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Silly Jilly’s “Battery Boom”

August 7, 2019

By Paul Homewood



Silly Jilly has not got any better since she joined the Guardian:


The UK risks being left behind in Europe’s home battery boom because of a controversial tax hike on solar-battery systems, according to a report.

The energy consultancy Wood Mackenzie has predicted that Europe’s home battery capacity could climb fivefold in the next five years as more households plug their rooftop solar panels into battery packs.

The analysts expect that by 2024, annual home battery installations across Europe could total more than 500MW, the equivalent of building a new gas-fired power plant every year.


The report said the battery boom had already taken hold in Germany and would accelerate across Italy and Spain as battery power became more economic.

However, the UK is likely to lag behind its European neighbours due to its “unfavourable” policy frameworks and a VAT increase for solar-battery packs this October.

The UK has blamed EU rules for the VAT change, a claim disputed by Molly Scott Cato, a Green MEP for South West England.

“There is appetite from [UK] utilities and technology providers but the market has no incentives so is lagging behind thus far,” said the report. “The recent VAT increase from 5% to 20% confirmed to begin in October 2019 is not an effective way to kickstart a market with challenging economics.”


The so-called tax hike simply brings VAT on solar-battery systems up the standard level charged on all goods.

If solar technology is so brilliant, surely paying a bit extra in VAT should make no difference at all?

Silly Jilly also claims that the projected increase in solar systems across Europe will be the equivalent of building a new gas-fired power plant every year. In fact, as the graph shows, it is the cumulative capacity by 2024 which will be equivalent to one power plant, and not one every year. (see update below)

As usual though, she also gets thoroughly confused between CAPACITY and OUTPUT. To compare 500 MW of solar panels with a 500 MW power station ignores the fact the the former will only produce at 10% of capacity, if you are lucky and extremely irregularly.

But what about the economics?

According to the Tesla website, a 5KW Powerwall battery will set you back £7750, plus installation of up to £2800, not to mention a host of other costs such as electricity upgrades. (You will apparently need two Powerwalls if you have EV charging equipment.



On top of that, of course, you will have to spend thousands more on installing solar panels, so you probably won’t get much change out of 20 grand.

Given that average household electricity bills are around £500 a year, the pay back period would be 40 years, even if you paid no interest on the outlay. At a rate of 5% interest, interest alone would amount to £1000 a year.

The batteries have a warranty of 10 years, but will likely start to deteriorate long before that. It is unlikely that the solar panels will last much longer either, and will certainly need maintenance.

In short, solar/battery systems are a non starter, even in sunny countries, unless heavily subsidised.

Looking at the graph, the current deployment of home battery systems is just over 200 MW. At 5 KW each, this would equate to 40,000 homes throughout Europe, a microscopic number given that Europe has an estimated 221 million households.

Silly Jilly seems to think doubling this number is a “boom”!


A report from Green Tech Media confirms that the above graph is annual additions to capacity, and not cumulative capacity.

  1. August 7, 2019 2:07 pm

    Reblogged this on Climate- Science.

  2. paul petley permalink
    August 7, 2019 2:22 pm

    Is it compulsory for journalists to not know the difference between units of power (watts) and units of energy (watt hours)?

    • Sheri permalink
      August 7, 2019 4:11 pm

      Seems so.

    • August 7, 2019 4:11 pm

      Yes. It is.

      The equation with gas power stations is utterly ludicrous – not just because of the difference between capacity added every year and total capacity – but because the batteries will only be operating intermittently, not 24/7 like a gas power station.

      So the quantity of batteries by 2024 will be equivalent to one gas-fired power station, albeit one that only operates for an hour or three in the evenings (but not in winter).

      • August 7, 2019 4:27 pm

        I humbly backtrack. The graph may, after all, indicate annually added power, not cumulative.

        Searching for other data on installed capacity in Europe to confirm or refute this, I discovered that there is an EU project called “BATSTORM” – battery storage to drive the energy transition. It says 600 MWh was installed in 2017. That would give the average capacity of the batteries in the Guardian’s graph as about 4kWh.

