Nuclear power , not that cheap or safe it appears

It’s great that you are in that position, but for the majority I suspect the financial aspect of installing solar heating, insulating a home etc is a fairly important factor.

Come off it. This forum is filled with people agonising over which new £3000 bike to buy.

I’ve had a good look through the Energy saving Trust site, Ransos. The only reference to £55 I can find is the figure given for what you can save by properly insulating your hot water tank and lagging the hot pipes. Now if you can save £55 I suggest the total typical consumption figure must be somewhat higher. Could you link your source please.

Come off it. This forum is filled with people agonising over which new £3000 bike to buy.

What does that have to do with the demographics of the UK?

I just don’t see that financial payback is relevant (unless you don’t have the money) – the main thing is that it makes sense in carbon terms.

Solar thermal saves only a small amount of gas. Gas produces 1/3 of the carbon electricity produces per KWh. So I don’t think it makes much sense in carbon terms, either.

I’ve had a good look through the Energy saving Trust site, Ransos. The only reference to £55 I can find is the figure given for what you can save by properly insulating your hot water tank and lagging the hot pipes. Now if you can save £55 I suggest the total typical consumption figure must be somewhat higher. Could you link your source please.

http://www.energysavingtrust.org.uk/Generate-your-own-energy/Solar-water-heating

“Based on the results of our recent field trial, typical savings from a well-installed and properly used system are £55 per year when replacing gas heating ”

Insulating your loft/roof is a no-brainer really.
In the grander scheme, we need to be reducing electrical energy use.
Not only is it more expensive, it’s a good bit more carbon intensive. Look at your lamps (there’s a variety of CFLs on the market with different start up times and CCFs so do some research and buy the correct type for you) look at appliances, plug-top timers are cheap and easy to set up, buy AA+ rated kit.

http://www.energysavingtrust.org.uk/Generate-your-own-energy/Solar-water-heating

Your link Ransos, sorry it’s in full, the buttons have vanished to link it. I know how much hot water three very economical people use and a saving of only £55 is nonsense. It assumes the solar water heater only contributes 20% to water heating which anyone who has used a solar hot water heater will tell you is wrong. They (Energy Saving Trust)reckon you can save as much just by lagging your tank.

Edit: I found it eventually. 🙂

We’re currently having some walls internally insulated as part of a refurbishment project and I haven’t even bothered to work out the extra financial cost – it probably won’t pay back in pure financial terms

If you’re doing it as part of a bigger project it might well payback, because the trades are all onsite anyway. The other benefits are a more pleasant home environment and reduced mould/ condensation.

I haven’t included the photovoltaïque which will pay for itself in 6.5 years.

Thank god for that, because if you had I would be asking:

Where were the working bits of the PV made? (I’d guess either somewhere like China or Japan). How do you make silicon (or CdTe if they are of that form). Its not exactly a low energy process. Panels roughly “break even” on energy (in terms of kWh required to produce the panel) in something between 2 and 8 yrs depending on the panel design and the latitude its mounted at. Paying for itself financially and in energy terms is not the same thing since there are better rates for PV. But here is the point people seem to miss: if the panel was made in China it was made using dirty coal power. So the global environmental impact of making the panel is much worse than using clean coal (or other western power) in Europe for the entire payback period. If the panel is Japanese in origin then it almost certainly relied heavily on nuclear power to make it – which most of the people who fit them seem uncomfortable with. In addition, for reasons nobody has ever explained PV panels are exempt from ROHS regs and so potentially a “disposal timebomb” full of lead, cadmium etc…

Whilst over a 20+ yr lifetime of a panel it will save energy they aren’t ‘saving’ energy from the day they were installed due to the invested energy within them. Financial investments, recovered over several years may make sense. I’m not so sure that makes sense for carbon.

Quite frankly PV panels, certainly in the UK are just Eco-bling.

I know how much hot water three very economical people use and a saving of only £55 is nonsense.

This was the result of a field trial. You’re confusing evidence with personal anecdote.
Here’s my personal anecdote, which is the opposite of yours:
My last two quarters’ gas bills were a total of £85, no heating was on during that period. From my annual non-heating total of £170, we subtract gas for cooking and the inefficiencies of the solar panel (let’s assume it provides an average of 50% year round, and we use say 20% of the gas for cooking). Then we subtract the cost of the electricity for running the pumps.
£55 is absolutely spot on.

What does that have to do with the demographics of the UK?

Sod all.

But so what?

I just kind of took it for granted that I was addressing the users of this forum, not the nation as a whole.

these threads are like some kind of stw hormone cycle that comes around every couple of months. I don’t have the energy (wahey!) to get involved in them any more.

