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Who Subsidised Your Solar Panels, Mr Booth?

August 15, 2019

By Paul Homewood


The Telegraph published this letter today:




Unfortunately his “relief for the National Grid” argument does not stand up to scrutiny. Unless he plans to cut his electricity supply off completely, the National Grid will still need to provide enough dispatchable capacity to cover demand from him and all other solar powered homes, for the times when it is needed (during cold dark winters?)


But what about the economics?

The Eco Experts website has come up with a guide to costs:

1) A typical 3.8KW installation would cost £6000, plus £4250 for a battery.

2) It will produce about 3000 KWh a year, about 70% of total requirement.

3) The inverter would need replacing after about 10 years, at a cost of £1000

4) Annual cleaning costs of £100.


So we are looking at an initial cost of £10250. After about 10 years a new inverter would be needed, and certainly a new battery as well.

Current prices of electricity are about 14p/KWh, so savings of 3000 KWh would be £420 a year at current prices. Knock off the cost of cleaning, and you are down to £320.

Over a 20-year period, say, savings at current prices would be £6400, but the capital cost would be £15500 (including replacement battery and inverter).

On the face of it, a non starter.



Incredibly though, Eco Experts reckon the system would actually be showing a cumulative profit after 16 years:



So what explains the discrepancy?

This is the basis of their calculations:



It is not unreasonable to assume that electricity prices will rise over time, and I would not argue with a figure of 3.73%.

But what is missing from their calculation?

The cost of interest!

If you borrow £10250 at an interest rate of 5%, annual interest will be £512, more than offsetting the savings on the electricity bill.

Even with electricity prices rising each year, the cumulative interest costs still exceed cumulative net savings by Year 20.



In other words, there will no savings to use to pay back the capital outlay.

There is one other trick used by Eco Experts. They have assumed a current electricity retail price of 18p/KWh (though they don’t actually show this figure anywhere).

This may be in line with standard variable tariffs, but is well above widely available competitive prices around the 14p/KWh mark, which can be easily found on price comparison websites.

Many people, of course, cannot be bothered shopping around to save money. But it is unlikely that these folks will bother to install solar panels either to save money!


In short, our correspondent, Mr Booth, has been sold a pig in a poke. Unless he has the odd ten grand stashed away in a biscuit tin under his bed, he will never show a return on his investment, but lose a fortune instead. (There is a proviso here- generous government subsidies ceased in March 2019, so he may be in receipt of these, which will help to cover his outlay).

Certainly though, anybody who is tempted to follow his example had better do their homework, and not be taken in by the solar industry sharks!

  1. Bertie permalink
    August 15, 2019 8:19 pm

    I am looking forward to reading your response in tomorrow’s Telegraph. If they print it of course!

  2. JimW permalink
    August 15, 2019 8:23 pm

    Unless my braincells are dying; point 4 of ecoexperts has 100-79=11, now its a long time since my Maths A level and Physics degree, but is that how these sums work these days?

    • John Palmer permalink
      August 15, 2019 8:56 pm

      Nah… they were using a solar-powered calculator on a cloudy day!

    • JWJ permalink
      August 15, 2019 8:58 pm

      I saw that too. Wouldn’t the solar owner need to buy 21% (not 11%) of their electricity from the grid?

      And of course, that means the entire system has to have capacity for all of the solar users when they need that electricity.
      Unless the solar owners are willing to have their electricity shut off.

    • August 15, 2019 9:20 pm

      Perhaps they asked Diane Abbott to do the sums.

    • Pancho Plail permalink
      August 15, 2019 11:08 pm

      It does make you a bit suspicious of the rest of the calculations when they can be so cavalier with 10% of the cost.

      • Frank Everest permalink
        August 16, 2019 9:14 am

        Quote: “It will produce about 3000 KWh a year”
        I’ve got a 3.25kW array, almost ideally situated on my south-facing roof. The suppliers predicted that I’d get about 1,800kWh a year. After 4 years, I’ve been getting within 100kWh of that figure a year – and nowhere near 3000kWh. That error makes the calculations even more dire!
        As an amusing aside, I use almost exactly that amount of electricity in my electric car every year, so it’s nice to be able to drive and get paid my feed-in tariff at other people’s expense. Tut, tut!

