> Yeah, pull the other one!

I hadn't mentioned coal until trying to explain why Sandy was talkign about it to you.

But whatever, at least you seem to accept that the Germans are turning their backs on renewables and burning more coal.

http://euanmearns.com/merkel-snubs-global-warming-and-dumps-the-solar-industry/

http://www.bloomberg.com/news/2014-04-14/coal-rises-vampire-like-as-german-utilities-seek-survival.html

"Still, RWE has no plans to back away from lignite. The company is pressing ahead with plans to build a 1,100-megawatt plant at Niederaussem, near Germany’s border with Belgium. Planned to start operation in 2018, if it gets the final go-ahead it will cost cash-strapped RWE 1.5 billion euros ($2.1 billion) to build."

I missed this earlier...
> I don't have any issues with conventional plant really, we need them. But pretending that they
> are somehow so superior when they are off half the time (i.e. we need twice as many as it might
> seem) whether it is because of faults or maintenance or over supply is very odd behavior,
> wouldn't you say?

If you had thought about it, at all, you'd realise this is part of providing a high reliability resource.

Onewhere you can plan how much you are going to generate and when.

Unlike renewables.

Nial.

Nial, Raff is mistaking the effect that renewables and normal fluctuating demand have had on conventional stations for the actual time they need to be out of operation. Repairs and maintenance are a relatively small but growing part of the problem. There is the issue that many of the coal stations are now quite elderly and at least 10 years beyond their use by date but most of the main elements of the station will have been replaced over the years. The constant ramping up and down ages the plant quicker than continuous operation.

Solar energy has top priority because it can't be isolated or controlled in any way. Wind also has a priority and suppliers are keen to supply it because they get most money for it but sometimes the other supplies can't be ramped down fast enough and the wind companies are generously paid to stop supplying the grid. Since power stations became competitive (during end of the CEGB) most power stations wanted to supply as often as possible to increase their profitability but somebody always needs to be in reserve or off line to ensure supply so that means they can demand payment for being sidelined.

We are now seeing three things coming together to create havoc. Firstly, there’s renewables, 'nuff said. Secondly, a great many stations, including nuclear, are coming to the end of their life. Some of the coal plants have even been deliberately run till they break on the grounds they were due to be scrapped anyway because of sulphur dioxide and nitrous oxide emissions rules but now it turns out we need them. They haven't replaced the old stations because they weren't given any promises that they would get a decent return on their 40 year investment. Would you build a coal fired power station if an Obama like was going to emerge in the UK or the EU and wage war on coal? The third issue is the feeling that the grid was over supplied anyway. Seems like a good idea not to have too much expensive kit sitting idle. Let's be lean and mean. However, this isn't a product we can do without for a few weeks if we run short.

The solution they've come up with is a plan to get high energy users (assuming they haven't already left the country) to turn off and places with diesel generators to start supplying the grid. Gee, that will be cheap and CO2 efficient… NOT. They talk glibly about hotels turning off their air conditioning on winter afternoons to reduce the peak demand. WTF? Of course in those circumstances the shortage would be due to gas and wind which would mean the problem wouldn't just be about peak times. If they've done their sums correctly then the few times we come close to the edge, the backup plan will stave off power cuts. IF. If they've got them wrong, then people will suffer and trade will too. Ministers will get their heads to play with. Unfortunately, because everyone is playing brinkmanship, the new stations are not being built. The estimated completion date slides further into the future and the longer we balance on the edge.

To stave off catastrophe the government is also asking generators to mothball plant, not dispose of it. This seems simple in theory but it’s not. You can’t just turn the lights off on a power station and expect it to work 12 months later. You have to dismantle large parts of it (eg ball bearings become flattened if the weight of the turbine sits still and the shaft itself is not designed to be stationary for very long). Your employees won’t take zero hours contracts in the off chance they’ll be needed sometime. Parts of the station will still need to be continuously manned and the security may even need to be increased to prevent thefts of metal and equipment or vandalism. You also tie up the land which means you can't use it for a new power station or the ever popular business park. Land is money.

If renewables weren't part of the equation (but nuclear and hydro was) then the system would be much more predictable, allowing a better gauge of how much capacity we need. Everyone would be running more efficiently. Coal and gas would become more reliable investments. Renewables cost far more than the headline rate.