Poly he is further south but I tend to agree with you – photovoltaics are not really a part of the solution in the UK at present efficiencies / manufacturing cost / lifetime environmental penalty

Taking 50l/person/day from here thats 200l per day for a family of four, or 73 000l per year.

start temperature of water is 10°C. Final temperature 50°C, change 40°C
Q = 73000 x 4184 x 40 = 14966168000J
= 4157 kWh (assuming perfect lagging and no heat losses.

At 8p per kWh that’s £332

The Energy Saving Trust either can’t do maths or think that solar panels provide less than 20% of hot water needs.

You aren’t going to get water at 50°C for more than a couple of months in the UK. Average winter temp is 4.4°C and our winters are loooong.
Gas isn’t 8p/kWh, more like 4 or 5p/kWh.
Regardless of insulation, there will always be heat losses.

The Energy Saving Trust either can’t do maths or think that solar panels provide less than 20% of hot water needs.

Your calculation is irrelevant. It’s a theoretical example for a specific case. By contrast, EST did a proper field trial. When you’ve done one of those, come back with the results, and we can discuss it.

In any case, your savings calculation is way off. It’s nearly double the total amount of non-heating gas I use in a year. Family of 3.

My Solar World panles were made in Germany as was the rest of the system. They’ve already paid for themselves in embedded energy terms.

Using your own figures Ransos. £170 for the year based on summer hot water and cooking use. I assume you have a couple of weeks holiday and the water takes more heating in the winter. Say £190 per year for hot water and cooking and you’ve forgotten to add in the water heater in the washing machine (and dish washer if you have one) so we can add another £20.

£210 – 20% for cooking = £168. 70% produced by solar = £117

Using your own figures Ransos. £170 for the year based on summer hot water and cooking use. I assume you have a couple of weeks holiday and the water takes more heating in the winter. Say £190 per year for hot water and cooking and you’ve forgotten to add in the water heater in the washing machine (and dish washer if you have one) so we can add another £20.

£210 – 20% for cooking = £168. 70% produced by solar = £117

You really should stop making assumptions. No holiday this summer. Year-round efficiency of solar panel likely to be less than 50%. Dishwasher and washing machine are cold fill only, like most of the population.

£170 year-round less 20% cooking = £136. Less 50% efficiency (optimistic) for panel = £68. Less electricity for running the pumps, let’s say £10 = £58.

£58 against the EST figure of £55. Time you learned to add up…

I’ve done a proper field trial too with a system designed by a bunch of solar fans and plumbers on a forum.

It uses two tanks:

the solar tank heated only by a heat exchanger fed from the solar panel. The system thermosyphons as the tank is above the panel, thus requiring no pumps or control gear and eliminating risk of back-syphoning. It’s all double lagged. The solar tank feeds the house direct in Summer (six full months this year).

The second tank is a small (50l) conventional tank with an immersion heater. In Winter the water pre-heated by the solar tank enter the second tank and we switch on the immersion heater as needed. Most of the heating is still solar except for a month either side of the Winter solstice.

I know many commercial sytems use only one tank, are insufficiently insulated, run energy greedy pumps and simply don’t deliver their promises. However, I feel an organisation such as the Energy saving Trust should base their findings on a system at least as good as a monkey with blow torch can cobble together in his shed.

Should EST base their study on a) a custom-designed highly unusual system or b) the type of system most people have or would buy?

Even if your system supplied 100% of my hot water, it would still only save £136. If a typical installation costs £4,800 (EST figure) that’s a 35-year payback! So a more typical installation is perhaps a 70-year payback. Wouldn’t that be longer than the operational lifespan of the equipment?

Carbon saving is also low.

Another round in circles argument in which you criticise me for using my own system as an example then use yourself as an example of energy needs and pick a 50% figure out of fresh air for solar hot water heater contribution.

The Energy saving Trust is not usuing accepted levels of hot water consumption as reported by many government and non-government organisations. I suspect the system they used only included one tank and the temperature selected meant that the solar panel hardly ever circulated in winter.

The Energy saving Trust is not usuing accepted levels of hot water consumption as reported by many government and non-government organisations.

No, they’re using what happens in the real world. Because they’ve measured it.

I used my own example because the plural of anecdote is not data. Your example is worth no more than mine, which is why we refer to independent studies.

Ransos,

Do you not see the general problem in arguing that the theoretical output of a system is a more reliable measure of it’s efficiency than the actual measured output?

which is why we refer to independent studies.