  3. GeoffB permalink
    August 15, 2019 8:50 pm

    Before I retired from industry when we invested capital into a new project the accountants had various formulae to calculate payback period. Internal Rate of Return (IRR) and Net Present Value (NPV) were just two of them both fairly complex for us engineers.
    So we had are own set of simple rules, if it paid back in a year do it….if it paid back in 2 years do it, but only if you had no one year paybacks..if it paid back in 3 years forget it. 16 years payback from eco experts is ridiculous. Mr Booth sure has been stitched up, the sad thing is he thinks he got a good deal.

  4. MrGrimNasty permalink
    August 15, 2019 8:51 pm

    I wonder what the end-of-life disposal costs for the panels and batteries will be, toxic waste is not cheap to get rid of.

    Then there is the issue of how long does it take to recoup the energy used to make all the equipment – it’s borderline if this system will actually create more energy than it used to make?

    • Ian Magness permalink
      August 15, 2019 9:15 pm

      There was a beauty of a plea in my local social media website last week on this subject. Somehow or other, this man’s roof needed repairing. The problem? It was covered in solar panels and he wanted someone with experience of repairing such a roof without having to remove and re-install the solar panels. Doh!
      This highlights just one of so many issues with these things that the solar companies won’t tell you as they push back the payback periods, possibly indefinitely.
      Other issues include snow cover, or even heavy rain reducing productivity. Readers of this site will, no doubt, know many more.

    • Paul Petley permalink
      August 15, 2019 9:21 pm

      Euan Mearns did an article on that following peer reviewed research on PV systems energy returns in high latitudes. If you haven’t already come across it here it is.

    • Paul Petley permalink
      August 15, 2019 10:25 pm

      There are some interesting figures on that in this Euan Mearns article.

  5. HotScot permalink
    August 15, 2019 8:51 pm

    Might Mr Booth be a retired gammon with a few bob in the bank and the spare time to devote to all matters ecological?

    Nothing worse than seeing loads of old geezers and gals who have plundered the planet to feather their own nest, now living off pensions heavily invested in fossil fuels, coming out as ‘geriatric greenies’.

    If there has been damage done folks, you effing well did it. Don’t get all righteous now and seek to cleanse your soul before pleading your case at the pearly gates. Have some dignity. If there is a god, i’m certain he’d rather you told the truth than seek to absolve yourself in the run up judgement day.

    • Roger Cole permalink
      August 15, 2019 10:56 pm

      If there is a reasoned argument to be made here it is not done with smears, pointless insults and class snobbery hate speech. You devalue yourself with this cheap stuff.

      • August 16, 2019 10:47 am

        Roger I’d agree with you if he was genuinely being hatey and using “hate speech”
        but HotScot uses “gammon”, “old geezers”, ‘geriatric greenies’ with his tongue in his cheek and I get his point

      • HotScot permalink
        August 16, 2019 3:11 pm


        Hypocrisy is always is a reasoned argument.


        Much obliged, and you are 100% correct.

  6. Martin Thomson permalink
    August 15, 2019 8:53 pm

    Biggest flaw in these calculations is the following:
    Most of the electricity produced by the panels will be in the middle of the day in summer, when most UK households do not use much electricity, so a large proportion of the production will go back into the grid (and receive some rebate as a result, but massively subsidised by the rest of us). So the assertion that the 3,000 Kwh produced will all be consumed by the household (79% figure) is complete cobblers, even taking into account the battery, which will only store a tiny amount of the summer surplus.
    Another example of fantasy renewable economics

  7. August 15, 2019 9:17 pm

    Thanks for this calculated example. I could not have done it. But what it shows is the basic scam solar energy is. Just imagine you got a loan offer from the bank and the bank, just somehow, left the interest out before you signed. In case you are stupid enough to sign up, you would have a whole armory of legal tools for redress. We should apply the same stick to renewable installers. If they cheat on the calculations they use in order to pull homeowners over for signing, they should be liable to pay the difference out of pocket. That would end those scams real fast.

