/ Home & Energy

No wonder we’re confused about renewable energy

Man installing solar panels

Q: How do you know if getting a solar panel, heat pump or wind turbine installed in your home is the right option for you? A: With great difficulty, and lots of confusion, so it seems.

I wasn’t surprised by the results of a recent survey asking 200 homeowners how they felt about small-scale home energy technologies.

Two-thirds told ReEnergise Renewables that they didn’t know enough about the various options available to make an informed decision on whether any were worth the investment, despite 80% supporting the idea of renewable energy in general.

The idea of a shiny solar panel on your roof certainly sounds eco-friendly – and lucrative too, in light of the Government’s feed-in tariff scheme which offers payments in exchange for generating renewable electricity.

But in reality, useful, tailored advice on viable options for your home is hard to come by – and practical trials of some microgeneration technologies have yielded disappointing results so far.

How renewable installations stack up

The UK’s largest trial of wind turbines conducted by the Energy Saving Trust in 2009 highlighted the poor performance of urban or surburban-sited installations. Only freestanding wind turbines in remote rural surroundings exceeded performance expectations.

Ground source heat pumps may be one of the technologies included in government plans for a Renewable Heat Incentive. This scheme is akin to feed-in tariffs, guaranteeing payments in return for installing low carbon heating tariffs. But only a staggering 13% of the 83 heat pumps monitored (again by the EST in 2010) achieved an efficiency level deemed ‘well performing’ – with poor quality installation a key factor.

Our investigation last year into solar water heating installation companies, meanwhile, uncovered dodgy sales tactics and misleading claims from installers – the very professionals homeowners are relying on for practical advice.

Is generating your own energy right for you?

Microgen technologies are not ‘off the shelf’ products. The suitability and size of a system for your home will depend on the type, age and location of your property, the fuel you currently use and your average energy consumption – amongst many other variables.

Given the complexities involved, not to mention the steep upfront costs, you should think long and hard before deciding which – if any – is suitable for you.

Seeking professional advice from an impartial body such as the Energy Saving Trust is also wise, with its home energy generation selector tool being a good first port of call. And before you do anything else, make sure you’ve explored lower cost energy efficiency options like insulation.

Don’t get me wrong: the right technology, properly installed in the right location can provide a low-carbon, low-cost means of powering your home that pays for itself (and more besides).

But at the moment, it feels like a reliable source of information to help understand what these ‘right’ conditions look like – applied on a home-by-home basis – isn’t easy to come by. Who would you trust to fill the information gap before investing your thousands?


I agree that this is a veritable minefield.

I’d make two points really:

1) in my experience solar water heating (which I have) costs only about 35% of the average figure quoted by the “big names” if you get it via a reputable plumber or small solar company. I used Aztec (I have recommended them on Which? local) and paid well under £3k for the whole lot including a huge new twin-coil cylinder and longer than average pipe runs. The quotes I had from a well known double glazing company (think feathers and helicopters) and a solar company who were touting for business in the area were both for well over £8k and neither of them included a new cylinder, only modifications to the existing one. I get 100% of my hot water from solar between about Easter (or sooner if Easter falls late) and late September. The water is often too hot for safety really, so there is no question of this being a bad buy, although it will still take me about 9 years at today’s gas prices to break even.

2) I hate to say this but I will never trust the EST ever again after they recommended a washing machine which I eventually proved was anything but energy saving (I’ve posted in detail on other boards, I’m not going to waste space and bore readers here with the details again). The fact that the EST’s Home Energy Selector Tool tells me that my directly south facing, fully exposed, roof (on which I have already got my solar panels) is unsuitable for solar panels as it is in shadow (eh?????) doesn’t greatly inspire confidence in that either I’m afraid.

My recommendation: speak to people who have a successful installation of whatever technology you are interested in, get the details of their suppliers / installers and start from there.

I have installed Solar Thermal (hot water) and Solar PV on my house. The Solar Thermal was installed five years ago and the Solar PV two and a half years ago. Fortunately I have a south facing roof of modest proportions, located in the south of England. I am also expecting to expand my Solar PV array and migrate to an air sourced heat pump in the forseeable future.

The drivers for this are as follows:

Solar PV. To exceed my current demand to provide spare generating capacity to charge electric cars in the future. A solution to the potential fire hazard with Lithium Ion batteries in a crash scenario is being researched at a variety of locations around the world.

Heat Pump. To replace or reduce the consumption of gas for space heating. It is a fossil fuel, which is likely to rise in cost substantially, alongside oil, as demand exceeds supply in the post peak oil era .

At the heart of any decision to invest in sustainable energy are two factors: economics (expressed in two “languages”) and a will to be more sustainable.