Nial, TinyCO2
I think I probably gave Raff an opportunity to hide behind smokescreens (possibly fro lignite) but when considering future profitability you have to consider the current situation. As has been pointed out to Raff the impact of renewables and the governmental/EU dictates on the market ensures that other plant goes into stanby. Unfortunately Raff uses the raw data to mean what he wants it to mean in his defence of Solar PV.

He has retreated somewhat from his original positions. However I think that like Chandra we'll never convince him that Solar doesn't produce any power from mid-afternoon until mid-morning the next day. Nor will he ever admit that there is a high demand after solar has shut down for the day and again before it starts up again in the morning.

SandyS "we'll never convince him"

Well, no but I don't like too much stuff flapping around unanswered. Makes it look like there isn't an answer.

TinyCO2
Agree, and there are plenty of answers.

Sandy (Jul 10, 11:38), yes and it planned many of them back in 2006-8. Solar will never be profitable - I don't think you have proven that. For a tech that has reduced in price so rapidly, such preductions are likely to be wrong soon. I'm not interested in wind because I can't put it on my roof, not because I dislike it on principle. There's a lot of power in wind so I don't see why it can't be used. For areas etc, see upthread - all of the US can be supplied by 100km^2 of panels in a desert. That is doable. Europe needs a desert, but maybe much of Spain will go that way... Your a,b,c,d are not unreasonable. We use the power ourselves anyway. But as a quid pro quo I'd expect you to pay for the safe disposal of all of the gasses you emit from your coal and gas plants, not dumping them in my lungs, and all the radioactive elements produced by your nuclear plant. And while we are at it you can pay for remediation of all of the pollution caused by production, transport and disposal of all fossil fuels and all of the goods in your use that came from China. And you can pay war reparations to the families of 200000 dead in Iraq (let's say 1 million a piece). And so on. That is a fruitless argument which you lose many times over.

Nial, hard to conclude they are "turning their back" on renewables and burning more coal. Q1 of 2014 from figures show coal/gas generation down significantly, renewables up (due to a warm winter, lots of wind). Exports are up, which confuses things. And as coal production is (or was, 2010) subsidised at 3bn Euro annually they will want to keep a market for that coal ;-) BTW is that a subsidy you and your friends object to so strenuously too? It has probably been going on for decades.

Tiny, those low capacity factors quoted by Sandy go back to 2007 so they are clearly not solar influence. Coal stations are offline half the time - there are twice as many as necessary in order to guarantee supply. Sorry. Coal and gas as more reliable investments without renewables? Well they have bee reliable cash cows for decades if that is what you mean. The good dividends they pay are a result often of monopoly or uncompetitive markets. Or their prices are agreed with a regulator on a sort of, you make electricity and well let you earn X% annually on top. Electricity supply is not a normal market.

Sandy, renewables making other plant go into standby? Well guess what, plant does that throughout the day anyway, renewables or not. Me not believing that solar does not produce from mid afternoon and there being continued demand at night? Well guess what, you can see curves of power produced and consumed on the Internet. It is no secret. Germany, which interests you so much, has a huge bulge during sunny days and(shock) none at night. Noone denies that. But guess what, demand goes up during the day and down at night. Even more shocking - solar is predictable.

"Coal stations are offline half the time" and that situation probably goes back even further because gas has been favoured since the dash for gas in the 90s and then coal was demonised by CO2 catastrophists in the 00s. For those reasons, new coal stations have not been built in the UK. The resurgence of coal is purely a financial decision based on the cheapness of coal and the realisation that old coal stations that did not comply with new EU rules on SOX and NOX would have to close anyway. Just because a power station isn't being called upon, doesn't mean it's not able to run.

It seems you only read the bits of other people's replies that you want to....

> Europe needs a desert, but maybe much of Spain will go that way...

As before, the EROI of solar panels in Spain is only 2.4:1.

Modern society needs an EROI of 10:1 or greater to properly function.

As I've said before, there are probably areas of the world where solar PV makes sense (remote African areas off grid/ Tenerife where the base load is generated with imported oil), but installing PV in Northern Europe is simply a _waste_ of energy.

You still haven't outlined the subsidies your installation gets.

Panels installed in the north of Europe may never generate the amount of energy required to install service and maintain them.

Raff
Anything which can only supply about 10% of demand for 1/5th of the time required is going to struggle to be profitable. Put some solar panels on your roof and run your life with them is the ultimate test of what you say.