  8. Pancho Plail permalink
    August 15, 2019 9:42 pm

    The calculations also ignore the fact that the efficiency of solar panels degrade over time. The figure according to one commercial supplier is a loss of between 0.5 and 1% per annum, and the guarantees on panels are for 80% efficiency after 25 years (and I tend to be sceptical of claims for performance over that length of time as no-one is going to measure and claim in reality).

    • Jud Kirk permalink
      August 15, 2019 11:50 pm

      I seem to remember being told that the drop to 80% happens in 8 to 10 years.

  9. Philip Foster permalink
    August 15, 2019 9:48 pm

    When called by these eco-sharks selling panels, if time permits, I ask them why they want me to steal money from my neighbour. I then, when receiving a puzzled reply, point out that the subsidies I get are paid for by raising everyone’s electricity bills.

  10. August 15, 2019 10:07 pm

    The electricity supplier pays a subsidy per kilowatt generated. The inflation-linked amount is just over 54p per KW at present, tax free.

    • Jud Kirk permalink
      August 15, 2019 11:53 pm

      Depends when the panels were installed as subsidies were cut a couple of times before being scrapped completely recently

  11. August 15, 2019 10:15 pm

    I guess you would have to want to stay in your house for the next 20 years. No buyer would want to pay extra for solar panels.

    • Sheri permalink
      August 16, 2019 12:11 am

      Especially aging ones.

    • Wendy permalink
      August 16, 2019 7:33 am

      I sold my house 3 years ago, the 1.5kw system on that house added value to the sale. It was just out of its 5 year warranty but was still generating quite well.

  12. Rowland P permalink
    August 15, 2019 10:27 pm

    Missing bit out of the calculations is the daily standing charge which bumps up the tariff.

    • August 16, 2019 9:56 am

      That’s right, but you’d still have to pay that charge even if you had solar panels (unless you cut yourself off from the grid!)

  13. Paul H permalink
    August 15, 2019 11:00 pm

    The guy over the road has two rows of seven panels. We’ve been here six and a half years and they were already installed when we arrived so I don’t know how long he’s had them. A couple of weeks ago a white van and a man and his lad turned up and changed three of the panels. Three down, eleven to go, 21%. Don’t know the bloke well enough to ask about it, plus don’t want to embarrass him. I may find out from another neighbour who knows him better, if so, I’ll update.

  14. Graeme No.3 permalink
    August 16, 2019 12:16 am

    We have this problem in South Australia with people rushing to put solar panels on their roof “to save money”. Then they add a battery so they will have power during blackouts.
    To add to the figures Inverters last about 7 years here, mine went after that. Even the most expensive one with the best reputation will only guarantee them for 7 years. Cost £1040.
    A 3.8kW set of panels are around £2,000-2,500 but most new purchasers spend around £3,000-3,500 for a 5kW set. Average generation is 17% of theoretical when new.
    Yes, the panels lose efficiency as they age, mine are down about 9-10% after 9 years.
    On top of that the State Govt. is offering a (one off) subsidy of £2750-3250 towards the cost of a battery (about £7,000 installed).

    My installation has been fairly successful. I have almost paid off the original capital outlay + inverter. I was able to use a neighbours figures for costing. Without any “subsidies” the return was 1.1% p.a. i.e. ludicrous. From their generation figures I expected a return of 6-8% but in practice, thanks to the government mandating a high feed-in tariff I get 16-19% p.a. and haven’t paid an electricity bill for 8 years. The mistake was that their panels were failing and they had to install a new set after 8 years. Another neighbour has also had to replace his set after an electrical fire which fortunately didn’t do any structural damage (apart from the panels and wiring).

    Those rushing out to spend £10,000 in order to qualify for a one-off subsidy of £2750 will be disappointed as the feed-in tariff is now one sixth of what it was when I purchased, although some Retailers will credit you with £88 per MWh (average household consumption would be 4.5-6.5 MWh p.a.).
    The advantage for the government is that the panels+battery extend the supply into the evening peak hour in summer which is the peak consumption time, but the cost of electricity is being pushed up as conventional generators are being squeezed out of supply. Eventually the State will have to depend on diesels.

