Wednesday, 2 December 2009

Solar hot water panels - one person's experience

A more personal topic this week – I’m going to tell you about having my solar hot water system installed (it all happened in the 2nd week of November). And there’s a reason for telling you about it: there’s lots of good research showing that we are far more likely to do something that seems challenging if someone we know (or know about via a trusted route) has done that same thing. Personal contact has more influence than impersonal information in printed form (for more on this, see below).

This is really good news, of course – it means that the ‘green’ things we do, and are seen to do, have influence on others because it makes something unfamiliar or daunting seem possible and accessible. In fact, the firm I employed to do the work came by just such a route: recommended to me by a F/friend who is a few months ahead of me with all this; and as soon as this work is finished, I’m going round to see her next project – solar electricity (also my next project) – and talk to her about the firm she used for that.

For some readers, all this will be nothing new – but I hope it’s encouraging for others who haven’t ventured this far yet. And just to be topical – on November 11th (the 3rd day of the work being done) The Guardian had a front-page story headed, ‘Green home makeover will cost up to £15,000, says climate watchdog chief’!

It’s important to say that the venture into solar panels comes after having done all the cheaper and easier things: double glazing, cavity-wall and loft insulation, changing all the light bulbs; and replacing my end-of-its-useful-life central heating unit with a more modern and efficient one.

My house is a central terrace house facing almost exactly east-west (the back of the house actually faces west-to-west-south-west), so I don’t have a south facing roof. So I have a ‘split’ system, with two panels facing west and one panel on the front eastwards facing roof. If a house like mine had a south facing roof, I would only have two panels, so the third panel compensates for the less-than-perfect orientation.

The heating in my house is gas-fired ducted warm air, so there’s no gas input to any hot water – up until now my hot water has come entirely from an electric immersion heater. This has been my single biggest use of electricity, and makes the financial return from solar hot water panels quite significant, in addition to their ‘green’ credentials. This also means that my installation was slightly simpler than one which would have to be plumbed into a boiler that heated both the house and the hot water.

The new system still has an immersion heater, which I can use for ‘top up’ if and when necessary – but even then it will be heating water that is already warmed to some degree, so will be much more energy efficient. My old copper tank has been replaced by a stainless steel pressurised tank that comes with much more efficient insulation than before; and because it’s pressurised, I’ll be able to run a shower directly off the solar-heated water in the tank, instead of needing either a pump or an electrically heated shower.

The whole process took 5 days, Monday to Friday.
Monday: scaffolding erected, preparatory electrical work done, and new tank in place, though not plumbed in – so I was one night without hot water. The only reason for this was that the equipment suppliers were very late with their delivery (mid-afternoon instead of early morning). The plumbers were frustrated at not being able to get on. If the delivery had come in time, I would have been without hot water for only a few hours during the first day of the work – so the whole process isn’t hugely disruptive. When the guys went home at the end of the first day, the panels were left propped against the wall in my front hall and my cats were deeply curious!
Tuesday: new tank now plumbed and wired in and checked over; expansion tank installed in the loft out of the way (this is a safety feature because the hot water is now in a pressurised tank), and immersion-heated water is on tap again. I realise that I have to get used to the hot water now issuing from the taps at a similar pressure to the mains cold water – after 30-odd years of being accustomed to the hot water flowing at much less pressure. Various brackets and batons are fitted on the outside and inside of the roof ready for the panels.
Wednesday: more preparatory work on the roof, inside the loft, and in the house – piping, structural supports and wiring.
Thursday: clear morning, heavy rain forecast for the afternoon, so time to get the panels on the roof – all the hi-tech comes down to men with ropes! Extra workers arrive to provide more muscle (two men at the top with the ropes, two men on the ladder supporting the panel) – one panel goes up at the front and two at the back, and they’re bolted onto the brackets. Then there’s more piping to be done, and connecting up the different elements of the system. At the end of the day the system is tested under air pressure (hard work with a hand-pump) to ensure that there are no leaks, and that the safety valve releases at the required pressure.
Friday: Filling the panels and pipes with the heat-retaining fluid (similar to antifreeze that goes in a car radiator) connecting everything up, testing it, finishing off.

The scaffolding was supposed to be taken down on Friday afternoon, but it poured with rain and they didn't come - it was all removed early the following week.

The system works like this: the pipes feed down from the roof and into the bottom of the tank, where they form a coil (there’s no contact between the heated fluid and the hot water you actually use) – it’s a heat-exchanger. The sun heats the fluid in the panels, a sensor determines the temperature difference between the panel and the tank and sets a pump in motion; because I have east and west facing panels, they operate independently (because they will be at different temperatures from each other, depending on the time of day). With a south-facing roof there would be one sensor and one pump. An information and control unit tells me what is happening, if I want to know – but it’s perfectly possible to ignore it, and just use the hot water. On a bright but chilly day in mid November, the day after the installation was completed, the panels were reaching 30 deg C – not the full heat of normal domestic hot water, but a good way towards it, reducing the electricity needed.