Like all of us you pay for the extraction of what the government considers harmful from gas, coal and nuclear in your taxes and the price you pay. In a democracy that's how it works. When you buy Chinese built anything then there is no contribution to the clean up. Whereas most post industrial clean up in the UK and EU is paid for either by your taxes or the price you pay for goods and services.

Adding more expensive renewables to the mix, especially renewables which produce power at low or lower demand and forcing power companies to take that power will inevitably increase the amount of time perfectly good traditional power stations have to go on standby, thereby increasing costs and decreasing efficiency. That is 1st year mathematics. Solar peaks after demand has sharply risen during day and ends whilst demand is still high, wind is variable and just as likely to produce maximum output at 2am as any other time. Tides have a 12:20 cycle predictable but not helpful. Pumped storage only saves the cost of energy it still requires building a second power station so why bother with two lots of capital investment and two lots of maintenance, the reliability of electro-mechanical equipment left switched off and only used occasionally is reduced particularly at switch on when compared with that which is regularly used

I assume that you want to kill all, or virtually all as I think there are a few species which are exceptions, carbon based lifeforms; humans are carbon based lifeforms by the way, by removing all CO2 from the atmosphere. You practice what you preach by walking everywhere?

But guess what, demand goes up during the day and down at night

Nonsense
See:- This page here http://www.mpoweruk.com/electricity_demand.htm
and here
http://www.eia.gov/todayinenergy/detail.cfm?id=830
unfortunately American data but you can download UK data from here:- http://data.gov.uk/dataset/energy_consumption_in_the_uk and http://www.gridwatch.templar.co.uk/ to confirm the similarity.

Solar output charts for California can be found here http://robertrapier.wordpress.com/2007/07/28/a-california-solar-dilemma-3/ notice the sharp rise and fall in output and how output has dropped by 16:00 whilst demand will continue at least 80% of peak until 4-5 hours later.

You can check out how well you'd do here http://www.windandsun.co.uk/information/solar-power/calculating-pv.aspx#.U8EPPfmSySo

Even more shocking - solar is predictable.

*That is the biggest error I've ever read not even Chandra came up with that. Not even Richard Betts wouldn't claim his models are that good!

Apparently output can be reduced by 75% on cloudy days http://www.greenenergynet.com/businesses/articles/impact-clouds-your-solar-pv-system again even Richard Betts' super computer can't predict cloud cover two days in advance, sometimes not two hours.

I'm not going to discuss war reparations as this isn't the forum and that is an attempt to divert the thread.

*If you continue to think that after doing some serious research then I think that there is no convincing you of reality until you meet it face to face.

Nial, you state that with great confidence (EROI > 10:1) and I have seen it claimed elsewhere, but it is only an idea, not a generally accepted principle. Oil shale and tar sands have a poor EROI but I have read no complaint about it except from environmentalists. And the figure for solar in Spain you quote is just one of many for solar. As for northern Europe's solar, you might be right, although it sounds like just an opinion - or can you support it with a calculation?

Sandy do you think the developers in he links from the OP are developing loss-leaders or something. For what?

Democracy has no connection with with paying for pollution through tax. What a strange idea, where did it come from? Unless in your country the ballot papers allow you to select candidates and allow you also to choose whether you want to pay the costs of private companies. Who is going to say yes to that? It is like suggesting that voters paying to bail out bank shareholder and bondholders is all part of democracy. Are/were you a banker by any chance? I've heard they think that way.

A lot of what goes up chimneys is not paid for. But many people seem unconcerned - even people who wouldn't have a CFL bulb in their house because of the mercury it contains are unconcerned by the mercury in coal exhaust. Odd. Angry about chinese pollution - I once tried to avoid buying chinese products, ever tried it? I found it impossible. Do you really have no chinese products in your house?

Timing of solar power - like I have said, my panels give me power during the day when I need it. You can draw as many graphs as you like and that fact will not change.

Solar is not predictable? Where I live, the sun rises in the morning and sets in the evening. It is not always sunny, but much more often than not.

Raff,
One quick comment before I go to bed, he sun may well come up everyday but what days is output going to be cut by up to 70% by cloud cover and for how long? Can you say 24 hours in advance, the power generators need to know so they can keep you going those days. So you don't go out to work between the hours of 10:00 and 15:00 when solar is at maximum output of somewhere between 30% and less than 100% depending on a number of variables, a lot of people aren't that fortunate.

I'll check out the rest for factual accuracy later, your track record isn't that good at the moment.