  15. Wendy permalink
    August 16, 2019 7:27 am

    I’m laughing, ok, I do live in Australia, but I’m in Victoria, I have a solar system, no battery though as they are still expensive and to reap the rewards probably wouldn’t pay back in its current life span. But my solar is saving me plenty. I’m saving an easy $200 per quarter all year, plus I’m using reveres cycle aircon to heat so I’m also saving $300 every 2 months on Gas and during summer the aircon is free.. our supply charges are over $1.20 per day for power and $0.8 cents for gas, with the now $0.12 per kw put back to the grid my electricity bill is about $75 per month. My gas is about $65 per month. The cost to install this system was $4500 less the state government rebated $2225, so my cost will repay itself in less than 2 years. I’d actually say it’s nearly paid for itself in the first year. Our $ is equivalent to about 65pence.. the system I installed is about 6kw of panels and 5kw inverter, as we’re capped to 5 kw by our distributor.

    • August 16, 2019 11:20 am

      I have seen such optimistic solar claims before, which haven’t stacked up on close examination
      The SAVINGS claims here
      : Electricity $200 per quarter = $800 pa
      : Gas s $300 every 2 months = $1,800 pa
      The COSTS claims here
      : “gas is about $65 per month” =$780 pa
      (so saying the old gas spending was $2,580 pa, which seems an awful lot for Melbourne)

      “supply charges” : leccy over $1.20/day = $438pa : Gas $0.8 cents/day = $292 pa

      6kw of panels and 5kw inverter cost $4,500
      vs a total saving o $2,600pa ($1,800pa is a gas saving)
      It’s this claim that gas bills have dropped by 70% that seems incredible

      Now solar hot water panel scan be viable, but Wendy doesn’t mention them
      (I’d still go for instant gas, cos the infrastructure costs is so much lower)

    • A C Osborn permalink
      August 16, 2019 3:10 pm

      Wendy, nice to know that you are so happy having that tax payer’s $2225, I am sure that if you asked them personally to cough up their share they would tell you where to go in no uncertain terms.
      I suspect you think that as the State Government is paying you it would be stupid to turn it down, except of course it is not their cash you are getting.
      I am also sure that Graeme No.3 agrees with you.
      Would you have considered it such a good deal without their contribution?

    • Bertie permalink
      August 16, 2019 7:54 pm

      The poor mugs who don’t want to saddle themselves with all the long-term problems of fitting solar panels are paying your (and others of your ilk) ‘subsidy’ in increased tariffs on their regular bills. If only they realised!

  16. Chris Morris permalink
    August 16, 2019 7:40 am

    The big thing that the Grid provides, and which isn’t mentioned, is stability. Where does he get the 50Hz signal to produce the AC waveform? When he switches on a large motor, where does the inrush current come from.
    You can run the system independent of the grid but it needs to be a lot more sophisticated to use standard household appliances and cope with the load swings. Otherwise the life of the electrical components will be very short.

  17. Gerald Brady permalink
    August 16, 2019 8:09 am

    Anyone with £10,000 in the bank and getting less than inflation interest rates would look at this differently. I’ve had my panels for nearly nine years and never had them cleaned. The rain does that for me so according to you, the rain has saved me £900…. good old British weather.

  18. August 16, 2019 8:42 am

    The manufacturing costs of Solar Panels or Batteries is a fraction of the purchase price.
    Economy of scale can reduce prices more. Plus manufacture in low wage economy’s like China , India or North Korea.
    As for Interest on loans which is money that the banks (rich people) create out of thin air.
    Just shows how FUBAR society is.

    This rather interesting history of the Bank of England
    England’s crushing defeat by France, the dominant naval power, in naval engagements culminating in the 1690 Battle of Beachy Head, became the catalyst for England rebuilding itself as a global power. England had no choice but to build a powerful navy. No public funds were available, and the credit of William III’s government was so low in London that it was impossible for it to borrow the £1,200,000 (at 8% p.a.) that the government wanted.

