Today we had a visit from the Notts Energy Partnership to consider whether solar hot water might work for us. They run a project called Sungain, which is about bringing solar hot water to as many homes as possible – and in the process drive capacity amongst local firms for putting solar panels on local roofs.
Just for good measure it’s the first properly sunny day for ages, so we could see clearly that the roof over our car port gets its fair dose of the rays – at least until 2.30pm when the sun goes behind the tree. Our house is oriented with the corners on the compass points, which means we don’t have a south facing roof, but a south-east facing one. This is less good, but not impossible.
It’s not a trivial job to fit one in this house. We already have a hot water cylinder based system, but at present our hot water is only used for hand washing and the little hand washing up we do. There’s neither the pressure or capacity in the current old cylinder to run showers, which would be the main point of embarking on something like this.
So to get solar hot water, we would need to
- fit evacuated solar tubes on the roof
- replace the hot water cylinder with a larger one
- relocate the hot water header tank to the highest possible point in the attic
- pipe the whole lot together
- replace bath taps with a mixer shower combo
It is quite a lot to do, and won’t be cheap. But in the context of some of the other things we are spending on the house it is an affordable cost. It’s not a great deal more than the cost of new windows.
There are still some things to weigh up.
- Pay-back time. This should give us cheap or free water heating for much of the year. Even over the winter, on bright days, the kit should mean the boiler has less work to do to get the tank of water up to temperature. But calculating payback will be complicated. It will mostly be electricity we save (no need for electric showers).
- Changes in the bathroom. Neither of us has particularly fond memories of the times we spent in homes with tank-fed showers instead of on-demand heating from an electric shower or system with a boiler that heats as you use. Don’t want to run out of hot water, or get scalded when loo flushes or washing machine starts. This is mitigated by the fact there’s only two of us, and we usually shower at different times of day
- Fitting a mixer tap might mean replacing the bath
- There’s a chance a yob with a rock could damage the solar tubes
- Fitting complicated things – or even just “different” features – might make it harder to sell
- Still more work to do on the house and plumbing!
On the plus side
- Low cost hot water, even when fuel prices increase
- A bigger airing cupboard
- Feeling better about banging on about sustainability issues in planning meetings
- Solar panel will improve house performance on energy performance certificate element of home information pack
- Watching the control gizmo, which monitors the temperature of the panel and the temperature of the hot water tank, and switches on the coolant pump whenever the panel is warmer than the tank, will appeal to my temperature nerd elements 🙂
EDIT: Good grief, a bath/shower mixer tap costs over £100, according to B&Q website!
Niles's Blog 
Fitted Beasley Centurion 315 a year ago. 4 sq m twin panels. Mains pressure, removed LP header tank and 180 litre hot water tank. Useful cupboard space. Cost $7,500 (NZ) materials only. DIY. Saved $290 (NZ) in year. 4 months of summer no power cost. If I live to be 99 (Now 79) I may see a return. Meanwhile monthly power bills reduced. Worth it? marginal, but I feel good. Your pros and cons above, agreed. Roof orientation N 25 deg E. Pitch 25 deg. Latitude 41.4 deg S. Picton NZ. Insolation very good. Oceanic climate and clear air. Being elderly we have savings which we can use to ease our days. Bathroom underfloor heating. Quite cosy now. Even now the cost has been forgotten. Now winter in NZ, still can save 20 Kwh in month.
Thanks Alexander, that’s interesting. I suspect our economics and circs might mean pay back before we’re 90! Hadn’t occurred to me that that southern hemisphere solar panels would need to point north!
Other comments to this elsewhere on CIX have made suggestions that B&Q are very expensive for taps, and this suggestion, and particularly this one on Screwfix might be more affordable.
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I have just purchased an 80 watt solar panel for my workshop to run small things like lighting and power tools. Have I done the right thing? Are solar panels really worth having?
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