Raff
Check the Mercury Cycle and never forget that everyone giving you "facts" has an an agenda - I do, you do your main sources of information Greenpeace and the Gaurdian certainly have more extreme agendas than you or I.
Hg Cycle summarised as
50/50 Natural/Human natural mainly volcanoes
From the above source human is broken down into
65% from stationary combustion, of which coal-fired power plants are the largest aggregate source (40% of U.S. mercury emissions in 1999). This includes power plants fueled with gas where the mercury has not been removed. Emissions from coal combustion are between one and two orders of magnitude higher than emissions from oil combustion, depending on the country.[4]
11% from gold production. The three largest point sources for mercury emissions in the U.S. are the three largest gold mines. Hydrogeochemical release of mercury from gold-mine tailings has been accounted as a significant source of atmospheric mercury in eastern Canada.[7]
6.8% from non-ferrous metal production, typically smelters.
6.4% from cement production.
3.0% from waste disposal, including municipal and hazardous waste, crematoria, and sewage sludge incineration.
3.0% from caustic soda production.
1.4% from pig iron and steel production.
1.1% from mercury production, mainly for batteries.
2.0% from other sources.

So in the USA 40% of 50% = 20% of all Mercury emissions are from coal not good but not the 100% you imply either deliberatly or accidently by repeating what you've been told or read without checking.

Democracy has a major connection with paying for pollution, in a democracy you can join any political party you want or even form one, you can write to and meet your MP to persuade them over to your point of view, you can demonstrate against things you don't like (Frack Off and Plane Stupid would be your groups of choice I'm guessing) you can go to planning meetings as a group or individual and speak against a development. In China doing any of these things will land you in serious trouble some possibly involving the death sentence. This situation allows the citizens in a democracy to protest with non-violent direct action and Chinese state sponsored industry to to pollute when ,where and who ever they like.

Of course I have Chinese products in my house, I didn't say I didn't. But I accept that this is an issue for me as a consumer. I don't want to drive more industry into the hands of a major polluter (I don't count CO2 as pollution) by making the costs of energy in general and electricity in particular uneconomic when taken on top of all the additional costs industry in the EU has. H&S, pollution controls minimum wages, maximum hours, transport taxes, driving restrictions, airport eco-taxes, after life disposal the list is a long long one. As I've said before the Germans have got the message than a nation that doesn't make and sell stuff is consigning its citizens to poverty.

I'm still in a state of shock that you think Solar PV works at 100% on cloudy days.

Before I go out for most of the rest of the day I'd like to summarise how far we've got. Do we agree

• You are not interested in wind but only viable domestic sources
• wind is not an energy source for domestic and small applications
• Wind is an intermittent and unpredictable source of energy for a national supply
• Solar PV only works for 5 hours around the solar meridian on cloudless days
• Solar PV output drops off rapidly outside the 5 hour peak
• Most domestic users in the UK are out at work or education during those 5 hours
• Cloud cover reduces PV output by up to 70%
• Cloud cannot be predicted and therefore grid planning has to be reactive which is inefficient
• For pollution living in a democracy is far better that living under a single party authoritarian regime
• In the USA about 20% of the Hg in the cycle comes from coal fired power generation (total US output around 110 metric tons that year)
• Seeming you mentioned them CFLs contain about 5mg of Hg
• Germany has change from renewable and nuclear to brown coal for economic reasons with some political opportunism thrown in
• The government forced use of solar causes traditional generation into standby raises costs directly and reducing reliability and further adding to costs
• All renewables must have some form of backup doubling the installed capacity for no good reason
• Renewables can have a place for remote communities and users but there is a vulnerability which must be taken into account.
• Feed in tariffs for renewables are unsustainable.

Sandy, you are very strange. I get the feeling that either you are bored and argue for the sake of argument or you are paid to argue against solar. I can't see why you would be so dogmatic otherwise. I made no claim that coal was responsible for 100% of mercury emissions - that is your own misunderstanding. Your list of mercury emissions proves my point: A lot of what goes up chimneys is not paid for. It hardly makes mercury emissions from coal acceptable just because it is not unique. Noone with knowledge and a choice would live near to such facilities and the emissions should not be allowed.

Your discussion of democracy and pollution is facile. *Cutting out* pollution takes place best under democratic societies, mostly under pressure from green groups such as Greenpeace and FOE. But paying for someone else's pollution has nothing to do with democracy. And as I said before, a lot of what goes up chimneys is not paid for by the polluter. Pollution from non-coal sources obviously concerns you greatly. If you want to push for cuts to pollution, joing FOE or Greenpeace. If you want to cut pollution caused by offshoring production to China, oppose globalisation or support the imposition of green import taxes. And most particularly, don't buy Chinese products.