    To induce subscription to the loan, the subscribers were to be incorporated by the name of the Governor and Company of the Bank of England. The Bank was given exclusive possession of the government’s balances, and was the only limited-liability corporation allowed to issue bank notes.[14] The lenders would give the government cash (bullion) and issue notes against the government bonds, which can be lent again. The £1.2m was raised in 12 days; half of this was used to rebuild the navy.

    This is how a few rich people were given the legal right to create money out of thin air and lend it out at interest.
    Britain remained on the gold standard until 1931, when the gold and foreign exchange reserves were transferred to the Treasury; however, they continued to be managed by the Bank.
    After that money created and issued at interest by these rich individuals became fiduciary (based on trust)

  19. robert jenkins permalink
    August 16, 2019 8:44 am

    I am not a great believer in Man Made Global Warming but I have had solar panels installed because the economics do work in my circumstances. The solar panels feed excess power direct to my immersion heater thus saving me a small fortune in LPG costs. Because LPG is so expensive the savings in LPG and electricity, together with the Feed In Tariff, amount to around £900pa, which on an investment of £6000 is not bad.

  20. SimonfromAshby permalink
    August 16, 2019 8:58 am

    I think that the important point is that the grid still needs to have the capacity to supply the householder with their full requirement for electricity for when the sun isn’t shining and the battery is flat. You can’t charge the battery when you are using the electricity.

    This means that their is no benefit to either the householder or the grid.

    The only beneficiaries are the panel selling eco-sharks.

  21. Mike Higton permalink
    August 16, 2019 9:04 am

    If there’s a power cut do these domestic systems keep producing? I think I have read that they shut down to avoid the risk of pushing volts back into the network that someone is trying to repair, unless they are fitted with some extra controls.
    Any experts here to comment?

    • Dave Ward permalink
      August 16, 2019 10:21 am

      It’s known as “Anti Islanding”

      If you want your system to keep powering the house when the mains fails, you’ll need additional switchgear to provide that separation between your inverter and the grid.

  22. Coeur de Lion permalink
    August 16, 2019 9:15 am

    Me “I’m thinking of installing solar panels- it’ll cost about £13,000 and we get this Feed In Tariff…..”
    Son “How much do you spend on electricity?”
    Me “Oh, about £500 a year”
    Son “Keep your. money for electricity , you’ll be dead in 26 years. You’ll be aware that the FIT used to be 43p per kWh and is now 3.9p?
    Me “Oh”

  23. Roger Duke permalink
    August 16, 2019 10:07 am

    A lot of your calculations are wrong. The cheapest rate I can get for electricity is 16.5 p per unit plus a fee of over 20p per day. I’ve had experience of solar in my previous property and my present one. You don’t need to spend £100 per yr on cleaning. Cleaning is as easy as clearing your gutters. My inverter in the last property is still working well after 10 yrs. You’re building a case against solar on a false information.

    • August 16, 2019 12:24 pm

      The £100 figure comes from Eco Expert.

      And I pay 14p/KWh for my electricity – I suggest you shop around! (The standing charge, BTW, is irrelevant as you would still need to pay it even if you have solar panels – unless you want to cut yourself off from the grid)

    • MrGrimNasty permalink
      August 16, 2019 12:52 pm

      Roger, you’ve picked on a couple of very small costs/discrepancies, and gone ergo the whole case against solar PV is false. Rather silly, and shows you yourself have an agenda.

      Any neutral look at the costs and energy used in manufacture will lead any sane person to conclude it is not and never will be economically viable or environmentally sustainable.

      Solar PV would never exist if the electricity generation market were not highly distorted by politics.

    • JUD KIRK permalink
      August 16, 2019 2:55 pm

      “Cleaning is as easy as clearing your gutters”
      Really, that is just plain silly! Panels are 1.6m by 1m approx so straight away you have to reach up at least 1.6m. to clean the top. If you have one above another life really is fun.