      • It doesn't add up... permalink
        August 7, 2019 5:28 pm

        Batteries produce no power at all. They simply redeliver about 80% of the energy that was produced elsewhere to charge them.

    • August 7, 2019 7:19 pm

      And politicians too, particularly energy ministers.

  3. Phoenix44 permalink
    August 7, 2019 2:52 pm

    What on Earth happens in 2023 and 2024 in that graph!?
    Let others subsidise stuff until it is properly developed. We lose nothing that way.

    • Sheri permalink
      August 7, 2019 4:12 pm

      The magical unicorn arrives and convinces people to buy more and more and more solar. Surely everyone knows that.

  4. John Palmer permalink
    August 7, 2019 3:01 pm

    At least she’s left the DT for her spiritual home, The Grauniad! The bad news for we DT readers is that there appears to be something of a ‘production line’ of Silly Jilly wannabes -all spouting the same mindless, un-researched piffle.
    Whatever happened to Journalism?

    • Paul Petley permalink
      August 7, 2019 3:09 pm

      I do wonder how it works at the Graun. Recently they have had three articles by separate authors all making the same mistake of discussing the future financing of the “new” Sizewell B nuclear power plant. Only one of the three articles was corrected to Sizewell C after I and others pointed the error in the comments section. You have to consider it is incredibly unlikely that three independent researchers would either all make the same typo or misinterpret separate sources of information. My only conclusion is that all three journos were given a “brief ” to work around and put out a smear article on nuclear power. I also conclude that none of them actually had a clue what they were writing about!

      • Gamecock permalink
        August 8, 2019 9:57 pm

        “Journalism is a profession whose business it is to explain to others what it personally does not understand.” – Alfred Harmsworth, founder of the Daily Mail and Daily Mirror

    • August 7, 2019 5:10 pm

      The Big Green marketing department simply creates articles and press releases that are copy-n-paste ready for their contacts in the media.

  5. Mikehig permalink
    August 7, 2019 3:19 pm

    Hi Paul,
    While I agree wholeheartedly with you about this drivel, I am not sure that the graph is, in fact, cumulative.
    The header does say “annual home battery installations” with the sub-header ” annual megawatts deployed”.
    Fire risk might be a concern too.

    • August 7, 2019 3:57 pm

      I was not sure myself!

    • Joe Public permalink
      August 7, 2019 5:51 pm

      “Fire risk might be a concern too.”

      It’s solar panels which arguably create the greatest fire risks:

      BRE’s ‘Fire safety and solar electric/photovoltaic systems”

      Fire safety issues

      PV arrays with string or central inverters involve DC at elevated voltages and it is not normally possible to completely isolate the DC electrics between the PV array and the DC isolation switch. Additionally, PV modules are current-limiting devices meaning fuses are not likely to operate under short-circuit conditions which could mean a fault in the system goes undetected. This scenario can present fire and/or electric shock risks,

      Fire-fighting issues

      Fire-fighters may not recognise a PV system and few know what to expect; there are a large number of different types of PV systems available and, in commercial buildings, these may be hidden on flat roofs. The new MCS installation guide [ref. 5] requires that a fire-fighter’s label be affixed in a prominent place close to the electrical shut-off point.

      Fire-fighters are not used to dealing with DC in buildings, although they have considerable experience in dealing with vehicle electrics (which are DC). There are potentially very high DC voltages (up to 1000 volts DC in large installations) which are more dangerous than car electrics and normal (AC) electrical installations.
      Parts of the system are always live while light falls on the panels (artificial lighting may generate small currents). Unless micro-inverters, or remotely controlled safety devices are used at panel level, it is only possible to shut off the building’s AC system, not the supply to the DC isolator.

      It is reported that fire-fighters in the USA are using portable covers for the PV panels in order to shut off the light supply and so prevent the generation of electricity by the panels. Heavy, densely woven fabric and dark plastic films can be effective in reducing the power to near zero, but care must be taken to ensure no light can get through the cover [ref. 19].

