Domestic solar panels

Bruce
For information go to the government web site "clear-skies". This is mostly for hot water systems.
Although you have a combi system, this might not prevent you using a solar heating system for your hot water, pressurised tanks are now available.

There is also the "green energy website" which also includes info on photovoltaics . At present efficiency rates, you will need a considerable surface area to gain much power.

When considering solar power, check on your local authority planning requirements. If you live in a listed building, AONB or consevation area you may encounter restrictions.
The consevation area bit got up me, as conservation is one of the main reasons for employing renewables. We live in an AONB and the panels required planning permission similar to a roof window. Apparantly such panels are judged an eyesore in a similar vein that mobile 'phone masts aren't (irony).

Good luck and don't get taken in by the claims of some traders, there products are no better than those available to the DIY'er, and are quite extortionate in comparison.

Cheers

Marvin

Lots of good info and links at

http://www.cred.co.uk

I believe you can now sell excess electricity to the grid - though for less than you buy it for.

Regards

Stephen

Bruce,

I suspect that domestic photo-voltaic cell electricity generation in the UK is not particularly cost effective. Cost of solar panels is high relative to the output plus the number of 'quality' hours of daylight - i.e. with the sun reasonably high in the sky and not too cloudy, is rather low. Especially during the winter months.

What we do have in abundance in this country is wind! Plenty of it, day and night, all year round. If you do the comparison I'm sure you'll find a wind turbine to be more cost effective. Siting is more of an issue though and needs a bit of consideration in terms of noise annoyance - yourself and neighbours. Planning permission is a bit of a gray area and may or not be necessary depending if the construction is regarded as temporary or permanent.

Regards,
Allan

Bruce

We had solar tubes fitted this year, but only to heat water, rather than make electricity. For that they are pretty good, even today they have raised the temp of our tank to 42C, and the good afternoon sun is still to come.

However I'm in Leicestershire and I expect in North Yorks you would do a lot less well.

Ecomonically at £3500 to fit you aren't looking for an instant profit and I think the generating type are significantly more expensive. We had them fitted to feel we are doing our bit for the environment.

If you want to make electricity I too would consider wind. There's plenty of that available to you 24h a day!

Guy (? a fellow Copperfield fan)

A factor that might be worth taking into account is solar panels' lifespan, which I vaguely remember may be seven to ten years.

Solar tubes sound interesting. Are they attached to the roof or do they replace sections of roof?

To be fair solar panels arn't exactly nice things to look at are they?

Thanks for the information so far, I'll start doing some reading etc.

Guy D-can you just clarify how your system integrates with an existing hot water supply-do you have an independent tank for the solar or does it augment a timed immersion heater system?

Must admit I think that solar panels are not so ugly. Not compared to a power station anyway (or our enormous Calor gas tank).

Bruce

Normally you use a 120litre (legal minimum here) DHW cylinder with double coils. One coil circulates from the CH boiler and the other via the panels on the roof/garage. Obviously you must have a clear south facing roof or other suitable structure for maximum solar exposure. (No light blocking trees) A suitably sunny geographical location helps too. Check annual cloud cover figures with your local meteorological office.

Bruce
The solar collector is integrated into the hot water system thru a replacement tank, as it need another heat exchanger
Depending on the system bought, you get either a solar powered pump or an electric pump.
The collectors now are exacuated tubes, with a reflective backing (termed 360 degree tubes) that are much more efficient - stated to be up to 96% - than the old flat panels. They heat the water in the cylinder via a 'fluid' that is effectively an anti-freeze, enabling them to be used in scotland all year round. The pump will operate if there is a temperature differencial between thetank and the collector.

Lifespan is not quoted, examples of the old flat panels exceeding 15 years old and still in effective operation are given.

As to cost, the cheapest DIY system I've seen on the net is around £1000, however this is probably just the collector. A company called twin panel has been in operation for several years, they are quoting £2500 for a complete DIY system including solar pump. Apparantly the main advantage of an electric pump is a quicker reaction time.

Good luck, ans as far as I'm concerned they are not as ugly as the nuclear power shell at Transfwryd, which will be there for my lifetime at least. But beauty is in the eye of the beholder afterall.

Cheers

Marvin

quote:

Originally posted by garyi:
To be fair solar panels arn't exactly nice things to look at are they?

I think they look very cool.



Stephen

We do not currently have a water tank, we have 'instant' hot water via a combi boiler. I'm struggling to work how these two systems could be combined, and we are not wanting to change boiler as it is recently installed.

I'll chat with the plumber and some specialists.

Bruce

quote:

Originally posted by Bruce Woodhouse:
We do not currently have a water tank, we have 'instant' hot water via a combi boiler. I'm struggling to work how these two systems could be combined, and we are not wanting to change boiler as it is recently installed.

I'll chat with the plumber and some specialists.

