The Energy Return of Solar PV – a response from Ferroni and Hopkirk

Last week’s post on The Energy return of Solar PV caused quite a stir. Yesterday I received a response to some of the comments from Ferroccio Ferroni and Robert Hopkirk addressing some of the queries raised by readers. Their response is given below the fold. But first I have a few comments to add.

Let’s kick off with the unshakeable enthusiasm for renewables of every flavour from the Scottish National Party. Member of Parliament Callum McCaig (inset pic):

I think Scotland is very much leading the way….

….in how we embrace the renewables agenda… whilst we have a government who seem to be investing in the white elephants of Hinkley and, at best, 1950s technology. It is not a lost cause but we do need to keep beating the drum for solar, for wind, for storage and we get these things right we can say cheerio to things like Hinkley Point C.

Solar in Scotland produces virtually no electricity in the winter months, it produces absolutely zero electricity at 18:00, the time of peak demand in winter (Figure 2). Bridging the annual solar cycle with storage is impossible (at least totally impractical). Hinkley C, despite its many flaws, would provide 3.2 GW of power 24/7 and it is cast as a white elephant! The political commentary on energy in Scotland has become dangerously deluded.

Figures 1 and 2 UK solar output according to National Grid for June 2015 (top) and December 2015 (bottom). Both charts at same Y-axis scale are taken from UK Grid Graphed. UK wintertime solar is totally useless as a power generating technology producing a pathetic midday blip. According to DECC the UK had 8.14 GW installed PV capacity at the mid-point of 2015 and 8.92 GW at the end of 2015. In December, those 9 GW of installed capacity pushed out 0 GW of electricity for most of the time.

But do we know how much electricity solar PV is generating in the UK? We can download data from National Grid or DECC but what does it mean? Most domestic PV systems do have meters that evidently are not read. I checked with the Renewable Energy Foundation who were of the opinion that UK PV generation was model based. In other words synthetic data based on model inputs. And this is DECC’s description of UK solar PV production statistics:

Note 6. Actual generation figures are given where available, but otherwise are estimated using a typical load factor or the design load factor, where known. All solar photovoltaic generation is estimated this way.

Despite what many may think I do not have an axe to grind on solar PV. If it can be shown to work unsubsidised with ERoEI >>5 then fine. But if it is true that high latitude PV has ERoEI approaching 1 then we are digging ourselves an energy grave. The book by Prieto and Hall on the ERoEI of Spanish solar PV, and this excellent pdf summary, settled on a figure of 2.4 for a capacity factor of 17%. Normalise that to a capacity factor of 9% for high latitudes like the UK and the ERoEI comes out at 2.48*(9/16) = 1.4 and Prieto and Hall do not account for the energy cost of intermittency. Take that into account and their number is not a million miles away from the controversial figure of 0.83 reported by Ferroni and Hopkirk. And please note that ERoEI for solar PV is not a constant but varies with latitude, sunshine hours and orientation of installation. It seems in the UK at least that we do not have reliable figures for the energy return part of the ERoEI equation.

And so to the response from Ferroni and Hopkirk:


To the blog:

Dear contributors:

We are clarifying here our position regarding the objections raised in this discussion-panel:

1) The value of the PV-electricity production in Switzerland during the lifetime is too low and PV-systems are producing per year much more electricity (as much as 153 and up to a value of 185 kWh el/m2 have been cited in other comments). We give a value of 107 kWh el/m2/year and with degradation, a lifetime value of 2203 kWh for 25 years. One should note that also PV modules integrated in building façades are included in this average.

  • We base our value on the Official Swiss Statistics and we explain how to use it. The weak point of the all PV- statistics is that they are not based on the module surface but on the fictive value of kW peak. This was enforced by the solar industry in order to confuse the results. On the other hand, the value of the energy absorbed in thermal collectors is given per unit surface area. Going to the statistics one obtains the total energy produced up to the end of the corresponding year (normally in GWh) as well as the total installed capacity or power in MW peak as direct current at the end of the corresponding year. Dividing MWh by the average capacity between the end of year and end of the previous year we obtain MWh / MWp. We assume here that during the year a linear capacity increase due to the construction of new PV-plant is to be expected.
  • Here we have to distinguish between the value indicated by a module supplier and what is used in the real planning of PV-Systems. Modules are sold on the basis of money per peak Watt, which is understood to come from a reference sunlight intensity of 1 kW/m2. If the conversion efficiency were perfect, the area of the module would be 1 m2. For a conversion efficiency of 20 % the required area would be 5 m2. But efficiency is measured at a standard temperature of 25° C and a vertical radiation incidence of a lamp, that cannot simulate 1 to 1 a solar radiation. We suggest measuring efficiency at an incidence of 45 degrees inclination and at a temperature of 40 °C and this would correspond more closely to reality, the resulting efficiency then being much lower. In real planning other values are used: In Germany a value of 10 m2 per kWp is used (information from insiders – i.e. from people working in the field) and in Switzerland, Swissolar is recommending also to plan PV-plants with the same value. This means that, when in Germany one will obtain 1000 MWh/MWp from the statistics and then, dividing by 10 m2/kWp, 100 kWh/m2 of electricity production. In our case we have made an average over the last 10 years, but we have used a conservative value of 8,2 m2 pro kWp to determine the electricity production. The value is based on the evaluation of projects realized in Switzerland where previous projects were planned with 8 to 9 m2 per kWp.
  • I have been in front of a court to deal with the question of declaration of the payback period of PV-Systems. I had stated that the average specific performance value is 100 kWh/m2 without degradation. The utility did not claim that my assumption was wrong. Therefore, our value of 106 is court-proof.
  • One utility has forbidden us to publish results and I suppose that they were below 100 kWh/m2.
  • When I was asking some utilities to give me measured results for publication, I received only the project data, which usually indicates that these values are higher than any measurements. All computer programs for the calculation of the production give results, which are too optimistic.
  • We have assumed an average lifetime of 25 years. We have however, insider information claiming that a lifetime of only 20 years is more realistic.