      • August 7, 2019 7:23 pm

        I just received a leaflet from my local authority recycling department informing me that due to two fires at their recycling depot, they were no longer taking any kind of batteries.

      • Gerry, England permalink
        August 8, 2019 1:47 pm

        It appears to be accepted practice when dealing with battery car fires to bring along a big tank of water to drop the car in for a couple of days to ensure it won’t burst in to flames again.

        Guess they might need a bigger tank for a house with a battery?

  6. Joe Public permalink
    August 7, 2019 3:29 pm

    “As usual though, she also gets thoroughly confused between CAPACITY and OUTPUT. To compare 500 MW of solar panels with a 500 MW power station ignores the fact the the former will only produce at 10% of capacity, if you are lucky and extremely irregularly.”

    That 10% -11% Capacity Factor is the average over the year.

    Throughout Januaries, our month of greatest demand, solar generates at just 2% – 3% CF, with consecutive days being overcast giving little or no opportunity for batteries to be recharged.

    It must also be remembered that there’s a round-trip efficiency loss of ~10% between charging the batteries and utilising their output.

  7. August 7, 2019 3:37 pm

    “a market with challenging economics.”

    That’s one way of putting it 😂

  8. August 7, 2019 4:14 pm

    People never really stop believing in magic, do they?

  9. markl permalink
    August 7, 2019 4:20 pm

    The more roof top solar and batteries installed the more the cost of electricity increases to pay for the operating shortfall. Those without solar+storage will be paying the difference and those with it will be paying exorbitant prices for backup ….. which they definitely will need. The real problem will be when everyone needs backup at the same time …. highly likely …. and there’s not enough available because legacy plants have been closed. Roof top solar is a diminishing returns game.

  10. August 7, 2019 4:31 pm

    Perhaps the plan here is for variable tariffs, so that you charge your lovely Powerwall when the leccy is cheap (dunno when, 3 a.m. if it’s windy) and discharge it in the evening when it is costing you a quid to boil the kettle. Of course, this only works if you have a smart meter. And if you are brave enough to have 13.5kWh of lithium battery in the cupboard under the stairs.


    • Gerry, England permalink
      August 8, 2019 1:58 pm

      During the midday period in the UK is usually lower demand but peak solar and often wind as many evenings it dies away. The mass of people are at work and most heavy industry has already shut down.

      There has been mentioned a grid access charge for the solar crew if they remain attached to the grid – what? no faith in sunshine and batteries – but fail to contribute adequately to its upkeep.

  11. bobn permalink
    August 7, 2019 5:31 pm

    Think I might start collecting old car/truck batteries (they get junked when still with plenty of life). Then build my wall with them, adding an inverter. Ok not the power of a tesla but i’ll aim for a total cost under £100 and will still run my garage tools and beer fridge.
    Given that scrap cars go for less than £50, Soon scrapped eleccy cars will be available to rob for a wall.
    Bottom line. Until the battery prices become economic this whole idea is only for those who like to waste money.

  12. It doesn't add up... permalink
    August 7, 2019 5:37 pm

    A rather more accurate version of the story:

    • It doesn't add up... permalink
      August 8, 2019 10:21 am

      Some perspective. The 6.6GWh of storage they expect to be in place across the whole of Europe by 2024 can be compared with the 9GWh of storage at Dinorwig, which only serves the UK grid. It’s tiny in the context of the pan European grid.

      I’m not sure they really have the evidence to support the claim that “Rapidly decreasing storage system costs are the primary drivers for this economic tipping point.” Tesla increased the prices on its domestic batteries a few months ago. Prices for raw materials are subject to shortage squeezes. They are on stronger ground with the claim “As the electrification epoch gets underway, infrastructure upgrades and the remnants of policies designed to address high-capex power systems will encourage electricity bills on their upward trajectory.” Though it would have been simpler to say that decarbonising electricity supply drives up costs of transmission and generation.

      So what of the UK?

