Bird Proofing for Solar Panels

Bird Mess

I was surprised when posts about ‘bird-proofing’ solar panels popped up in my Linked-in Feed the other day.  “Is this really a thing?” I wondered.  So I contacted the guy from the pest control company that was offering the service to find out more.

thesolarblogger:

“What damage do birds cause to above-roof solar systems like this? Why don't we see more of this kind of thing? Are birds a problem in only some circumstances or places?”

Kelly Farrant, pest control specialist:

“There are several reasons I get asked to carry out this type of work. Pigeons love solar panels as a place to build their nest as they protect them from the elements and is a safe environment for them from predators and humans. The two biggest complaints I get is first of all the noise, with the pigeons waking the home occupants around 3 or 4 in the morning every day with the bird noises echoing through the loft. The second is the mess they make. A heavy infestation can cause a blocked gutter in a week and over flow of bird mess down the side of the house, not nice if you have a white exterior. It also causes a lot of mess around the outside of the house which can also be very slippery when wet. Another concern is the constant collection of broken eggs and dead chick on the floor where they have fallen from the nest. The final reason although I have not heard it happening yet is a concern that the birds will cause damage to the cables. I have lost count of how many solar panel jobs I have completed this year but I would say it is over 40 with my best month being April when we completed 12 in one month. I hope this helps.”

Other LinkedIn-ers from the Pest Control Industry provided more background.

Mark Porter, Area Surveyor at Servest Pest Control:

“agree with the above. The guano deposited tends to build up & blocks up guttering. They also provide ample nesting sites to female birds looking to shelter the young from the cold & wet. with this comes biting insect activity that feed on the young while in the nest. Bird mite soon then become a problem for the resident when the chicks are strong enough to leave.… “

Barry D Phillips, a Pest Control Training Supplier:

"Everything Kelly just said plus the main issue with Gulls is they are attracted to solar panels as they see the reflection of the sky and mistake them for a pond , lake or other water source. They and Pigeons cause additional damage from via their fouling which is highly acidic and can cause erosion to certain materials and paint / or protective coatings. Gulls also like to drop items onto the ground from height so this explains a lot of the bones etc you may have found on some jobs."

So there you have it, yes bird-proofing solar panels really is a thing.

As if rack-mounted solar panels were not ugly enough already, you now need to cover the edges with a metal mesh to protect yourself from an infestation of pigeons or gulls that will keep you up all night with their noisy parties, fill up your gutters and damage your paintwork with all their poop, leave dangerous slip hazards on your garden path and infect you blood-sucking parasites....

Yet more reason to do the right thing and go for good looking roof integrated solar?

Nailed Down

Clearline Fusion integrated solar installed by Go Green Systems.  Image (C) Go Green Systems

Change to UK Roofing Standards with Consequences for Solar

The British Standard for slating and tiling (BS 5534:2014) was updated in August 2014, and after a period of overlap to allow industry to finish jobs already started the previous version was withdrawn in February 2015.

Although the building regulations do not specifically call it up, most manufacturers of tiles and slates make sure that their installation guidelines closely follow the standard.  In addition, architects and designers will use it in their specifications and providers of insurance warranties to housebuilders such as NHBC require that tiles and slates are installed in accordance with the standard (for example, see section 7 of the NHBC technical document). 

The bottom line is that most new roofs in the UK will now be installed to this standard and the changes have some impact on the installation of solar on these roofs.

Fixing of Underlay

The underlay resists a proportion of the pressure difference created across the roof by wind.  If it is insufficiently well secured, it can balloon up and press on the underside of the tiles or slates.  New guidance in the standard describes how the laps strips of underlay should be secured - either by covering the bottom edge of the lap with a batten or sealing between the laps with double sided adhesive tape.

Solar wiring is often passed through into the building by passing the cables up between the laps in the underlay.  However, the double sided tape used to  stick down the laps is so effective it can't be peeled without tearing the underlay.  Installers might be tempted to cut through the underlay to pass cables through instead of taking the more time-consuming option of running them up to the top of the roof and into the building through the ridge vent.