Bruce

I'm in the same position as you - no space for a boiler.

Let us know how you get on

Regards

Stephen

Solar panels are sooo last season. What you need is a wind-farm.

Bruce

We have 22 tubes on the roof each about 5cm diam and a meter long. In our system they directly heat our hot water as opposed to some other systems which heat a fluid which then has a heat exchange system to the hot water. We have a single hot water tank. It has a pump to circulate the fluid up to the roof and across the hot ends of the tubes (all insulated to -20C). There is a sensor on the roof and in the tank. When the temp differential is >6C the pump cuts in and heats our water. One way valves stop heat loss to the roof.

We have the option of either gas or emersion heaters to heat the water when there is insufficient sun to raise the temperature to what we want. Having an accurate thermometer on the tank makes this a simple task. We tend to do any additional heating at the end of the day and then use the hot water in the evenings. We start the day with a coolish tank to maximise our solar benefits.

The tubes are maintainence free (apparently having trees over the house can lead to algae build up, secondary to bird shit, but it is not an issue for us). The life of the tubes is expected to be around 30 years.

Guy

Bruce,

You might want to take into consideration that electricity costs per unit are about 2 or 3 times higher than that of gas. (Although today's news about gas costs might close that gap soon). Therefore the payback period of putting in measures that reduce your gas consumption is going to be that much longer.

For cost effectiveness, your first priority should be electricity. You may just want to take an altruistic view and simply do what you can. However, you also need to keep in mind the total life energy cost of whatever devices you are fitting. If the total energy costs of manufacture and disposal outweigh the total energy saved (because, say, it is inneficient/innapropriate in your situation) then you're not really saving the environment.

Actually, the most cost effective thing you can do is look at where you can make energy savings in your house. Things like changing a CRT monitor for LCD, Use A* rated appliances when due for renewal, etc. I did a simple calculation like this for myself and realised that the cost of making these efficiency measures is about a third of what it would cost to generate your own electricity - i.e. saving 1Kw/hr by being more efficient costs about a 1/3rd of what it would cost to buy equipment to generate that 1Kw/hr.

Regards,
Allan

Thanks to all the contributors. A bit of feedback.

Several specialist installers have said we would need to switch to a conventional (rather than a combi) boiler to have a hot water system. The alternative would be to have a stand alone electric immersion heater augmented by solar but this would be a clumsy way to run it and probably not very economical. The existing (and fairly new) combi may ultimately be less wasteful.

We are actively looking at better efficiency at home, although actually have quite low electricity bills I'm sure we can do better.

As for the unit cost of electricity vs gas, a good point. However I have a feeling that the Calor Gas we run on brings the gap down somewhat.

I'd also recommend the clear-skies site as a good start for anyone else thinking of looking at solar.

Bruce

Bruce,
One small idea that may not work as well for you as for us in Spain, is using solar water-heating panels to pre-heat the cold water feed to your combi - it is easy to install, and results in us using far less gas to heat our water, though if it will be cost effective in a less sunny area is unlikely, I guess.
I bought from a company called Magpie Technologies, and dealt with a guy called Stuart - stuart@solaruk.net - I have no connection or even any idea if they are good or better than other companies, but we had no problems !
We also use bottles gas, and I reckon we use about 80% less with the solar assistance !
Good Luck,
Steve

That is an interesting idea, thanks.

May follow it up with your supplier.

...or move to Spain

That's not a bad idea either - As I write, it is sunny, and whilst cool, if in the sun you can be in shorts - and just how foggy is North Yorks today..
But I do miss the drizzle at times.
Yup.

I have found the following book written by architects with an interest in green buildings to be accessible. It has a comparative perspective showing how solutions have been developed for different climates, with case studies of some example buildings. There is coverage of solar electricity generation, passive solar heating and solar water heating including cost-effectiveness calculations.

Ecohouse 2, A Design Guide.
Editor: Sue Roaf Contributor: Manuel Fuentes Contributor: Stephanie Thomas.
Architectural Press, July 2003, Second Edition


Nick

In the stupid suggestion category - you mention elsewhere that you live by a canal - this is a huge store of heat energy - can you extract heat from the water using a heat pump to heat your own property -

It may be snowing where you are but in Leicestershire we're making hot water!

Guy

Hi,

I have done a lot of research on this topic. Best cost effective solution is solar assisted water heating. You can expect to cover most of your hot water bill for about 5 months of the year, some for 4 months and little in winter. Solar generated electricity is very expensive and not cost effective. The panels are expensive but that isn't all the cost. Special wiring, invertors, batteries which need to be replaced inside 10 years. As an eco solution, a combination of solar water heating (summer), wetback water heating (winter), solar electricity and wind generation would work. The cost in this country to power an average 3 bedroom home is about $50,000 NZD. (£20K) That's a lot of power bills. Solar water heating makes sense, the rest will take a brave heart.

Chris.