.

I've scaled up the output curve from the Viridian Solar PV array for that day as if it were 158 GWp and added it to the graph to show the timing of solar power generation compared to the timing of electricity demand.

The energy storage required for the solar output to keep the country going through the evening, night and until the solar output exceeded the demand the next morning would be 428,000 MWh or 428 GWh.

By using the current level of electricity demand we’ve ignored the possibility that energy efficiency gains might reduce total electricity demand significantly and thus drive down the amount of energy storage we would need. 

We've also ignored the new technologies emerging that intelligently move the timing of electricity use for applications that are not time critical (such as running air conditioning and refrigeration).  Such technology could change the demand curve to better fit the solar output, also reducing the amount of storage required.

However, some 40% of our energy use today is for heating and currently most of this does not use electricity but instead burns gas and oil.  This massive demand for energy will also need to be de-carbonised and it seems likely that it will require electricity to operate heat pumps.  Clearly heating demand can be reduced with better thermal insulation and solar heating panels on our buildings, but it seems that we’ll be doing well if we can hold our electricity demand flat relative to current levels.

So what does 428,000 MWh mean in the real world?

Consider Dinorwig pumped storage power station.  This massive civil engineering endeavour in Snowdonia National Park comprises 16km of tunnels, 1 million tonnes of concrete and 4,500 tonnes of steel. The turbine hall is Europe’s largest man-made cavern.  Cheap night-time electricity powers reversible turbines to pump water from a lower reservoir at the bottom of the mountain to a reservoir higher up the mountain.  At times of peak demand the water is allowed to run back down through the turbines and generates electricity.

It cost £425m, took ten years to build and was completed in 1984, that works out to around £2bn in today’s money.

It has a power output of 1,728 MW for six hours, a total of 8,640 MWh.

We’d need to build another 48 of these babies to store solar PV electricity through a 24-hour period to meet demand.  Assuming sites could be found, and that their costs were similar to Dinorwig, then the bill looks like it would be a cool £100bn.  That’s a very big number indeed, equivalent to around 2.5 times the estimated cost of the HS2 rail line.

 

EVs for PVs

But maybe there’s a cheaper way.  Maybe the answer to the intermittent nature of renewable energy is sitting in driveways and garages all over the country.

Would it be possible to use the batteries of electric vehicles to store energy from times of excess generation and release it at times of need?  What do the numbers look like?

One of the main thrusts of electric vehicle development is battery storage.  The challenge is that although most vehicles are used for relatively short journeys most of the time, occasionally we like to go away to visit family or friends further afield.  We want our vehicles to have enough range to cover these infrequent long journeys.

Here’s the capacity and estimated range of a few of the electric vehicles currently on sale.

Source: http://www.fueleconomy.gov/feg/evsbs.shtml

Most manufacturers have settled on a battery size around 25kWh as the right compromise on range and cost.  It seems likely that for mass adoption the manufacturers will need to develop vehicles with higher ranges.  However, let’s use 25kWh as a median value for the battery size in a car.

The annual average mileage for a car in the UK is 8,200 miles, or 22.5 miles/day.

Taking the average miles/kWh from the table means that to meet the average mileage a battery of only 6.3kWh is required.  On most days, the car has 19kWh of excess capacity that is only needed for those unusual, longer journeys.  If, through smart metering and information technology, this excess storage could be made available (perhaps yielding a small income to the car owner), how much storage could it provide?

There were 29.1million cars on the road in the UK in 2013.

If we assume that the entire UK car fleet changes over to electric vehicles then the excess battery storage this would represent is 515,000 MWh, higher than the amount that I calculated would be needed to spread PV generation out through a 24-hour period.

Hold on a Minute

Before we get too carried away, there are holes in this rosy picture of the future that need to be mentioned. 

We’ve only thought about storing energy from one (sunny) day to the next, but we need to solve the problem of having energy available in winter too, or on days where the sunlight is lower. 

One option is to install a massive excess of solar PV – many times more to meet demand in winter, 90% of which would then be idle on sunny days.  Solar panel prices would have to drop spectacularly to make this approach viable.

Another concept, popularised by the Desertec Foundation is to locate the solar panels in a place where it’s sunny more of the time and day length doesn't vary so much.  We then build low-loss power cables to connect from the desert to population centres.
 
It seems to me that wind, wave and tidal power generation will have a prominent role to play, due to their complementarity to solar – the wind still blows at night and average wind speeds are higher in winter.

Whatever the future holds, its clear that energy storage has a significant part to play, and how ironic if the car, which did so much to drive the development of the global petrochemical industry, will play a central role in bringing our reliance on fossil fuels to an end. 

 

Merton Rule Lives on

Housing Standards Review Steps Back from Brink

Image: Viridian Solar

The Department for Communities and Local Government (DCLG) has concluded its Housing Standards Review and contrary to expectations the so-called Merton Rule, whereby Local Authorities can specify that new homes generate a certain portion of their energy use from renewable sources is retained.

 Part of the government's 'Red Tape Challenge', the Housing Standards Review (HSR) was wide-ranging and covered issues from wheelchair access in new homes, their consumption of water and use of energy.  The starting point of the review was that there has been a proliferation of different standards and that this is costly for both housing developers comply with and for Local Authorities to police.  DCLG proposed a number of ways in which it might simplify matters.

The consultation published in the autumn contained a serious threat to the deployment of renewable energy in new homes.   (See my earlier blog and infographic). 