No Tile Without a Nail

BS5534:2014 has an updated wind speed map, in which the wind speeds have increased compared to the previous version. This apparently reflects the greater likelihood of extreme weather events in a warming planet, and aligns more closely with European standards. 

Whatever the reason for this change, the outcome is that where previously only single-lapped tile roofs in highly exposed locations would need to mechanically fix every tile, now pretty much every roof is going to have every single tile nailed, screwed or clipped down to the tile battens.

For a roof that has been laid in this way, the task of retro-fitting an above-roof solar system has just got much more difficult. 

With a loose-laid roof (perhaps with only every fourth course of tiles fixed) you could simply slide tiles up and under the row above to fix brackets to the roof structure below.  This trick is also often used to provide foot-holds on the roof and avoid the risk of cracking tiles by walking around on top of them. 

For a roof built to the new standard, this option isn't available.  Real care is going to have to be taken to avoid the risk of damaging the roof covering so access to the roof is likely to need to be on boards or roof ladders.  Removing and replacing tiles for fixing roof hooks is going to be significantly more time-consuming, perhaps involving ripping nails to remove  a patch of tiles for each roof hook and using adhesive to replace that final tile (since it's impossible to nail).  Installers  may find that removing a large area of tiles and replacing them with a roof integrated solar system is far less trouble.

As the years go by, to stock of homes in the UK that have been built or had their roofs re-laid since the standard was updated will slowly increase.  It will become less and less of a sure thing to assume that the roof of the building you are quoting to install on will have loose laid tiles.  Solar installers should be particularly wary when pricing jobs on homes that have clearly been built in the last couple of years.

Of course for those solar installers that operate in the new build market the impact of the change is immediate.  With a loose-laid roof it was previously possible to install an above-roof solar system on a new home just like a retrofit on an existing one.  Occasionally the roofing contractor would refuse to provide a warranty on a roof if a solar installer had been tramping round on top of it lifting and notching tiles to fix roof hooks behind them.  Then it might be necessary for the build programme to allow time for the solar installer to fix roof hooks after the roofer had battened the roof but before they had tiled it.  This now becomes the only way to work with a nailed roof and clearly requires an additional visit to site for the installer. 

Even then, when you come back to fit the rails and modules above the tiles you need to figure out a way to get the cables through  into the building.  The cheapest option is push the cable up through a notch cut in the back of the tile (hopefully with some protection against abrasion of the insulation such as a flexible plastic conduit).  Alternatives include a flashing with cable glands or a similar cable entry created with lead.  All these options are extremely awkward to install without being able to easily remove the tiles fixed down by the roofer.

Little wonder that with the advent of cost-effective roof integrated solar that has closed the gap in cost with above-roof kits, most solar installers working in the new build sector have decided that roof integration is the only way forward.  Not only are the aesthetics more acceptable to customers it's now just so much less hassle to install.  It needs only a single site visit to fit the system after which the roofer can fit the slates or tiles all around using as many nails as they like!


Acknowledgements:

Thanks to Etienne Hilaire  Avonside Renewables for their advice on the practical impact of the new standard.

Solar Attrition Rates

An Analysis of the MCS Installer List

I recently had the opportunity to have a look in more detail at the list of installers registered with MCS, and what I found came as quite a surprise to me.

The number of solar PV installers registered with the Microgeneration Certification Scheme (MCS) has been on a declining path since the boom of 2010-11.  This is not news to anyone in the industry.

Right now, the number of solar PV installers registered with MCS (removing duplicates) is around 2,640, a fall of 24% since 2013.  But when you look at the actual companies that make up this headline figure you find that less than 50% of the solar PV installation companies on the list in 2013 remain two years later. 1,822 companies have left the market, but 980 new companies have joined the list in the last two years.

Churn Rates in Solar Installation Businesses

Turning to the list of solar thermal companies, we see that the decline in numbers has not been as severe as for the PV installer companies, a 13% drop from 1,298 companies in 2013 to 1,130 now.  However, the churn rate is just as eye-watering.  Nearly half of the solar thermal installers registered with MCS in 2013 are no longer on the list, but the 635 that have left have been replaced by 467 new companies.

What's going on?  Are these attrition rates normal for similar industries (home improvements, heating, electrical works)?  Or is there something 'special' about our solar industry?