Which probably aren’t worth that much either. 😆

From CIBSE;

8.3 Payback times
8.3.1 Economic payback
The simple economic payback times (the time in years taken for the cost savings to offset the initial capital cost) for some swimming pool heating systems and air source heating systems can be under 10 years but, in general,the payback times for photovoltaic and solar thermal systems are long and may be longer than the lifetime of the system. However, these estimates do not include potential fuel price increases and any grants or other incentives that could reduce the payback times substantially. The installation of a solar
system may also increase the value of a building.
8.3.2 Energy payback
The energy payback time (the time needed in years for a system to
reimburse its energy content) is between 2 and 4 years for solar thermal systems and between 3 and 5 years for photovoltaic systems, depending on location and whether it is roof or façade mounted.
8.3.3 Carbon payback
The carbon payback (the time needed in years for a system to offset its carbon content by carbon savings) for solar thermal systems is about 2 years and for photovoltaic systems between 4 and 6 years, depending on the technology used.

Capturing solar energy
CIBSE Knowledge Series: KS15, 2009
If anyone wants a copy, let me know.

Do you not see the general problem in arguing that the theoretical output of a system is a more reliable measure of it’s efficiency than the actual measured output?

What matters is what happens.

Which probably aren’t worth that much either

Trans: I don’t like what they found so I’ll call it rubbish”. 🙄

People can spec and buy the system they want. People buy and spec the car/bike they buy and don’t always make a sensible choice as this forum often demonstrates.

The Energy saving Trust is there to advise and should therefore do some research and spec an efficient system that they can then advise to people viewing thier site.

You can buy a system that relies on using electrically heated water to prevent freezing (a colleague of my wife was horrified to find that was how his expensive commercial system worked). You can buy systems based on thermal stores and pumps which at have anti-retun valves and anti-freeze in the primary circuit but don’t circulate much in Winter. Or you can buy a system that serves as a pre-heater so provides all your Summer needs and makes a good cntribution in winter. The EST (I’m getting tired of typing Energy Saving Trust) should spec a system that is capable of saving more than it says lagging a tank will.

Trans: I don’t like what they found so I’ll call it rubbish”.

Like you’re doing?

From CIBSE

in general,the payback times for photovoltaic and solar thermal systems are long and may be longer than the lifetime of the system

Which is what I’ve been saying…

By all means install solar thermal if you want to, but don’t kid yourself that it saves much money or carbon.

ransos – my parents got well more than that from their system -payback was around 15 years. Got the water hot enough to use some of the time and the rest gave a significant boost as preheat. Sophisticated system allowing it to be used direct or as a preheat. Installed in Scotland 20 years ago – modern systems should be better

The Energy saving Trust is there to advise and should therefore do some research and spec an efficient system that they can then advise to people viewing thier site.

The purpose of the report was to determine the effectiveness of systems in the field. That’s what they did. The results may be taken as advice that typical systems don’t save much money or carbon.

Hopefully, the results will motivate the market to do better.

Power stations are very expensive to turn up/down

With the exception of gas-powered stations and pumped storage stations.

“in general”, what mean “in general”?
What mean “for some swimming pool heating systems”?
What mean “However, these estimates”?
These are the statements that mean independant reporting is vague not some smartarsery comment.

ransos – my parents got well more than that from their system -payback was around 15 years. Got the water hot enough to use some of the time and the rest gave a significant boost as preheat. Sophisticated system allowing it to be used direct or as a preheat. Installed in Scotland 20 years ago – modern systems should be better

I’m happy for them.

“in general”, what mean “in general”?
What mean “for some swimming pool heating systems”?
What mean “However, these estimates”?
These are the statements that mean independant reporting is vague not some smartarsery.

Trans: I don’t like what they’re saying so I’m reduced to nit-picking.

Tell you what. You convince yourself of whatever you like. I’ll stick with the evidence from reputable sources.

Trans: I don’t like what they’re saying so I’m reduced to nit-picking.

🙄

Maybe we could create a computer model of a central heating system taking into account all the known feedback cycles and predict how hot the water will be? 😀

42?

I’ve already quoted the price of my own system, 1100e. The biggest double-glazed Velux window I could buy (non reflective glass), 25m of 18mm copper pipe and fittings, insulating materials, a 150l tank with an exchanger coil, some fittings and welding gas. My own hot water consumption I estimated as around 150e (similar to yours, Ransos) and last year it was down to less than 50e (I’m assuming all excess Winter electricity consumption is down to hot water when in fact it’s also down to more lighting, Madame baking etc..)

So even in economic terms I get my money back in 11 years. No boiler to service, no standing charge, no pumps, no electronics, low depreciation. Nothing to do apart from clean the glass now and then.