    • August 16, 2019 3:06 pm

      In the UK the argument for £100/pa cleaning is weak, cos of the frequesnt UK rain that will wash off pigeon crap.
      However as with anything there will be service costs
      like inspections to check the panels, inverter, to check they haven’t been damaged in a storm
      as well as costs of repinning them or replacing them after a storm
      as well as insurance costs.

      • August 16, 2019 3:07 pm

        You get things like pigeons making their nests under the panels , so then you have to out up anti-pigeon guards etc.

      • Bertie permalink
        August 16, 2019 8:01 pm

        BTW – Pigeon crap does not ‘wash away’ in rain I forget the chemical reason – is it something to do with calcium?

  24. europeanonion permalink
    August 16, 2019 10:37 am

    Paul Homewood extremely active on the Daily Telegraph today…he’s steaming!

  25. Harry Passfield permalink
    August 16, 2019 10:52 am

    You can maybe also add to the costs any increase in home insurance (fire-risks) that the panels and inverters (and batteries, perhaps) may cause.

    • Paul M permalink
      August 19, 2019 4:32 pm

      you might also find that any power conditioning circuits in the solar power system make it less likely that a power surge will destroy appliances in your house. some solar+battery systems will run the house, reducing the change of a power cut ruining the contents of fridge/freezer.
      so maybe it’s not all doom and gloom eh?

  26. Arthur Clapham permalink
    August 16, 2019 11:22 am

    Advice from a Stockbroker when I first traded in 1986, if a Stock looks to good to be true it usually is! And there nothing worse than the smell of burning flesh,especially if it’s your fingers! Advice which I have always adhered to. I think similar caution should apply to Solar Panels

  27. August 16, 2019 11:35 am

    As ever full life cycle costs have to be considered
    and it’s easy to miss some
    #1 the decommissioning costs of removing and disposing of old solar panels
    #2 the LOST taxes
    The guy who claims he has saved thousands on gas bills
    Actually that gas bill includes taxes and the gas will initially have had a mining tax on it.
    Say if $1,000 gas actually consists of $600 in taxes that pay for hospitals etc.
    well the gov has to increase our taxes by $600 elsewhere to keep funding those hospitals

  28. Graham lashmar permalink
    August 16, 2019 12:35 pm

    I have a 3kw system 5yrs old now. Cost 6k …Getting second faze payments for f.i.t. .this returns average 600 per year. The battery system was a step to far not adequate for the job. But hey ho. In short we were conned. Perhaps we should get a ppi deal . Like the banks ?? My system still working ok. So still earning. But I doubt I’ll get my out lay back. Industry assisted by this and previous governments. Like smart meters don’t work. It’s probably corrupt. As is the whole power industry probably??

  29. Gerry, England permalink
    August 16, 2019 1:55 pm

    Just to point out a couple of interesting articles around that might warrant further comment.

    In CityAM yesterday Nissan boss – that’s the new one who is not in gaol – saying that the UK has more EV charging points than petrol stations. So what is the comparison on fuel nozzles to plugs. There are 2 empty parking bays at the station vs 8 pumps at the Shell garage. How about throughput? And as far I know there has been zero public money spent on petrol stations – not quite the same with charge points Mr Nissan eh?

    Telegraph article saying the power failure culprit windfarm received £100k the next day to reduce output. If wind played no part in the shutdown, why was wind power kept to much lower levels the following days? Not telling us something National Grid?

    • Ivan permalink
      August 16, 2019 4:28 pm

      the main reason that wind is curtailed is simply a shortage of transmission/distribution capacity. It is mainly Scottish wind that suffers curtailment for that reason. But that has been reduced by the Western HVDC link (when it manages to operate). They generally avoid curtailing off-shore wind because financial terms mean it is more expensive to curtail. But it could be a simple transmission constraint, if on the Saturday the wind portfolio was unbalanced and there was too much coming in off the east coast they couldn’t integrate it all.

      But the circumstances do suggest a different potential reason that day. There is another reason for curtailing wind, and that is to ensure there is a sufficient amount of spinning reserve for system security. Because the day after the power cut was a Saturday, demand was lower. But it was similarly windy, so the amount of gas on the system, which provides spinning reserve, was rather low on the Saturday. It was down to 3.5-4GW much of the day.

