Domestic RHI - When can I join?

More clarity on legacy applications

simple!

If you have installed a qualifying renewable heat installation since 15th July 2009, you can join the domestic Renewable Heat Incentive (RHI) when it starts next spring and collect seven years' worth of payments.

The Department of Energy and Climate Change (DECC) published further details this week on the RHI that among other things outlines how applications from so-called 'legacy' applicants will be managed.  Application dates will be staggered as shown in the diagram above in an effort to prevent the administration of the scheme being overloaded.

Installations that did not receive a Renewable Heat Premium Payment (RHPP) voucher can apply from the day the scheme launches until the end of 12 months from launch.

Installations that received an RHPP voucher with an application date before May 2013 can apply from 3 months after the scheme opens for a period of 9 months.

All other installations (those that received an RHPP voucher with application date after May 2013) can apply from 6 months after the scheme opens for a period of 6 months.

How to Lower Energy Bills

The way the energy companies structure their tariffs encourages high consumption. 

Try to imagine a fee structure for gas and electricity that would encourage people to conserve energy. Forget for a moment how energy is delivered and what the costs look like for energy companies. We're not designing it to suit them. 

I suspect that you've come up with a scheme where the price of the energy you buy rises for each extra unit you consume, perhaps something like this.

A rising 'marginal cost' of energy would encourage investment in energy saving technologies

Energy companies have the technology to include information on your bills about how your consumption compares to similar properties around you, perhaps the price per unit could stay low until you exceed the average consumption in a comparison group. 

In this utopian vision, pricing signals would be incentivising people to invest in energy saving measures for their properties to reduce their energy use.  This would then lower the average energy use.  The level at which prices jump would fall over time, driving people to further reduce energy use. 

Burn baby, burn

Instead energy companies have structured prices to suit themselves. There's often a fixed "standing charge" which you pay even if you use no energy, helping ensure they recoup their fixed costs. Then there's a band at a higher price per unit for the first so many units, falling to a lower price per unit for all energy used above this level. 

If I had asked you to design a fee structure that encouraged high levels of energy consumption, you'd probably have come up with something like this. 

Which shouldn't be a surprise, really. 

We've left the fox in charge of the hen house.

The more you use, the lower is your average price per unit. The less well off, struggling to afford their bills and conserving the amount they use are paying the highest price per unit of any of us. 

Unsurprisingly perhaps,  energy companies structure our bills to reward higher consumption

Energy companies are being allowed to structure our energy bills to encourage us all to burn the planet and to discourage investment in energy efficiency.  

The current bluster about freezing prices temporarily or rolling back the 'green crap' is tinkering at the margins. (See my earlier blog - The State of the Debate).  A bold reformer would mandate an inversion of pricing structures to lower costs for the less well off and encourage us all to invest to use less energy. 

This would be market economics red in tooth and claw. Forget the Green Deal, forget Feed in Tariffs and Renewable Heat Incentives.  Forget all of the bewildering array of centrally planned, market distorting energy efficiency schemes.  Price energy use accordingly and watch it all happen based on millions of people doing what's right for them and their home. 

Optical Properties of Solar Panels

 

All you ever wanted to know about Incidence Angle Modifiers…

When light strikes a transparent material, some of the light is reflected, some is absorbed on the way through and the rest is transmitted.  For low iron glass of the type used in solar panels with the light arriving ‘straight on’ (perpendicular to the surface) the figures are typically 8% reflected, 1.5% absorbed and 90.5% transmitted.
 





Light incident on a the clear cover for a solar panel is mostly transmitted, but some is absorbed or reflected

 

 Most of the light incident on a solar panel does not arrive perpendicular to the surface, but at some other angle as the sun moves across the sky over the course of the day and year.  The incidence angle is defined as the number of degrees between a ray of light and the line perpendicular to the surface.  As the angle of incidence increases so does the proportion of light reflected at a glass surface.  Since the light is not travelling straight through but at an angle with a longer path through the glass the proportion of light absorbed by the glass also increases.




