This isn't strictly diy but I hope it will pass muster. I have googled for hours and am now thoroughly confused. My mum lives in Devon and her house has oil fired CH & DHW plus an immersion heater. Boiler is a Grant and 1 year old. I pay all her bills. Mum is a blind octogenarian and I'm not far off the bus pass. CH and DHW are on a 7 day programmer which operates all year. Immersion only used in the event of (frequent) power cuts.
She has a south facing roof that might be ideal for solar panels of some kind. I checked today and this roof received full sunlight from approx.
08.15 to 18.30. I'm thinking that the price of oil is not going to go down significantly and that some form of solar heating might (1) help to alleviate the current heating costs and (2) add some value to the property when she goes pushing up daisies. I realise that the cost of supplying and installing will be considerable but hopefully these could be parly offset by 1 & 2 above. There is no space for ground source heating. So I'm guessing that water or pv panels are the only viable solution. Any thoughts/comments/ideas please.
The subject always brings the have nots out of the woodwork but there are two useful things to consider doing.
to install a solar collector hot water system which is an effective way of heating hot water in the cylinder and once commissioned runs unnoticed, making hot water all year but obviously the effectiveness depends on the seasonal intensity and duration of the sunlight falling on the collector. My system raises the cylinder temperature part way to set point in winter and the oil boiler tops it up from that temperature to "hot" at tea time on a timer which I can boost at other times if I wish. In summer the solar input raises the hot water to full temperature and the oil boiler does not cut in at all most days. I installed my own system with a =A31000 kit of parts including a new cylinder a few years ago and it has run without intervention since. If you go for professional installation an incentive tariff is now in existence provided the installer is registered under the scheme.
(Most systems have the collector panel higher than the cylinder so do not operate if there is a power cut - you could install a small pv water pump if the number and duration of power cuts is significant)
Solar electricity generation usually creates a cacaphony of howls from the usual suspects in here but do the maths and get signed up to a Solar PV Feed In Tariff before next Easter. This will produce an income of 43.3 pence for every unit of electricity generated AND if you are able to use the electricity you have just made instead of it going out to the grid (exporting) you get to use it for NOTHING. So you can run your oven during the day to cook etc and if the rate of generation at that time (lets say for argument on a day when the panels kick out 2.5 kW) is not as much as your oven for example consumes (say 3kW) you only pay the supply company for the balance of
0.5 kW. At present the electricity companies are assuming that 50% of your FIT generation will be exported and 50% you will use yourself. With this figure in mind they pay an extra 3 pence per unit for half of the units recorded on the total generation meter of you Solar PV system. If you study the effective return on investment it makes sense to borrow at a suitable fixed rate then sit back and let the price of electricity carry on rising knowing you are buffered from a significant part of it. The income is tax free and what you make in the summer can be used to offset the cost of winter consumption. Note the generation in winter is very low! The average over the year is what counts.
Note also that a solar pv unit will shut down if the mains goes off and restart when the mains is re-energised.
You do need to make sure that the life expectancy of the owner and family are likely to be sufficient to warrant the outlay. (In my case the kids will likely see more of the longer terms benefit but I see that as a worthwhile legacy).
My IMHO is quite clear on this, although not mainstream. In My Copious Free Time I'll be putting the money in my mouth and doing two of these systems myself.
Solar thermal is workable. However it works best for delivering low temperature warm water, not hot water.
Heating costs money. However your spend on space heating far outweighs that spent on hot water.
Solar system cost can vary. Vacuum tubes are now much cheaper than they used to be, but a half-decent stratified thermal store will still cost as much as the rest of the system.
You can't heat a UK house in the winter, on solar alone, unless you also have hyperinsulation (probably designed in as a new build), big panels and a lucky climate. So if you can't _remove_ the fuel-driven heating system, the game is now about cost savings, not about the absolute performance achieved.
So IMHO, go cheap and forget about hot water. Cheap system: panels, pipes, pump and heaters. No storage. Ideally go for underfloor heating and ignore heat storage in the water altogether, in favour of a massive concrete or tile slab over good insulation (That does of course assume some building work is going on).
This system will not perform as well as a more complex system might do. However it will cost half as much, require less installation space, and in terms of cost saving, I strongly suspect it will perform nearly as well. It will certainly have a far better return on investment.
So at best no more than 10 years left, probably less.
That's a neat trick. Can you pass on the secret?