And no of course it doesn't give 100% on cloudy days. I said nothing of the sort. I also think I said my PV is on my factory roof.

From your Gish gallop, wind is intermittent, but not entirely unpredictable. Conventional plant is also intermittent in a sense - that is why there are twice as many coal plant as are neccessary (<50% use). Your 5 hour figure is odd. It will depend upon the season and the latitude, after all, the Arctic gets greater insolation than the equator during summer. Clouds can often be predicted well. Germany hasn't 'changed' to coal. Look at https://www.energy-charts.de/power.htm and compare weeks in 2011 to 2014 and see if you can see a consistent pattern. Seems to me that gas has gone down, not renewables. Conventional plant needs plenty of backup too. That is why grids are engineered to allow for a GW or more of conventional to drop offline in an instant and not fail - because conventional is intermittent. Hence there are twice as many coal plant as are theoretically neccessary (<50% use). Renewables have a place everywhere. FIT are intended to be transitional.

Raff,
OK, I’ll keep it simple*. I don’t think I’ll be able to convince you that I’m even nearly right. The reasons I dislike Solar, Wind and Tidal (the intermittents) so much are as follows
1. I hate unnecessarily paying for the same thing twice or three times, all three intermittent sources require more backup than traditional; including traditional and STOR and involve paying for more than twice.
2. Like you I see no reason to create more pollution than necessary, duplication of investment does just that.
3. Having more capacity than necessary with a politically favoured supply leads to a situation where market forces close unused surplus. Because the market has been modified by political considerations to favour intermittent sources then there is a risk of rolling blackouts and brownouts these have the biggest impact on the vulnerable but leave none immune.
4. For Solar PV 5 hours is best case, summer subtropical cloudless day.
5. A stable grid requires reliable power sources the intermittents are not reliable and two are unpredictable, certainly not to the degree required.
6. FITs once paid are never recoverable, even if they are temporary measure as you suggest and which I very much doubt. Fits as set up in the UK move money from the poor to the rich.
7. Industrial Solar PV takes agricultural land out of production and moves it elsewhere, perhaps to places we’d rather were left as they are.
8. Hydro is my exception because it is much more predictable and has a rapid response time throughout the day.
* You might like to think about that arctic solar thing again, and consider what PV output you’d actually get from the sun at 60’N/60’S over 12 month. I’ll concede that the winter output will be more predictable.

With your chart for 2011/27 and 2014/27 Wind has dropped to 60% of 2011 confirming the problem with that, despite the time since Fr Merkel announced the close down of Nuclear it is still at 90% of 2011. In the current week solar varies by about 50% peak delivery day to day confirming that problem. Brown coal is relatively stable between the two years. My point about the short peak output for solar and the delay between the fall in solar output and the fall in demand is clear on many days, in 2014 there is a double peak in hard coal output which the Germans appear to use as a balance to a greater degree than pumped storage and hydro.

I still find it hard to understand why you think that conventional is intermittent when the only sources which go to zero or very low levels versus capacity are the renewables. Compare weeks 3 & 27 for both 2011 and 2014 and you'll see why even the Germans need to keep traditional ready to backup for renewables. I can't think of another industry where a contract to meet peak demand plus a safety factor 24/7 would include something that is unpredictable day on day and may fail due to something in addition to equipment problems.

Sandy, I'm having trouble keeping up with you. You are a prolific writer.

The market for electricity and energy is not a normal market in many countries. It is often a monopoly or if not, eg when it has been privatised, it was once. Assets are or were often built either with state backing (nationalised generators) or with financial guarantees or with guaranteed profits. Coal mining was often highly state backed (as I noted, 3bn annually in Germany still in 2010). Into this we are now throwing renewables with other distrotions and guaranteed markets or profits. It is not ideal, but that is what we have. It is fruitless to argue about who's subsidy is or was bigger. It would be nice to throw out all subsidies - I firmly believe that should be done, in particular those that encourage some truly disasterous activity in the biofuels sector. I am also sure that will not happen for a long time.