After a series of changes in which the energy efficiency of new homes improved rapidly, progress has completely stalled since the coalition government came into power.  As a result, current building regulations can easily be met without renewables.  The only driver to encourage developers to use renewables in new homes is that many Local Authorities require it as a planning condition (often called the ‘Merton Rule’ after the first Authority to pilot the idea).  They can do this because they were granted the power in the Planning and Energy Act 2008.

Many Local Authorities have adopted planning policies like this as part of their Local Plans with the goal of creating local skills and supply chains, mainstreaming renewables and encouraging their wider adoption.

The HSR consultation document proposed to remove this power, potentially leaving renewable energy in new homes out in the cold until the building regulations reach 'Zero Carbon' and this feeds through into actual projects – potentially as late as 2022.

The Impact Assessment that accompanied the HSR consultation gave a clear indication of what was influencing DCLG’s thinking.  The anticipated ‘savings to industry’ only counted the reduction in the costs of housing developers.  The business lost by the renewable energy industry was not considered, and nor were the savings on energy bills for the householders. 

 Housing developers were offering a narrative that was both simple and attractive to the politicians:

 "Free us from these unnecessary costs and we'll build a way out of this recession."

It was very clear who was in the driving seat.

As the civil servants at DCLG worked their way through the responses to the consultation and pondered their conclusions the country was gripped first by a debate on the affordability of energy bills and then by endless rain, flooding in Somerset and politicians in wellington boots trying to outdo one other on how serious they consider the threat of climate change.

Was it these events that influenced the outcome – the idea that DCLG could find itself ordering underwater Local Authorities in Somerset to tear up their climate change policies? 

Or perhaps the rash of record profit growth announcements by house-building companies undermined the argument that costs had to be cut to get Britain building again?

Or maybe it was the work done by the Solar Trade Association and Renewable Energy Association to present the arguments for including renewable energy as houses are built?  (Step forward Mike Landy and Leonie Greene).

 Who knows what the decisive factors were, but on Thursday 13th March, the decision was announced and the Merton Rule lives to fight another day.

Untangling the Announcement

The way the decision was announced has caused some confusion, especially because the Written Ministerial Statement said that there would be no optional additional local standards:

This caused a number of sources to wrongly report that the Merton Rule had gone.  A bit of digging shows that the opposite is true.  The new rules are to be enacted through the Deregulation Bill.  Here's the relevant section:

To understand the impact of the changes, you need to read it with the Planning and Energy Act 2008, shown below:

So it can be seen that the change only affects Section 1(1)(c), and prevents Local Authorities in England (only) from requiring energy efficiency standards higher than building regulations for houses (only).  Crucially for renewable energy sections (a) and (b) are left intact and Local Authorities can continue with planning conditions that require a proportion of energy from renewables providing a critical bridge to Zero Carbon Homes.

Attention now turns to the definition of Zero Carbon Homes, encouraging DCLG to deliver it on time and how much of the standard can be 'bought-in' rather than 'built in' through a process called 'Allowable Solutions'.



Infographic - Slow Progress on Low Energy Housing in UK

Replace or Refurbish?

What to do with older solar heating systems 

It could be so much better



I've been getting correspondence from solar installation businesses asking what the domestic RHI might mean for older solar systems, specifically ones that were never entered onto the Microgeneration Certification Scheme (MCS) when installed.  Is there any way for these to claim the Domestic Renewable Heat Incentive (RHI)?

Can you just inspect that the solar heating system is compliant with the current MCS scheme, re-commission it and register it as if you've just installed it?

Do you have to rip it out and put in a whole new one?  Would even this be allowed on the scheme?

Setting aside the fact that the intent of the dRHI was to stimulate new installations of renewable heating, and that finding a way to register an existing (and potentially working) system is not really in the spirit of things, let's have a look at the regulations and see what they have to say about it. 

MCS

A review of the MCS standards (MIS3001 and MCS 004) finds that they are silent on whether the equipment used when installing a solar system must be brand new to be registered with the scheme. The implication is therefore that an installer could go through the standard line by line to ensure that the existing installation is compliant, making changes to components as required and registering the system on the MCS database.  In effect the installer is building a system from ‘second hand’ parts, some of which happen to already be on site and fixed in place.

However, just getting MCS registered does not mean you can get the domestic RHI.  It's also necessary to comply with the eligibility requirements of the RHI scheme itself.

Domestic RHI

The domestic RHI legislation has now been laid in parliament, so it’s possible to see the basis that OFGEM will be using to create the scheme rules.

The relevant section of the domestic RHI regulations is on page 12 in section 9:

Plants used to generate heat before the first commissioning date9.—(1) The requirements referred to in regulation 3(b) are that no part of the plant which generates heat, other than any of the components listed in paragraph (2), was used before the plant’s first commissioning date.(2) The components referred to in paragraph (1) are—(a) immersion heaters and other components which solely generate heat for the purpose of heating domestic hot water;(b) supplementary electric heaters; and(c) circulation pumps.

From the above it seems that so long as the heat generating part of the installation is new, then other parts of the heating system can be re-used.  This makes sense – it would be crazy to insist that a new biomass boiler installation also had to replace all of the connecting pipes, radiators and hot water cylinder in the home.

In relation to a solar thermal system, the parts of the plant that can generate heat are:

1. Solar Collector
2. Pump
3. Immersion heater in cylinder

Items 2 and 3 are specifically excluded in the regulations.  It seems to me that to modify an existing solar thermal installation so that it is eligible to join the domestic RHI scheme, it is necessary to change the solar panels, but that all other components could be re-used.

Have I missed something?