As the light arrives at shallower angles, the proportion reflected increases

 The effect  light angle has on solar panel performance is quantified by a property called the Incidence Angle Modifier (IAM).  The IAM is measured and reported as part of the standard test procedure for solar panels and is defined as the efficiency of the solar panel at a given incidence angle divided by the efficiency when the light arrives perpendicular.  It takes into account not only the changes in transmission at the glass, but also any changes in reflection at the absorber.

For a flat plate solar collector, the IAM starts at a value of 1.0 when incidence angle is 0 and decreases as shown in the diagram as the incidence angle increases.

 

The incidence angle modifier captures the loss of efficiency as the angle of light changes from straight on



Evacuated tube type solar collectors have a different geometrical relationship with the light from the sun.  Only the light arriving on the centreline of the tube will arrive at the glass with an incidence angle of zero, as you move away from the centreline, the incidence angle increases and the so the proportion of light reflected and absorbed also increases.  This is partly explains why evacuated tube collectors often have a ‘zero loss efficiency’ (or optical efficiency) lower than that for flat plate solar collectors (the other factor being the gaps between the glass outer and the light absorbing surface inside).

Since a tube has circular symmetry, the proportion of light transmitted is unaffected by the direction the light is coming from.  The light passing through the outer glass wall for a single tube would be unaffected by the angle the light arrives from in the transverse direction (around the tube).

 

The geometry of a tubular solar collector gives higher reflection losses for light arriving straight on
but has circular symmetry, so the reflection doesn't change as the light angle changes

 

An evacuated tube solar collector is made up from a number of tubes installed side by side.  A gap is left between the tubes so they don’t touch one another and there is a gap between the outer glass and the inner light absorbing surface.  Consequently, a proportion of the light is not collected and passes between the tubes.



Tube collectors have gaps between each tube which cannot collect light

 

Some evacuated tube collectors have a tubular shaped absorber (so called Sydney Tubes or tube-in-tube collectors).  A feature of the geometry of these is that as the angle of incidence increases in the transverse direction (around the tubes), the absorber area increases compared to the effective area of a planar absorber – less light passes through the gaps. 



Tube collectors with tubular shaped light absorbing surfaces 'close the gap' as the light arrives at shallower angle

 

The transverse IAM for these products rises higher than 1.0 before falling to zero as the angle approaches 90 degrees. 




The IAM for a Sydney tube collector rises above 1.0 as the light arrives at shallower angles

All this is just another reason why you can't compare solar thermal panels by their simple gross efficiency.

 

 

The State of the Debate

On the subject of energy bills our political masters prefer to treat us like children 

1. What a Grown Up Conversation about Energy Bills Looks Like

 

Electorate: "blimey, these energy bills smart a bit. I'm not very happy about that."
 

Government: "Yes, we can see why, prices for gas have doubled since 2005. There's a growing middle class in the developing world who want the same standard of living as us and fossil fuels are getting more expensive to extract.  I'm very sorry but we can't control the global price of energy."

Electorate: "are you saying that it's just going to keep on getting worse?"

Government: "no, we're saying that energy is going to get more and more expensive, but your bills are calculated by multiplying the cost of energy by the amount you use."

Electorate: "so you're telling us to share our bath water and wear two jumpers in winter?"

Government: "the UK has among the least energy efficient housing in Europe! perhaps it's time to start thinking about investing in your home. Why not install insulation or solar water heating to reduce your heating bills or make your own electricity with solar PV panels?  We have support schemes to help with the costs of these measures."

 

2.  What we get Instead

Electorate: "blimey, these energy bills smart a bit. I'm not very happy about that."

This Lot: " the energy companies tell me that it's all down to the green tariffs (which, by the way, the other lot brought in). We'll make the horrible bills go away for you, leave it to us."

The Other Lot: "No, no, no!  It's all down to those nasty profiteering energy companies.  Leave it to us, we'll make a law to stop price increases so those fat cats can't charge you so much money.”

 

 

It's time our politicians squared with us.  Go on, tell it how it is, we're all grown ups here, aren't we?

 

 

 

Heat and Power

Early signs of a rebalancing of the renewables market

The Microgeneration Certification Scheme (MCS) November newsletter was recently released, and a graph caught the eye of the solarblogger.  It is reproduced below.