Firstly, in the context of Solar PV, economics needs to be based on kWh for energy generated (and used) and also in financial terms. For example, I am currently generating about three quarters of my energy needs (kWh) and the value of the energy I generate exceeds the market value of my energy consumption (£). In other words I make a financial surplus that is used to pay back the investment in the technology.

I would recommend installing the largest capacity array of Solar PV panels that can be afforded or appropriately mount on your roof. The larger the generating capacity of the array (measured in kWp – kilowatt peak) the more likely you are to get close to, meet or exceed your electrical energy needs. Don’t forget that panels mounted at any angle other than due south will not generate so much electricity and shading is an issue that needs addressing.

My Solar Thermal fit generates approximately 70% of my hot water needs across the year. It heats water on sunny winter days and heats all the hot water for most of the three other seasons. Remember that for every degree that the sun heats your water, you do not need to heat it using fossil fuels at increasing expense.

How might you go about installing a sustainable energy solution? Firstly it might help to read Professor David MacKay’s book “Sustainable energy – without the hot air”. This is available in print (ISBN 978-0-9544529-3-3) and free on the Web (www.withouthotair.com). This is a much praised authoritative work that will help you understand what the motivations are for using sustainable energy and even more helpful, the various technologies are explored with figures included.

When you have decided what solution you wish to persue, compete accredited installers by inviting them to quote for an installation defined in CAPABILITY terms, leaving the technical and design risks in the hands of the installer. Any good installer will engage with you at an early stage, even before defining what you want.

The criteria that I used to choose an installer were:

Company integrity.
Energy Saving Trust accredited installer – tecnical competence.
Customer focus. Happy to meet my needs rather than flog me something that I did not want.
Happy to provide other customers details for quality verification.
Minimum disturbance from installation.
Leave the site clean and tidy during and after installation.
Good value for money – considered only after addressing previous criteria.

For Solar PV, use the most efficient panels on the market, usually monocrystalline.

My fit is a 3.075 kWp array of 15 SunPower Inc (USA) “205” monocrystalline PV panels arranged in three strings facing 185 degrees. This array is fixed to the roof; however, were it to be fixed to a device that tracks the sun is it moves across the sky, it would be even more efficient.

For those contemplating windpower, an interesting site to explore is http://www.segen.co.uk.

Finally, The Government has announced that the total funding available for feed-in tariff payments for all technologies, including solar PV, will be capped at £360m by 2014. This is a reduction of 10% due to the Comprehensive Spending Review. This may seem a long way off and £360m a lot of money, there is a strong possibility that the feed-in tariff rates will need to be reduced before then to prevent the budget from being over spent. The Government has reiterated that should that happen no existing installations will be impacted as no change will be retrospective, so once a system is installed it will continue to attract the initial feed-in tariff rate for its full term. So, be reminded that delaying a decision could cost you money.

The uncertainty surrounding the Feed-In Tariff, the Renewable Heat Incentive and other grants really puts me off. There appear to be no concrete guarantees of which technologies will be covered under some of these schemes, how payments will change over time and whether they will continue to run for the periods promised. There are also too many inconsistencies regarding performance and longevity of some technologies – I must have seen eight different lifespans for solar PV panels while shopping around online.

I presume the feed-in tariff was designed to stimulate take-up of microgeneration to achieve government targets. If this is so, it is not unreasonable to expect the scheme to be finite, even if frustrating. But who would trust a government? It has wiped billions off people’s pensions by the switch from RPI to CPI in a stroke!

What is clear is that FiTs is approved BEFORE installation takes place and therefore the risk is lowered in this respect.

With regard to lifespans of technologies some guidance can be had from the period manufacturers are prepared to guarantee their products. In the context of Solar PV panels, this seems to be for about two thirds of their expected life. But what can go wrong? There are no moving parts, simply a very thin silicon laminate under tougened glass fixed to a frame to aid securing it on a roof. My Solar PV panels are guaranteed for 20 years and the electronic inverter for 10 years. By then, research will have developed even more efficient ones.

With regard to other technologies, particularly emerging technologies and those with many mechanical parts (wind turbines, Arhimedes screw and water turbines) it is less clear. However, a friend of mine in Germany has converted his grain mill into a power station by replacing the mill wheel with two submerged water turbines driving generators through gearboxes and a belt drive. His only expense is special bearing grease which is pressure fed to the turbine bearings and, having returned to the mill house, is sent for recycling. For clarity, grease is pumped from one tub to the bearing through a narrow pipe and returns through a separate pipe to another tub to be sent for recycling..

My advice is to read the product manufacturers literature and call them with your questions.

I’ve developed a bit of an interest in this field over the last couple of years. I’ve read lots of articles, read the claims from those selling the equipment and done my own research.
I’m no eco evangelist, the need to reduce carbon emmissions might well be true but the chances of getting global concensus is I believe very slim, so eventually we (humanity) are stuffed, but not for a while yet.
The immediate issue for me is the economics and the source of the energy I need to live a reasonably comfortable life. I’m all for renewables but perhaps for different reasons. Things like energy security and cost are the major factors in my agenda.