(1) As others have said space heating is not viable in the UK from solar. Well not unless you are going to dig up the floor and fit under floor heating and add huge amounts of insulation to the building. Digging up the floor and/or replacing a suspended floor with a solid one won't be particulary cheap. I can't see how Mr Dingley can justify his "cost half as much" statement.
It should be possible to install a system that will supply all the hotwater requirement for a "little old lady" for a significant part of the year. This will produce some savings in oil but most oil will be being burnt for space heating.
(2) It might add a bit but not a lot. Less than the cost of the system. There would also be problems in system design, one designed for the HW demand of a single person would be grossly under sized for a family. One could install and oversize system but then it will probably "stagnate" to often and one wouldn't get the same return as properly sized system. No easy answer to that one. If the property was suitable for a family I'd go for a "family sized" system and keep an eye on the stagnation. Either by having some means of dumping the heat or just monitor the condition of the glycol mixture circulating through the panel(s).
The Renewable Heat Premium Payment scheme will give more return in the first year than the savings in oil. The RHPP is a one off =A3300, there are a few strings, like the system has to be installed by an accredited installer, no mains gas available, 250mm of loft insulation and cavity wall insulation (if practicable). Though why the later two are required for a HW system I'm not sure but this is all a bit technical for politicians to understand...
A system that complies with the RHPP scheme would also be eligable for the Renewable Heat Incentive payments if/when they ever sort of the details. That is due to start autumn 2012 and is rumoured to pay
18p/kWhr. So a solar thermal system in mid summer could earn a couple of quid/day plus the savings on not burning oil. Not a great deal but better than nothing.
As to costs a simple cylinder replacement with a solar cylinder, panel(s) and pump unit I'd expect to be =A32000 or less.
How does the immersion work in a power cut? (or am I missing something here?)
You can do ground source with a bore hole - that only needs about a square metre of space (and lots of depth!) Viability will depend on the local geology though.
Depends on what you want to achieve...
Solar thermal for heating domestic hot water is relatively easy, however the actual cost of a single person's hot water for a year is far less than most people expect. So the financial savings are small (probably under £100/year), and unless you DIY a system from scrap unlikely to ever payback financially (commercial systems are often well in excess of £2500, and unlikely to payback in their lifetime).
Solar thermal for space heating is more likely to payback in real terms, but rally needs a heating system well suited to making good use of lots of warm water rather than hot water. So well insulated places with loads of UFH etc work well, as can large (and expensive) thermal store systems where the solar can be one of many contributors of heat to the system). With the changes in legislation coming along you may also be able to get some financial incentives for installing something.
Solar PV currently makes the best financial sense (even though its probably environmentally hostile in real terms in the UK at least), since the effect of the Feed In Tariff schemes, generate a better rate of return than you are going to get from a savings account at the moment (a decent system ought to be able to generate over a grand a year in FiT payments). You will also potentially offset some electricity purchased by using your home generated supply - but again that is unlikely to be more than £160/year.
In terms of security of supply, none of them really help much. The solar thermal hot water heating can be made totally passive with a small solar PV pump to shift the heat, but it adds cost and complexity to an already expensive system.
Solar thermal heating will depend on mains electricity for pumping. Grid tie solar PV will shut down on mains failure (to prevent back feeding the grid) - not sure if any are sophisticated enough as yet to allow local generation and use when isolated from the grid.
Some form of backup power supply may be able to keep a solar thermal system going independently of mains. Solid fuel burners will usually be able to run hot water without mains power, although space heating is harder to keep going.
Its probably only worth only looking at any of the alternatives once the house itself has been insulated all round to a reasonable standard, since you can bite big chunks of energy bills in a low tech and relatively permanent way.
Heat pumps can make good sense where there is only electricity and no oil or gas (or for places where you want air con as well for some of the year).
During summer gas costs less than £12/month here, for a little cooking and heating a "normal sized" H/W tank twice a day, even with an ancient cast iron lump of a boiler and its pilot light.
Most days the second tankful is hardly touched, due to the big lump there's not much less gas burnt to reheat a warm tank than a cold one, but I like H/W on tap in case it's needed and I like the big old lump, hardly breaks the bank.
My elderly mother has such a lump too, and interestingly has been advised by the guy that pops in occasionally to maintain it, that she should hold onto it. This is despite the fact that she is well old enough to qualify for money for a modern replacement.
In 20 years (that I've owned the house, it's older than that) it's needed one new thermocouple, an occasional hoovering and half a tub of fireclay to replace a peeling seal, that's it.