      “The economic tipping points for the U.K. and France are further away, however. Both are hindered by more expensive systems on a cost per kilowatt-hour basis and unfavorable or yet-to-be-developed storage frameworks. Grid parity will not be achieved over our outlook period, but deployments are expected to continue irrespective of this.”

      No explanation is offered as to why systems should be more expensive. Perhaps what they really mean is that it’s much cheaper to run flexible CCGT and Dinorwig, but then I’m sure that would be considered off message.

      • August 8, 2019 12:25 pm

        I suspect part of it is that electricity prices in Germany and Italy are much higher than UK and France

      • It doesn't add up... permalink
        August 8, 2019 1:57 pm

        I suspect you are right, although paradoxically, the virtual elimination of subsidies to new solar installations through reductions in the export tariff improve storage economics in the UK. Of course, they completely kill the economics for solar installation in the first place, so there is no point in storage because there’s no point in solar.

        I don’t know to what extent there is TOU pricing in those other countries, or the details of how solar is subsidised.

  13. swan101 permalink
    August 7, 2019 5:38 pm

    Reblogged this on ECO-ENERGY DATABASE.

  14. Philip Foster permalink
    August 7, 2019 6:54 pm

    A Tesla battery is 75kWh, how a mere 7kW (?h) battery will be much use for EVs I’ve no idea. The Tesla battery weighs about 800kg – nearly a ton.
    Jim Al-Khalili, in his ‘Revolutions’ series, was enthusing about the prospect of electric aeroplanes … the guy’s meant to be a physicist for goodness sake –
    A Boeing Dreamliner (loaded takeoff weight about 500 tonne) would need a lithium battery weighing more than 10,000 tons.
    Excluding the battery getting off the ground (!) the thrust required is of the order of 300kN.
    take off speed around 55m/s, power required 16666kW = VI = a ballpark current for the motors around 100,000 amp…. puff of smoke and battery and engine turn into plasma!!

    • bobn permalink
      August 7, 2019 7:48 pm

      All aircraft experiments ive seen do not propose electric for takeoff or landing. The plans are for hybrids that use conventional engines to get to altitude and speed then have a rechargable battery run fans to maintain cruise (remember these aircraft are great gliders). They can cut in and augment with their conventional engines when needed. So the elec idea is just to add a little hybrid economy to fuel powered aircraft. They will cruise slower than current jets. Of course its all early ideas – no ones got a sizable one flying, though there is an all electric single prop 2 seater flying.

      • Gerry, England permalink
        August 8, 2019 2:03 pm

        So carrying the extra weight of the batteries for part time use? That makes sense. I had somebody try to convince me that diesel trains that run on partly on electrified tracks could use batteries instead of diesel. The batteries can charge when using the third rail. sounds like a lot of extra weight being carried around for part time use.

      • Gamecock permalink
        August 8, 2019 10:03 pm

        Gerry, diesel trains do run off the batteries. They are true hybrids, like the electric boat submarines. The diesel engines run generators which charge the batteries; they have no connection to the drive train.

      • Philip Foster permalink
        August 13, 2019 9:42 pm

        Sadly 2050 will put an end to that. No more hybrids allowed!

  15. Harry Passfield permalink
    August 7, 2019 7:53 pm

    On top of the costs of solar/battery installation there is the small item of home insurance. I bet the actuaries would have something to say about that.

  16. Pancho Plail permalink
    August 7, 2019 10:51 pm

    I want to follow up the issue of comparing the batteries to power stations.
    The batteries are rated in kWh, and using their rated value they will output that for one hour, eg a thousand 5kWh batteries will output 5MW for an hour, after which they cannot be used further until recharged.
    Meanwhile a 5MW power station will generate 5MW hour after hour.
    So even assuming that the batteries can be fully recharged each day they actually store 5MW per day, whereas the power station produces 120MW per day.
    It is quite specious to compare the two in the way they have.
    On a technical note, the batteries used are Lithium Ferrophosphate which do have a reputation for long life and are the go-to battery for off-grid installations. The Tesla batteries are, of course, the most expensive option. Alternative Sonnen batteries are nearly 20% cheaper.