I’ve reached my own conclusion on three renewables currently being pushed on the public.

Solar water heating:
Most adds suggest you’ll get 50% of your hot water from perhaps May to September.
I use a gas combination boiler for heating and hot water. May to September the heating is usually off so its just hot water. This costs close to £8 per month.
A solar hot water system would cost approximately £3500 to £4000 and save me £4 per month six months of the year.
You don’t need a degree in maths to work that one out do you?

Solar PV:
To make it worthwhile you’ll need an array rated at at least 2.5Kw to save about 35% of your electricity bill.
Ha but what about the feed in tariff, 43p or so per unit?
Well you might make as much as £800 per year tax free from the FIT, but for that you’ll need probably more than 2.5Kw and might be shelling out as much as £15,000 or even £20,000 for the installation.
The PV array might have a working life of 20 years, 25 maximum but from about year 10 will gradually lose efficiency. I wouldn’t expect the FIT to increase above 43p so the best payback would be about 18 years depending on the hours of sunshine. If the installation lasts 25 years you might make about £5000.
I make that about 1% per year on your investment, and not exactly instant access.
Nice peice of “eco bling” but I’d wait a few years. The cost of PV will reduce over time as economies of scale and technological advancements are made.
Borrow to fit PV and you’re on a definate loser.

I’m a mechanical engineer and I’ve built a few of these, improving the design each time. For about £100 you can build a small (1.5 to 2m) which will produce a couple of hundred watts in a stiff breeze. Mine keeps a bank of 12v batteries charged. This when fed through an inverter to produce 240v AC will give me light and say TV for perhaps 12 hours.
It’s a useful “power cut kit” nothing more. I got a kick out of building something that worked but you could do the same by just keeping the batteries charged via the mains at very little cost.
Small wind turbines are next to useless in urban areas, too much turbulance, they need a steady wind flow. I live next to farmland so mine works reasonably well.
Shell out £1500 to £2000 for a small 500 watt rated installation which in practice will deliver maybe 200 watts (sometimes) and your payback calculation will give the answer, “never”.
Get a big one rated at several Kw and install it on the top of a hill and you will get some real power out of it but you’ll pay out many tens of thousands and you need the site, and planning permission.

So how can we achieve some cost benefit from renewables?
Or how can we reduce our energy costs? (and our carbon footprint if you’re an eco warrior)

Well most of our energy cost is in space heating so thats where to start looking. As you need to replace your heating system check out the most efficient at the best price, and insulate, insulate and insulate some more.

I’ve installed a log burning stove, I have a chainsaw, and I’ve got more insulation than B&Q, both in the loft and under the suspended floor downstairs, the wall cavity is filled, we’re double glazed and draft excluded everywhere.

My next little experiment will be in low cost solar space heating. I plan to build a collector box, plywood, aluminium cans and glass. Air will be circulated from the house through and back using little 12v computer cooling fans. I got the idea from the web, these are used it seems to good effect in Canada.
If it turns out not to work too well then at least I won’t have spent much finding out, unlike those going for some of the other “professional offerings”.

I hope what I think is a practical approach to the subject is helpful, and I’d wecome any comments.

John says:
10 June 2011

A point to consider in assessing if micro- renewables are right for you, is the need for planning permission. The Uk Government has removed the need for planning permission for micro-renewables, installed within the garden (curtilidge) or on a residential house, with a number of exceptions. Air Source Heat Pumps ,are excluded from the permitted development order.

It is always best to check with youre Local Planning Authority, normally youre local council, before installation. Planning permission typically costs, £150(excluding the cost of any plans or supporting information required) and takes 8 weeks to decide, once all the required information has been received.

Alan says:
11 October 2011

A couple of points in favour of solar.

1) Solar water, I heat my water with electricity which is more expensive than gas so the payback is quicker than suggested above. Also it works all year round, in winter it doesn’t heat the water to 90 degrees (there’s a regulator that mixes water to 55 when it leaves the tank) it heats it to between 30 and 40 degrees. Then I top up with electric. You are saving money all year round. It works when it’s cloudy, but obviously not as well. I think the calcs in the prvious post are very pessimistic.

And there’s nothing as satisfying as a free hot shower :o)

2) Solar electricity. My system cost £12k (3kWp and on current numbers will pay back in about 9 years. I base that on, 43p per unit generated (FIT), 3p per unit for 50% of generated (sell back to grid) and 10p per unit for 50% generated (electricity I don’t have to buy assumed usage).

The panels are guaranteed to be 90% effective after 25 years. The FIT is guaranteed (OK, UK govt guarantee so not cast iron) and index linked.

Current numbers indicate I will earn over £25 on a system that cost me £12K. All sensible estimates.