Is This As Good as it Gets?

The Case for Good Looking Solar

Is that really the best you've got?

Do you like your coffee regular, large, super size or in a 6-litre bucket?  Americano, double espresso, flat, cappuccino?  Perhaps chocca-mocha or the icy one (whatever that’s called).  With skim milk, full fat or a drizzle of lard?  Do you want them to sprinkle brown dust onto the foamy topping for you?

Henry Ford famously said that you could have his Model T car “in any colour so long as it’s black”.  From the vantage point of our highly developed consumer market how amusing it is to imagine giving customers such limited choice.

Well, dear solar industry reader, why not take a fresh look at what are we offering our customers.

“You can have any solar installation so long as the panels are 2m x 1m modules fixed onto a rack above the roof, the array size matches a standard kit from a merchant and the panels are arranged in a nice easy rectangular shape.”

Yes, we talk about black-on-black modules or silver frames, poly or mono, micro inverters, optimisers or string inverters and all the rest, but are these technical issues really of interest to any but the earliest of early adopters?

Your home is your single biggest purchase and the roof is a very visible part of its kerb appeal.  If, when you come to sell it, a proportion of your potential buyers are put off by an insensitive solar installation on the roof it could cost you a lot of money.

Image: Viridian Solar Clearline PV30 and PV15 roof integrated solar panels

Forward thinking solar installation companies are already positioning themselves for a ‘post Henry Ford’ solar market.  They realise that as we move past early adopters chasing lucrative Feed in Tariffs and on to convincing the early majority to go solar we need to listen to people’s needs and offer them more choice, for example

• Downsizing the installation to avoid over-crowding the roof
• Grouping panels to create a more balanced, symmetrical installation
• Roof integrated systems where panels look more intended and less like an afterthought
• Large format modules for less clutter on the roof
• Solar tiles and slates
• Complete solar roofs
• Offering solar thermal for roofs with limited space

As the costs of the equipment for solar installations have fallen, the extra cost of roof integration has fallen to the point where it can no longer be ignored as an option for customers.


But  the industry needs to overcome some prejudices.

First, on ease of installation.

Removing a patch of tiles adds very little extra work.  This is especially true for large format concrete interlocking tiles, which are quickly lifted.  Integrated solar panels are not just for new build.

Second, on maintenance.

A PV system should last more than 20 or 30 years so the chance is high that some maintenance of a roof covering will be necessary.  Even new homes may suffer a single cracked tile from a manufacturing defect or mishandling during roofing.

Replacing a broken tile is a simple and easy job for a roofing contractor working from a roof ladder.  If the cracked tile is behind a solar array, then it’s a very different situation.  Scaffolding is required, an electrician is needed to disconnect the solar and then remove panels to hunt for the source of the leak below.  A simple job costing £100 has become a costly exercise that could comfortably exceed £1000.  Looked at this way, roof integrated systems are preferable.

Third, on energy performance.

Everyone knows that integrated systems are going to run hotter than systems that have more open to ventilation, but how big is the actual effect on energy yield?  Viridian Solar recently published research on this subject in collaboration with the University of Cambridge Department of Engineering.  The answer turns out to be only 3%.

A new, sophisticated and more demanding breed of customers is emerging for the solar industry.  Less interested in details of the technology and less accepting of “one-size-fits-all” solutions.

More and more solar installation companies are seeking to escape the race to the bottom by differentiating their offer.  Building integrated solar panels are a way to broaden the appeal of solar to more customers and add value to your business.


This article first appeared in Solar Business Focus UK Magazine

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?

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.

 

 

Information is Beautiful

Why the solar thermal industry should embrace data logging

by guest blogger Ben Whittle

Who is this person that the Solarblogger has invited to wax lyrical on the rather un-sexy subject of data that you have never heard of before, I hear you ask?