    • Dave Ward permalink
      August 9, 2019 10:12 am

      “The batteries are rated in kWh, and using their rated value they will output that for one hour”

      The Amp/Hr figure of batteries is dependent on the rate of discharge – traditional lead/acid (e.g. car) batteries are normally given at the “20 hour rate”. This means a 100ah battery would provide 5 amps for 20 hours, but it DOES NOT mean it can give 100 amps for one hour! The greater the current being drawn, the less capacity will be available. It’s not like drawing water from a tank – there are chemical reactions involved, and resistance to take into account. You will get back some residual capacity from a battery which has been heavily discharged, but only by waiting for a time. Anyone who has “flattened” a battery trying to start a reluctant vehicle will know this – walk away and come back after 10 minutes and it will have recovered enough for a further attempt. Lithium chemistries are less affected, but they still won’t give the full rating during heavy discharges. The same thing applies in reverse, when charging, so your example is actually unnecessarily generous! The reality is that a 5MWhr battery is in no way compares with a 5MW traditional generator, except for very short duration high current delivery.

  17. Pancho Plail permalink
    August 7, 2019 11:01 pm

    It is worth pointing out that in addition to VAT of 19% on electricity German consumers also pay an additional 7% eco tax.

  18. Bruce of Newcastle permalink
    August 7, 2019 11:59 pm

    A spate of battery fires have caused Lyft to pull their electric bikes out of San Francisco a few days ago.

    You’d have to think the risk of fire is quite real for in-house batteries too. I wonder what insurance companies think about that?

  19. Coeur de Lion permalink
    August 8, 2019 9:14 am

    As I sit here eating breakfast the BBC Radio 4 Today programme is wittering about the annual awards for journalism. Is there one for wilful leftist stupidity?

    • Gerry, England permalink
      August 8, 2019 2:14 pm

      Be tough to just single out one for that one.

  20. August 8, 2019 9:15 am

    a 5KW Powerwall battery will set you back £7750, plus installation of up to £2800

    Strictly for people with more money than sense.

  21. August 8, 2019 12:38 pm

    Reblogged this on ajmarciniak.

  22. Gerry, England permalink
    August 8, 2019 2:16 pm

    Reading CityAM the other day there a piece saying that a mine was closing due to falling cobalt price. As this is an essential part of batteries what is going on? I know the vast majority goes to steel production so it could be that driving it.

  23. JOHN SMITH permalink
    August 8, 2019 3:51 pm

    The scam is all in the subsidies. Personally, I can see no problem with solar & battery storage as long as the user pays for it and does not expect the rest of the population to cough up through subsidies & tax breaks. I have solar, wind & battery storage. I put it all together and it works quite well. I am not entirely sure about the economics of it, but it is fun to do and it does give independence in a place where power cuts are common and it means that I don’t need to run my generator. There seems to be a lot of quite cheap solar panels around. Could be something to do with the cut backs in subsidies.

    • Dave Ward permalink
      August 9, 2019 10:22 am

      “As long as the user pays for it and does not expect the rest of the population to cough up through subsidies & tax breaks”

      Exactly! I would certainly look at doing it myself, if I lived in a (fairly) out of the way location. But the long term economics do need to be looked at: batteries have a limited lifespan, and so do switch-mode inverters & chargers – the electrolytic capacitors are usually the culprits. I’ve already knocked up a basic battery/inverter system to give me several hours autonomy if the power goes off, with chargers and a genny for longer periods.

  24. Gamecock permalink
    August 8, 2019 10:06 pm

    ‘The UK risks being left behind in Europe’s home battery boom’

    A race you don’t want to win.

  25. August 9, 2019 3:27 pm

    The #PioneerFallacy : dumb pollys want to say UK is “WORLD LEADER in X”
    meanwhile smart countries hold back and learn from the mistakes UK pays for
    eg. High rise housing etc.
    Get-it-Right not Get-It-Rush

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