I also believe that solar will become a major part of most electrical systems. Subsidies created it and it is on its way to being mainstream without subsidy in sunny places - see the links at the top of the thread. Whether it will be so important in northern climes I don't know, but if I have to guess, I'd say yes as prices fall and efficiency rises. Utilities can try their best to hold it back but it is geting so cheap they will not be able to. I'm also fairly sure that electcric cars are going to soak up most of the peaks we see at midday and that the problem of there being too much at noon will disappear - in other words demand will rise and utilities might still be saved (in a different form).

The idea of Arctic insolatoin being high in summer is not fiction. See the curves at http://tamino.wordpress.com/2012/10/01/sea-ice-insolation/

The wind component in the Fraunhofer graph is not down as far as I can see. It is the gas that is down greatly (orange band). As you say, coal is being used for balancing rather than hydro. Why is conventional intermittent? Well it isn't the sense that the word is normally used, I'll grant you, but when a conventional or nuclear plant trips, it trips to zero in a flash, so when you say "the only sources which go to zero or very low levels versus capacity are the renewables" you are clearly wrong. Grids have been engineered to survive such events and spare capacity is kept for that reason. You don't consider plant intermittent because the grid has been engineered to make it look that way.

Raff,
I see you are carrying on two or more discussions, never easy, but replying at length in all so I don't think I'm in your league. Perhaps I didn't write clearly but the further you go towards the poles the less solar you'll get in winter when you need it most.

I randomly compared Friday 08/07/2011 with Friday 04/07/2014 (UK format) because the 2011 seemed to be maximum for the week, at peak 2011 wind is 5.09 (GW) and 2014 its 2.92. I don't doubt for one minute there is greater installed capacity in 2014 than 2011 what is causing the difference is the amount and strength of wind, by Saturday 05/07/2014 wind has gone up to 7.17 on a low demand day. But solar has fallen from 22.58 to 14.51. Which makes my point on day to day unpredictability.

I don't know enough about the German coal industry give you facts and figures, but from what I've read the situation is that deep mining subsidises are being phased out (by 2018?), lignite mining is open cast and not subsidised. The new fleet of power stations use lignite and are therefore not subsidised. They also are to EU standards. Perhaps explains the use of hard coal to balance the solar peak issue.

Just running the slider over the curve gives about 6 hours where the output of solar is 80+% of that days peak. for 2014/27 the daily peak varies between 14 and 23 and 2014/03 it varies between 3 and 6.

The output for 2014/27 is nearly 10% higher than 2011/27 but the scales are different which makes visual comparison impossible, but by using the slider you can see actual values and hard coal is up, brown coal is down slightly, nuclear is down slightly but the total for all three is virtually the same 2011 to 2014. What is also clear is that a lot more power is exported in 2014 than in 2011 on a daily basis. 10+GW quite frequently even in winter. Not sure of the significance of this, but exports begin at roundabout the same time as solar peaks, the importers appear to be Netherlands, Switzerland, Czech Rupblic and Austria. Austria doesn't appear to do well out of the imports:
http://www.reuters.com/article/2014/02/12/us-austria-energy-germany-idUSBREA1B0ZL20140212

Personally I think Solar will continue to receive subsidies for some time yet and will still continue to supply power to grids.

Australia's renewable energy industry grinds to a halt

http://www.smh.com.au/environment/climate-change/australias-renewable-energy-industry-grinds-to-a-halt-20140716-ztio2.html

If solar is so lucrative and the panels so cheap, why do they need a subsidy?

Johanna

A friend of mine runs three chicken sheds. His solar PV output drives ventilation fans, directly replacing mains electricity. He has had the system three years and expects to reach payback in four years time.

If you can use all you generate, solar PV is definitely viable,even in cloudy Northern Ireland.

Jul 16, 2014 at 6:41 PM | Unregistered CommenterEntropic man

And how would it do without the massive subsidy?

The PV units are generating for three chicken sheds and a house with no power going back to the grid. He is getting about £7000/ year in NIROC and saving £8000 on his electricity bill. Allowing £2000/ year for maintainance he's paying back the £90,000 capital cost at 13,000/year over seven years. Without the subsidy repayment time would be15 years.

That assumes constant electricity prices. The last increase was 18% in 2013. That increased his saving by £ 720, and brought his break even point forward by 9 months.

Entropic man
Are the chicken sheds heated in winter, if so my what means? Would he be better using energy from chicken manure as a cost saving, perhaps without subsidy?

http://www.fwi.co.uk/articles/01/02/2014/127615/turning-chicken-litter-into-renewable-energy.htm