Some might say my claim of authority to write on this subject is sketchy at best: I’ve only lived with and monitored a solar thermal system for less than 6 months, and I have only seen data from a few installations ever. But maybe that is exactly why it is a subject that needs discussing in the solar thermal industry… because I have been installing and designing solar thermal systems for around 10 years and I can count the number of installations I’ve seen that have monitoring on them on one hand, (and one of those installations is my own). And when I say we need more data-logging, I don’t mean turning on the heat quantity measurement function, I mean proper data-logging: measuring temperatures at the top, middle and bottom of the store, pump on and off times, boiler trigger times, heat measurement, the lot.

Over all the years I have worked in this industry I have seen a lot of mistakes made in designing and installing systems (and some of them were my own mistakes). How do I know they were bad designs and mistakes? Because I had to go and fix them. How can we possibly move on as an industry if we can’t try and make some sense of what mistakes were made in the past, and learn from them? Of course we have made leaps and bounds in some areas: the quality of the panels, plumbing, tools and fittings we are using (thank the lord for press fit pneumatic tools and filling pumps!), the MCS standards, the list goes on. OK, great, we can install stuff quickly and efficiently and it doesn’t leak… what’s the next step? Actually measuring how the systems are performing. Because I can tell you in the UK we have a long way to go in terms of getting our solar thermal systems to perform as well as can be achieved as seen across mainland Europe and America , and keeping track of performance is the only tool that can help us do it.

Now of course there are all sorts of reasons as to why we don’t normally achieve performance levels of a high quality Austrian installation… predominantly that is because the average UK house doesn’t have space for a 500-1000litre hot water store in the 700mm wide airing cupboard. But let’s put aside the things we can’t tackle and talk about the things we can.

To my knowledge there are only 2 or 3 solar thermal trials of any significance that have been published in the UK on solar thermal, and probably the best of these was conducted by the Energy Savings Trust three years ago. For those that are interested it’s called “Here Comes the Sun – A field trial of solar hot water systems”. It’s a great document, short (24 pages) and to the point. It tells you what you need to know – the biggest impact on solar thermal performance has nothing to do with evacuated tubes or concave reflector plates or low emissivity glass. But how did they reach those conclusions? By measuring things and writing it down – and, you know, analysing it and stuff.

And that is where we need to be going as an industry – looking at data, working out how to improve things, and changing our behaviour to suit. Not only will measuring performance allow us to understand the mistakes we make, it can inform our design decisions and help us to improve everything we do… and of course there are other benefits to consider as well.

1: Data logging is another chance to “add value” to your installation work. It’s a slightly more expensive controller, or an additional bit of kit to be sold, and a chance for your geekier clients to play with a spreadsheet or two. Now if you haven’t had a great experience installing solar thermal and the thought crossing your mind right now is “yeah right, and the customer is going to use this data to beat me with like a stick when it all goes wrong,” then I really am talking specifically to you. Because there are thousands of systems out there in the world that do perform absolutely perfectly, and as an installer you need to understand how they work.

2: It’s a chance to fault find, and take the correct action if things do go wrong, instead of guessing.

3: It will help you understand how people interact with their solar systems.

4: It can help get you out of trouble if the cause wasn’t your fault. One of the few logged systems I have seen was a school pool system that was constantly stagnating and losing pressure after being installed. When the data card was posted back to the company I worked for, it didn’t take long to diagnose the fault. The college maintenance man had been turning the system off at the main switch on a regular basis (even though it had a sign on it saying “Solar – do not switch off”). We were even able to re-program some of the settings using the data card and send it back to them in the post to plug back in. That’s quite an unusual feature specific only to the controllers made by Watts industries as far as I know, but a pretty handy one for commercial systems.

Just imagine what could be possible if we all took this a bit more seriously – imagine coming in to your office on a hot summer day in a few years from now after installing a 1000 systems across your local area, to find a couple of automatically generated emails where your data server had logged some de-pressurisation warnings at a couple of properties. You could then log on to watch some live system data to check them, and dispatch a maintenance team to fix them before your client was even fully aware there was a problem. All part of the regular maintenance contract you sold them at the time of installation…. There is no reason why this fantasy couldn’t come true, and it’s up to us to make it happen. It is already happening in the world of heat pumps.

As an aside, maintenance contracts are another area I think we need to explore further as an industry. I recently saw a report suggesting a very significant proportion of people who buy solar thermal systems would be happy to pay more than £100 for regular servicing, another possible revenue stream for any installation business.