The total number of MCS registered installers has been falling for some time.  Companies registered to install photovoltaic (PV) solar technologies dominate the numbers, and since the painful tariff adjustments of 2011, the number of registered companies has been steadily falling.  In the last 12 months the number of solar PV installers has fallen from around 4,300 to around 3,000.

Two features of the scheme may mean that even these figures are an over-statement of the number of active PV installation businesses.

First, since businesses renew annually with the scheme, a company decision to exit a market can take some time to feed through into the figures.  Falling registration figures will trail by an average of six months.

Second, renewal is significantly less expensive than a new registration with the scheme.  This asymmetry causes business to retain their MCS registration even when they are not actively working in the market “just in case things pick up.” 

Industry colleagues estimate that around 10-25% of MCS registered PV installers are not actively selling solar PV.

But none of this is news.

The thing that really jumped off the page for the solarblogger was that while the registered PV installer numbers have continued to fall, the total has actually risen since August 2013. 

There has been an increase in the number of businesses registering to install heating technologies such as biomass, heat pumps and solar thermal. 

Details of the domestic Renewable Heat Incentive (RHI) were announced in July 2013.  This scheme pays households that install heat-generating renewable technology and will go some way towards rebalancing the UK government’s lopsided support for renewables.  A successful domestic RHI alongside a stable Feed in Tariff could deliver long term growth for both renewable heat and electricity.

It seems like industry might just be starting to believe in the RHI.

Save the Merton Rule - Have Your Say

The Housing Standards Review Consultation closes in a week.  DCLG’s proposals will remove the Merton Rule, whereby Local Authorities can require developers to go beyond the Building Regulations on energy efficiency.  The Building Regulations themselves are not providing a pace of improvement to support renewable energy in new buildings and seem unlikely to do so for years to come.  We need to make our voices heard on this issue at DCLG.

Want to make a difference, but a bit short on time?  The solarblogger has helpfully done the hard work for you.

 Simply cut and paste the text below into an email and send it to:

HousingStandardsReview@communities.gsi.gov.uk

---------

Subject: Housing Standards Review Consultation

Dear Sirs

I wish to register my opposition to your plans to repeal the Planning and Energy Act 2008 before you have implemented Zero Carbon Homes.

Please carefully read the following three articles:

A Million Missing Low Energy Homes

Zero Carbon Homes, Carefully Check the Small Print

Lessons from the Sustainable Building Regulations in Scotland

With kind regards,

Solar Energy Redeemed

The Last Piece Falls into Place for the Domestic RHI

A hot prospect? 
Image courtesy Viridian Solar

 

 

MCS recently unveiled its new calculation methodology for predicting the energy benefits of solar heating, and its great news for the industry. The announcement was eagerly awaited not least because it will be the way payments are calculated under the domestic Renewable Heat Incentive.

What's Changed?

The previous version was based upon the government's Standard Assessment Procedure (SAP), and so is the new version, but with some rather important changes:

1.  The Number of Occupants

Arguably the single biggest factor impacting the solar heating energy yield is the amount of hot water used, and in domestic properties this is almost entirely down to how many people live in the house.

The previous version of the calculation followed SAP, which was originally developed for new build where the number of people using hot water in the building is not normally known.  The SAP calculation predicts the occupancy from the floor area of the property, with an increasing number of occupants as the property size increases.

Because this SAP calculated occupancy peaks at around three people for homes that are not abnormally high, it is underscoring the potential for solar energy greatly for the many households with more people than this. If this were to have been used for the RHI payments it would incentivise a solar installation in a mansion with a retired couple living in it over a smaller house with a family of five living there.  

The new calculation requires the solar installer to enter the actual occupancy of the property at the time of the installation, taking into account any part time residents (for example children that visit regularly but who don't count the house as their primary residence).  Installations will be subject to random audit by OFGEM, discouraging potential cheating, but for RHI deeming purposes, it was also decided to limit the occupancy to six full time equivalent.