      Spinning reserve is typically provided by gas generators running at less than full capacity, so that they can turn up (or more rarely down) quickly. Pumped storage and batteries can provide very short term reinforcement, but spinning reserve can provide a longer term reinforcement. To have spinning reserve, you can’t be spinning at say 1% of capacity, I think it has to be at least 30-50% or something. That’s why you have to materially curtail other sources of supply to be able to have it, and that usually means wind.

      This is mainly about changes at the 2 to 4 hour time horizon, and is mainly about the difficulty of getting a sufficiently accurate wind forecast at that horizon to know how much supply to need to deal with those changes. At 2 hours, we have a good enough forecast of wind, but at 4 hours we don’t. At the 2 hour range, you only have about a 60% chance of turning a gas generator on from cold, whereas it gets more like 95% at 4 hours. So the 2 to 4 hour window is where you can be caught unawares by a change in wind and not be able to get the gas on fast enough. And you will need something that can say on rather longer than a battery.

      • Chris Morris permalink
        August 17, 2019 3:26 am

        Ivan The main reason they want the gas units on is inertia, not spinning reserve. The problem with too much wind, as SA proved, is that when things go wrong, the frequency change is so fast that they can’t shed load fast enough for load shedding to work. That is why they have minimum inertia settings.
        The wind farm promoters talk about modifications to get synthetic inertia from the farms, but it isn’t. It is droop and they want to be paid an arm and a leg for it. With synchronous plant, you get it for free.

    • Paul M permalink
      August 19, 2019 4:30 pm

      “UK has more EV charging points than petrol stations”… you missed a word… “more PUBLIC ev charging points”. Most people charge their EVs at home, because they have electricity at home. Most journeys are well within the range of their EVs, so don’t need public charging most of the time.

  30. ThinkingScientist permalink
    August 16, 2019 3:01 pm

    Looking at the graph, I calculate that for household consumption of 3800 kWhr each year and a compound growth rate of 3.73% then to get cumulative electricity costs of over £30,000 by the year 2042 the unit price of electricity they start with today would be 24p per kWhr.

    Also, they haven’t allowed for inflation on the cost of invertor and battery replacement. There is also no loss of efficiency over time either. Even with all that in its favour the average cost of the electricity produced (assuming no subsidy) never gets below 30p per kWhr until near end of life at 22 – 24 years (by which time they are modelling grid electricity as costing about 54p per kWhr).

    They seem to be pricing on the basis of invertor replacement at year 10 (2029) and battery replacement at year 12 (2032 – and note they don’t show the next battery replacement, conveniently off the chart to the right!). With the same 3.73% compound growth rate applied to the cost of those replacements and assuming a straight line panel degradation to 80% efficiency at 25 years I calculate that the solar array can never produce electricity cheaper than you can buy it from the grid (without a subsidy of course). Ignoring cleaning costs but including inflation the cheapest cumulative rate gets down to 34p per kWhr just before you replace the battery at Year 12. (My cumulative rate is by dividing the total costs to that date by the total produced electricity)

    Ignoring inflation but including the cleaning costs, the lowest price for the solar array is about 29p per kWhr at 24 years.

    On a today’s money basis you would only (approximately) get the graph they show if electricity cost 27p per kWhr, giving you a benefit from year 16. However, in today’s money and with electricity at 21p or less per kWhr it would never pay to have the solar, based on their figures.

    I don’t think the figures in that chart add up at all and I think they are seriously misleading people. They only work by showing future electricity prices with assumed inflation and solar prices in today’s money and with no loss of efficiency.

    Anyone else care to check it?

    • Ivan permalink
      August 16, 2019 4:48 pm

      Rather than adding spurious accuracy to such a calculation, let’s look at what the market thinks. The market is often a good test of what is good value. Now the FIT has been closed and the new arrangements are much less generous, very little domestic solar is being retro-fitted to existing properties. It has pretty much completely dried up. People do not find it makes sense.