Red=panel, Yellow = top tank, Blue = mid tank, Grey = low tank

R1 = solar pump on, Rs = boiler on

My own system does not have anywhere near enough data yet. I’m currently measuring temperature at 3 heights in the store, the solar controller also controls my boiler so I can also measure how frequently the boiler is getting activated, and I’m also getting estimated energy yield using the heat quantity function on the controller and estimated flow rates. In an ideal world I hope to add a water meter to measure my hot water usage, and a proper electronic flow meter for the solar controller to measure the glycol flow rates, and an electrical meter to measure electrical consumption. But I must be doing something right because I am currently hitting 2100kWHours of energy from my installation, after being installed for less than 6 months. And thanks to the EST solar study I know that the average UK installation is usually generating 1500kWH in a whole year… and I would never have found that out if I hadn’t bothered to log the data. Of course that generation figure could be inaccurate, and I mean to find out if that is the case by getting more and more accurate data over time.

I should probably qualify that performance figure by pointing out that I do not have an “average” UK system, so I’m comparing apples with pears… but I hope to explore that issue in a further blog post, looking into hot water storage, and how we might start improving solar thermal performance in the UK.

 

Let's Get Down to Brass Tacks

How to Sell Solar With the RHI

 

The shape of things to come?  Solar heating and solar PV in a combined installation.
Image courtesy : Viridian Solar

Perhaps inevitably, the first reaction of the solar industry to the new domestic Renewable Heat Incentive (RHI) has been to compare the financial returns for solar heating to the Feed in Tariff (FIT) available for solar photovoltaic panels.

A quick, back-of-envelope comparison is not normally favorable to the RHI, but a more considered evaluation raises some interesting points.

So, before you screw up your envelope and toss it in the bin, read on…

Wide Applicability

Solar water heating requires a much smaller area of roof than PV.  An area of 3 or 4 square metres (2-3 kWth) is ample for most households.  The average PV installation according to the Energy Saving Trust has reached 3.75 kWp or around 22 square metres.  Solar heating therefore is more useful for partially shaded roofs, where only a small part of the roof area can be used.

Because it takes only a small portion of the roof, it can also be more palatable for customers who are interested in the impact of the solar installation on the looks or re-sale value of the home.

The RHI will require only loft insulation and cavity walls to be filled, and only where it is practical to do so.  This means that any building can qualify at modest cost.  The FIT is limited to homes that can achieve EPC D, and many cannot except at exceptional cost. (I’m expecting the FIT to migrate towards similar qualification criteria to RHI – watch this space).

Solar heating is also less affected by orientation or the location of the installation, with a lower drop-off in energy yield for east or west facing roofs or installations in the north of the country.

These factors all contribute to a large potential customer base for solar heating.

Sweet Spots

As the Feed in Tariff (FIT) rates have fallen, energy savings start to feature more and more highly in the financial returns calculations.  Solar companies are starting to get used to the idea that the financial returns for PV now depend much more on the customer’s patterns of energy use and therefore the sizing of the system.  (See my blog on self-consumption of solar electricity here.)

The Renewable Heat Incentive for solar is set at a level where the return on investment also relies upon the amount of energy saving the customer achieves.  This creates “sweet-spots” with above average financial returns:

Larger families

On average, the more people in the house, the more hot water the household uses for showers and baths.  The same solar installation will produce a greater annual energy output when there’s more cold water to be heated up, and the MCS deeming method captures this.

Oil or electric heating

The more expensive the heating fuel being saved, the better the returns that are achieved.  Off gas grid installations will have a higher return on investment.

Cost Sharing

Installing solar heating at the same time as other necessary work can transform the return on investment.  The installation of a solar cylinder can be as much as one third of the cost of the installation.  If a customer was planning to replace an old hot water cylinder anyway, then going solar at the same time would make a great deal of sense.  The same argument goes for roofing repairs, where roof access costs can then be shared.

Rather than relying on chance to provide opportunities for cost sharing, the solar industry now has a gold-plated opportunity to create its own.

From “Either-or” to “Both-and”

A solar installer can create cost sharing to boost the return on investment for customers very simply.