This change is broadly neutral for smaller households of one or two people, and increasingly positive as the number of occupants increases. The new calculation will significantly boost the energy yield for larger households, rewarding those solar installations that deliver the highest energy savings. 

2.  Electric Showers

The SAP calculation assumes a certain hot water use per person. In the previous (2009) version, the hot water use was based on an average for all homes in the UK including those with an electric shower.  Electric showers are fed with cold water so don't use water from the hot water cylinder and this has the effect of lowering the hot water use in the UK average.

By separating out homes without electric showers, in the 2012 version, hot water use is boosted by around 30 per cent and the benefits from solar heating further increased.

Incidentally, this welcome change should see some of the daft (predominantly new build) installations disappear where solar water heating has been installed alongside electric showers.

3.  Backup Heater Efficiency

The previous calculation worked out the solar heat input to the hot water cylinder and this was the figure presented to the customer.  The new calculation recognises that the customer is more interested in their saving on energy bills, and this is not the same thing.  Why?  Because the boiler that would have heated the water if the solar system wasn't there works with an efficiency, so in most cases the fuel energy bought  is higher than the energy input to the cylinder.

For example, a boiler operating with 80% efficiency would need to burn 1,250 kWh of gas to produce 1,000 kWh of heat. (1,000/0.8 =1,250)

It turns out that backup heaters have a summer and winter efficiency. Most are less efficient in summer than in winter - energy overheads from starting up are a larger proportion of energy delivered when you're only heating water and not heating the whole house too. Of course, most solar energy is delivered in summer when the back-up heater is least efficient.

The calculation takes this into account and a "solar efficiency" figure is used to calculate the energy saving as well as the renewable energy. The figure is expressed as an "additional fuel saving" so should be added to the deemed renewable heat to arrive at the total energy saving.

4.  Irradiation

Where the previous version used a single irradiation for the whole of the UK, the new version divides the country into 21 regions (see my earlier article on SAP 2012). The UK average remains the same, but some regions are lower than the average and some higher.

In addition, the irradiation is calculated for the absolute angle and orientation of the panel instead of using a look up table. 

5. Cylinder standing losses

A standing loss for the cylinder is added to the hot water demand increasing the total heat load that the solar system can contribute towards.

6. Other Minor Changes

The second order heat loss coefficient for the solar panel performance is taken into account.

Homes designated water efficient under Approved document G have their hot water demand reduced by 5%

Believe it or not, there are solar thermal panels out there with efficiency lower than the SAP default. A loophole where these could use the SAP default values has been closed.

 

The Effect of the Changes

 

Let's run a few examples through the previous and new calculations. To keep things simple, we'll use the same high quality solar thermal panel for each situation, as well as keeping the shading (none or very little) orientation (south) and pitch (30 degrees) the same for all options.  We’ll also locate the panels in Sheffield (which receives the UK average irradiation) and remove electric showers from the house.  We'll assume the house has a modern condensing gas boiler.

For the previous calculation, I have used a house size of 85 m², an average sized town house with three bedrooms.  For the new calculation, a range of occupants between two and six is considered, with a panel area and cylinder size chosen appropriately.

The previous calculation ignores the actual number of people who live in the house and uses 2.7 residents in all cases, a figure derived from this floor area.  The results highlight the way that the previous calculation under-sold the benefits of solar in situations where more people live in the property.

In addition, the energy saving presented to the customer was the solar heat added to the cylinder, ignoring the efficiency of the boiler.  The new calculation takes the boiler efficiency into account. 

The new calculation gives energy savings between 50% higher and 142% higher than the old calculation.  The deemed renewable heat is calculated to be between 14% and 85% higher.

Many solar installers would have been disappointed by the tariff level of 19.2p set for solar heating under the forthcoming domestic Renewable Heat Incentive.  This improved calculation method provides just the boost that solar heating needs, and radically changes the economic attractiveness of solar heating within the domestic RHI.

 

The announcement of the RHI deeming calculation for solar heating is the final piece in the jigsaw.  Finally, solar installers can get out there and start presenting the financial benefits of the domestic RHI to potential customers.  In fact with a £600 upfront grant available for installations before the start of the scheme, there's every reason to install solar now.