Solar PV doesnt have a prayer of ever paying its way on houses that have mains. FIT payments might or might not change that.
Solar thermal doesnt normally pay its way. It is possible to design a system that will, but it requires skill, and professional systems have about zero chance of ever paying for themselves.
Solar systems dont add sale value to houses. Theyre trivial matters compared to what the buyer really cares about, and from a buyer's perspective there's as much chance that it will cost to rip it out and make good as that it will work and save a few quid.
If youre looking for financial viability, spend it on insulation. Generally the ROI is hard to beat.
They may well add value if you are selling the FITs to the new owner. What value is debateable as there aren't many examples to go by.
Didn't the government say they were going to have a "fits" scheme for solar heating next year? I also thought it was going to include ground source and air sourced heat pumps.
It makes a lot of difference to the economics.
Insulation has the big advantage of being good even if you don't believe the cr@p about global warming.
Who said that? All-year space heating isn't viable, but otherwise space heating is not only workable, but it's cost-effective too.
I see year-round as technically impractical, HW as cost vs. return - impractical.
I'm not advocating digging up a floor _just_ to install solar underfloor - however you may be planning to dig that floor anyway, for other reasons. I'm planning to take the whole roof off too from our rear kitchen extension, but that's for a big building project, whereupon it's a great opportunity for underfloor solar. In the bungalow, I want a new floor to remove a couple of steps on accessibility grounds.
That's half as much for a purely spaceheating solar system vs. a space and HW system, with a competent wet thermal store. If you aren't underfloor, you can still use radiators.
So design an expandable system. You can design for a family-sized panel area, but not install all of them. Besides which, when have you seen a pensioner complain it was too hot?
I can save =A3300 more easily with a phone call to a better installer than I can with RHPP from a "sworn deputy", an accredited cowboy who's just the same old bandit with a star on his stetson.
I'll be amazed if you can achieve that price. You can pay =A32k for the cylinder alone.
is due to start about this time next year but no details for the domestic sector have been finalised.
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has solar thermal at 8.5p/kWHr *rumours* had the doemstic tariif
10p higher. Personally as this money is government money not a levi on electricity bills like the FIT scheme I can see that the rates may well fall dramatically and/or the scheme "modified" in such away as to almost negate the word "incentive" in the title...
Others have commented at length on the economics. My tuppeny worth is that If it were my blind octogenarian mother I would not consider disrupting her life by having major work like this done on the house.
Far better to spend money on a bit more fuel for 5 -10 years.
But things like basic draught proofing and possible some careful insulation are far less disruptive and will have far more effect. Even putting up decent double lined curtains is a boon.
Aye, insulation is relatively cheap. Draught proofing is very effective, particulary around any external openings. This place would be almost impossible to maintain at a sensible temperature even with it's 38kW boiler without the draft proofing(*). OK we are exposed and at 1400' (it's currently F7 to F8 outside) but the same applies elsewhere.
(*) That starts with porches on all but one external door, both doors draught proofed, draft proofing around any of the old timber window openers, two sets of medium to heavy lined curtains at each window (one set by the glass the other outside the reveal). All little things that do add up.
The disruption that even the installation of a simple solar system would cause to a blind 80 year old does need to be taken into consideration.
My 80 year old would have seen it as the most interesting thing to have happened for months - provided they could stay in their own home, whilst it went on around them.
We're over 70 and didn't find either solar water heating or pv panels disruptive.
The combination of these gadgets and a wood burning stove, on which I cook when it's lit, have meant that the Winter Heating Payment pays our full gas bill for the year and the FIT payments will pay our electricity bills.
Not that payback was the reason we did it, as someone here said, we wanted to put our money where our mouths are. We don't think of payback when we open a bottle of wine ...
As someone else said, the most important asset is insulation - loft, walls and effective double glazing. That means that the central heating can be controlled by thermostat and set low.
Heat exchange is really only viable for newbuild, it would be hellishly disruptive in an existing property.
Alas payback is the only significant reason for investing in most of these micro generation schemes. Most are of questionable value for saving the planet.
If the thermostat is working, you should not need to change its settings. All that will happen is the heating will run less to maintain the temperature!
Does not need to be. A borehole system need not be disruptive to install, and if you already have a thermal store or some other way of aggregating the heat from it, it ought not be too disruptive elsewhere. The main problem is that they need electricity to run, and even with good COP may only equal gas for heating in cost terms. So worth looking at if you have no mains gas, but probably not worth it otherwise.
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