If you have a gas-fired hot water radiator heating system, that also heats your hot water, then the solar-heated hot water would be plumbed into that system, meaning that, in winter, your boiler would have to work much less hard because it would be working on pre-warmed water. In summer, you’d get your hot water from the solar panels, with whatever you already have as back-up/top-up if needed. There have been some firms jumping on the bandwagon of solar heating and fitting cheap systems that disconnect your hot water from your central heating – this is because to do the gas work they would have to be Corgi registered, and they aren’t. The company that fitted my system has found itself doing lots of remedial work in the wake of ‘cowboy’ installers. So, please be encouraged by my experience, and think about this for your home. But find a reputable firm – if you don’t know anyone who’s had this work done, and who could recommend an installer, always ask a company if you can speak to someone they’ve worked for – if they’re good, they’ll have access to satisfied customers more than happy to speak to you. So if they won’t offer this, go elsewhere.

Final question – what did it all cost? Well, my east-west system cost more than a south-facing system would have done. I don’t know how my hot-water-only-system compares with panels integrated into the central heating. I paid about £6,500. I didn’t go for the government grants because I wanted to do this on my timescale, without any bureaucratic delays. Also, be aware that the system of registering contractors who can apply these government grant discounts keeps on changing. Every time they change the system, the firms have to register from scratch all over again – and every time this happens, they have to pay another fee to the government, in order to be listed, and it isn’t a small amount. So this has a disproportionate effect on smaller, local, family-run firms, such as the company who did my installation. It happened that they were in the ‘gap’ between one registration and the next when I approached them – but they came highly recommended, I had a specific time-window when the work could be done, so I went ahead with them, and no grant. I was fortunate to be in a position to be able to afford this – my mother’s death earlier this year meant that I had some capital sitting in the bank. At the moment, interest rates are so low, that the return on my capital has been increased significantly by putting it on the roof! What I will save in electricity to my immersion heater outweighs the paltry interest I would have earned. So it’s financially sound as well as green.

Below is a photo sequence showing my installation from start to finish. The company has more photos of other installations they’ve done on their website. For an account of someone starting from scratch on a green makeover, in an older and more difficult house than mine, here’s Madeleine Bunting writing in the The Guardian in September 2009.

The single panel to go on the front (east facing) side of the house, on the ground being prepared for hauling.

Half way up . . .

made it!

and fixed to the waiting brackets

a similar process at the back of the house, but this time there are two panels to go up

the whole team with both panels in place

the front view with the scaffolding gone

and the back similarly

The new tank - the lagged black tubes on the left are the insulated pipes carrying the glycol from the roof panels to the coil in the bottom of the tank. On the wall to the right is the control/information unit.

Here it is in close-up telling me that on a cold, dull November afternoon, the panels at the back of the house are at 19.4 deg C; and (below) the heat at the coil has reached 21.1 deg C

The last picture - here (up in the loft, and out of the way) are the pumps, pressure valves, expansion tanks, and other safety features:

I said, at the start of this article, I’d write a bit more about how we influence others by what we do. Coincidentally, in the same week I was having the work done, New Scientist carried an article about this very phenomenon. The reference for the paper edition is:
David Rand and Martin Nowak, ‘Name and shame’, New Scientist, 14 November 2009 (issue no.2734), pp.28-29.

The online version is: ‘How reputation could save the Earth’, 15 November 2009. Unless you are a subscriber, the link will only enable you to see the opening section of the article.

Early on, the authors write:
‘Environmental problems are difficult to solve because Earth is a "public good". Even though we would all be better off if everyone reduced their environmental impact, it is not in anyone's individual interest to do so. This leads to the famous "tragedy of the commons", in which public resources are overexploited and everyone suffers.’
And later:
‘Experiments have shown [. . .] that the benefit of earning a good name outweighs the costs of doing your part for the greater good, and even selfish people can be motivated to care. It is worth contributing in order to protect your standing in the community.
Out in the real world, these experiments suggest a way to help make people reduce their impact on the environment. If information about each of our environmental footprints was made public, concern for maintaining a good reputation could impact behaviour. Would you want your neighbours, friends, or colleagues to think of you as a free rider, harming the environment while benefiting from the restraint of others?
[This serves] a dual purpose. First, [it allows] those who contribute to reap benefits through reputation, helping to compensate them for the costs they incur. Secondly, when people display their commitment to conservation, it reinforces the norm of participation and increases the pressure on free riders. If you know that all of your neighbours are paying extra for green energy or volunteering on a conservation project, that makes you all the more inclined to do so yourself.
[. . .] In a world where each of us was accountable to everybody else for the environmental damage we cause, there would be strong incentives to reduce the energy we use, the carbon dioxide we emit and the pollution we create. In such a world, we might be able to avert a global tragedy of the commons.’
For another 'take' on this whole theme, on a wider canvas, you might like to look at a speech given by Archbishop Rowan Williams, 'Human Well-Being and Economic Decision-Making', on 16 November, to a conference organised by the TUC and The Guardian. He ends with a new version of 'the 3 Rs': revive, reflect, resist.


  1. I'd be interested to know whether you considered the Solartwin system rather than conventional Solar, especially as their installatuoj is much quicker, and their do not rely on mains electricity at all. In fact they have an entirely diffeent approach to solar heating.

  2. In response to Paul's question, I didn't look at Solartwin. I went for a local contractor, personally recommended by a friend, knowing that they would be on-hand for any future work.

  3. 20 December - a postscript: it's freezing outside, literally. Snow on the ground and the temperature hasn't risen above freezing all day. But it's bright and sunny, and the temperature in my west facing panel, at 2pm, is 20 deg C. That certainly reduces the fuel needed to heat water, instead of starting from the very cold water that is currently coming out of the cold tap.