Create your own sweet-spot by offering to install both solar PV and solar heating together. 

The shared costs of travel, roof access and roofing works provide obvious cost reductions, but it goes much further than that.  Because the average sales price per install is boosted the costs of customer acquisition (sales and marketing, survey) are also shared across more revenue.

Counting All the Pennies

When preparing a financial calculation for solar water heating there are a couple of important points that are easy to miss out.

First, the saving on the energy bill is not the same calculation as the solar energy added to the hot water cylinder.  The fuel burnt to create the same level of heat is higher because the back-up heater will operate with efficiency below 100%.  In fact, it gets better because the “summer efficiency” of boilers is lower than the “winter efficiency” because they have to heat up just to prepare the domestic hot water.

The new version of MIS 3001 proposes a range of “solar efficiencies” for different back up heaters, but a few of the more common ones are shown below:

The energy saving is the solar energy input to the hot water cylinder divided by the boiler efficiency.  Depending on the efficiency of the back-up heater in the home, the fuel saved can be as high as double the solar energy.

Second, the customer is getting a brand new hot water cylinder as part of their solar installation.  If it’s replacing an old cylinder with lower performing insulation and if it’s carefully installed with insulation on all the connecting pipes (not just the solar ones), then there is a significant energy saving for the customer.  When replacing an old cylinder with a properly installed new one, the energy saving averages 750kWh/year, adding around 50% to the energy saving.

These savings are real and they are significant, they should be taken into account in any presentation of the financial benefits of solar heating. 

Getting Emotional

The solar PV market has spent the last few years selling a financial product.  Cold, rational arguments about return on investment, fuel price inflation and comparative returns from ISAs have crowded out the emotional reasons people still have for buying into renewable energy: energy independence, climate protection, conveying their values to others.

Solar heating and solar PV top the charts as the renewable technologies most people know about and understand.  This is especially true for solar heating.

When you step under a hot shower provided by a solar heating system, you are provided with an intuitive, physical link to the energy you are producing.   A customers’ relationship with solar water heating is intimate and emotional.

After all, which other renewable energy technology do you get naked with?

People are not cold, profit-maximising robots - they are individuals with a wonderful capacity to  surprise. The solar industry needs to re-connect with all the emotional reasons for installing solar – oh, and by the way it makes great financial sense too.

Wrong on Many Levels

The solarblogger is Concerned For You

While out and about near Cambridge, I passed a building site and snapped this photo. 

 

Discretion is my middle name

I guess I was planning to rant on my blog about one or all of the following (take your pick):

• The box-ticking mentality that results in house builders giving their customers a 0.5kWp solar photovoltaic system – something that no one would ever buy for their own home (see my earlier blog Specifying Solar for New Build Houses)

• How there’s really no excuse for these solar panels to be installed like an ugly roof-rack (see one of my most popular blog articles – The Best Looking Solar Panels You’ve Never Seen)

• Why the designers didn’t choose one of the many low-profile roof integrated solar options that would have been so very easy to do as a new roof was going on anyway.

It was only when I downloaded the photo and reviewed it on a larger screen, that I realised what I’d inadvertently caught.

Did you see that in the background?  If the guy working on the roof between the solar panels slips, they’re both coming down.

Can you see what it is yet?

I’m guessing what we’re looking at here is the result of having to install to a price. In new build, the panels are often fixed in place by the roofing contractor and you can’t complete the electrical installation until there’s mains power in the house (which normally means long after the scaffolding has gone). Repeat visits to site are costly, better to do it all in one trip than to make the electrical connections to the panels when the scaffold is up.  Must be really tempting to just nip up there on a ladder and get it done.

Is there a better way?  Well, one option is to roof-integrate the solar panels at the same time the roof covering is going on, pass the electrical connections from each panel through into the roof space and the whole system can be connected up from inside the building.

Perhaps you think I'm worrying unnecessarily for the welfare of my solar colleagues?  Is this 'elf and safety gone mad?  If the ladder was tied on, would that make it OK? Please post your thoughts in the comments box below...

Note Added: 22/07/2013

People have started to send me photos of their own - I have started an image set on Flickr here.  Please keep 'em coming!