      If you want solar power, I think it is better value to locate it in Spain and build a transmission line to get it here. You get twice as much off your solar panel in southern Spain, and less seasonal variation. But the system doesn’t allow that.

      Interestingly, the solar PV market has dried up in Spain too. FITs ended in 2014, and growth of PV pretty much dried up at that point. Even in Spain, people won’t install solar PV without a FIT. And if it isn’t worth it in Spain, how can it be worth it further north? In any case in southern Europe, it is often more effective to use your roof-space for solar water heating. It is widespread in Greece.

    • Paul M permalink
      August 17, 2019 7:44 am

      The battery doesn’t just die at some notional age or cycle count. And, battery prices are FALLING, so why do you put “inflation” in the and sentence as “battery”.

      Inverter prices are likely to fall in real terms too. All electronic goods do.

      That said, labour costs will rise, but refurbishing old installations will be mainly just swapping units, fat cheaper than a new installation.

  31. swan101 permalink
    August 16, 2019 5:23 pm

    Reblogged this on ECO-ENERGY DATABASE.

  32. Paul M permalink
    August 17, 2019 7:16 am

    Some actual tell figures to offset your speculation

    My pv/battery system is 4.8kW with 6kWh storage, and cost £11,000

    The pv array is guaranteed for 25 years and still have 90% performance

    The battery is guaranteed for 6000 cycles, and still have 80% capacity. If I fully discharge and recharge every day, that’s a lot more than 10 years! And, the battery will still be useful, I won’t be chucking it away like you say.

    And that changes the story. Everybody keeps repeating the myth that the batteries or solar drop dead at a particular age or number of cycles. No, you simply lose performance.

    Perhaps you’ll amend your blog post with this in mind?

    • Jud Kirk permalink
      August 17, 2019 2:13 pm

      So your batteries will store a £1.00 worth of electricity!
      As most solar panels guarantees are for 80% after 10 years you may be rather disappointed. Probably not as disappointed as when you try to claim on your guarantee for the panels and batteries from the installer.. There again, unless it’s an inverter that stops working or the battery fails completely how would you know they are not working at the 90% level (for the short period they operate at peak output).

      • Paul M permalink
        August 19, 2019 4:26 pm

        obviously there will be some days the battery won’t get charged, the weather has to be really terrible for that. but yes, in theory the battery could store roughly £1/day, so lets say 330 a year, that’s £3300 over ten years. And the battery pack actually cost about that.

        how do I know whether the system is performing as specified? these units have things called computers in them which monitor performance and give me lovely graphs showing everything I need to know and more. I can see the peak voltage, current and power from the array, the battery charge and discharge rate, grid import/export etc.

        Sometimes I think people want to live in a world where we’re all choking to death from NOx produced by internal combustion vehicles, and it’s raining acid rain from having burned coal in our fire places at home?!!

      • August 19, 2019 5:20 pm

        Our air is cleaner than it has been for centuries.

      • Paul M permalink
        August 19, 2019 4:27 pm

        no, my panels are guaranteed to be 80% at 25 years.
        the battery is guaranteed to be at 80% at 6000 cycles, far more than ten years.

        am not sure if you’re trolling or not

  33. Paul M permalink
    August 17, 2019 7:39 am

    Note too that electricity prices have been rising faster than inflation, and that likely will continue.
    Meanwhile if you have cash savings, the interest rate will be 2% at best. You can easily borrow at 2%.
    A properly specified pv/battery system can also power your property (or part of it) in the event of grid failure, this can be a valuable feature to some.
    Then you can top up your battery at 1am when tariffs drop to 5p/kWh, should it be necessary, ready to reduce using normal priced electricity at breakfast time. People who have electric showers would appreciate that.

    • August 17, 2019 10:58 am

      Note too that electricity prices have been rising faster than inflation, and that likely will continue.

      That’s already factored in, with the assumption of 3.73%pa

      You need to remember that all of these costings come from Eco Expert, who are desperate to promote solar panels!

      And I certainly don’t know where you could borrow for 2%

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