In conclusion, we are aware that some PV-plants produce much more than our average. But we are confident that at the present stage of development our average value is conservative and of course we are not appreciating the non-transparency of the utilities.

2) Energy involved in labour and capital: In our paper we have demonstrated that PV generation is both labour and capital-intensive – for labour by a factor of 7 and for capital by a factor of 10 in particular with respect to nuclear energy. We know that the current life cycle analysis does not consider these two factors. As a result, the activities related to the PV are producing a destruction of resources without being able to satisfy any of the energetic needs as given in form of a pyramid going from extract energy to arts in the papers of Hall/Prieto. It is similar to digging out a hole in the earth and then, when finished, filling it again, but even worse, not completely. Could one explain me the benefits to our society of such an operation? This is in our opinion unethical, since you are not only allocating but worse you are diverting resources to the real need of the society which are for instance the elimination of the poverty. PV in region of moderate insolation are increasing the poverty or destructing wealth. We are of course welcoming similar calculation also for the nuclear or fossil field.

3) Price data: As commented, Switzerland is an expensive country. Our study is uses Swiss data. The value of 6000 CHF/ kWp – the average of the 5000 to 7000 is from Swissolar, the lobby association of the solar industry. It is always difficult to compare prices: Looking at at the Sunroof Project of Google for California, you will find at the moment a value 4100 USD/kWp. Knowing that our hourly rates are higher than in US, we judge the assumed value to be reasonable. But the capital cost of 1000 CHF/ m2 indicated in our paper for a mixture of 2/3 roof-mounted and 1/3 field-mounted installations is – in our opinion – too low. Note that land in Switzerland is very expensive. Therefore, we have calculated a low capital requirement. In reality more capital will be needed. Our results should be considered as conservative.

4) References: one comment was related to old references (2009) regarding the weight of the supporting material. To size a support one needs to perform a stress analysis considering loads such as weight, high-winds and earthquakes. Stresses remain stresses and also allowable stresses have not changed in last 100 years. Of course it would be possible to provide newer references.

Many thanks to all contributors for their comments and for new references received. Some were new to us. After this interesting discussion, we remain of the opinion that photovoltaic technology, at least for Switzerland and Germany, is leading our society towards an enormous destruction of resources. In this connection we see elements of questionable conduct from some politicians, against which the civil society should counter-attack. Note that in our paper we have limited our study to the energy, without considering the emission of CO2. We have published in German an article showing that a modern coal plant emits fewer greenhouse gases per unit of electricity than does a photovoltaic plant.

Ferruccio Ferroni/ Robert J.Hopkirk



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65 Responses to The Energy Return of Solar PV – a response from Ferroni and Hopkirk

  1. Euan Mearns says:

    I’m interested to have feedback from UK and European readers, who own rooftop solar arrays, on how their generation is recorded by utilities and on what basis are subsidies paid?

    • Euan

      I do not have one but I understood that the FiT payment was based on the installed projected power production, index linked and 50% for export with 50% for use. I am sure I saw that in case studies on domestic via DECC. Had a quick look but no joy but did see the 50/50 in this link.

    • Dave Rutledge says:

      Hi Euan,

      This is for New Mexico, not an EU country. My cumulative solar generation is available on a meter on my house, but it is not available to the utility unless they drive their truck up into the mountains to see the meter.

      I have net metering on a monthly basis. However, if we are not there, we only get avoided cost, which is 3 1/2 US cents/kWh. My dollar payback time is a hundred years.


    • Colin Appleyard says:


      We were fairly early adopters of the UK domestic PV scheme. Our roof-top installation consists of 16 panels with a rated output of 3.84kW. The roof is at the optimum slope for our location in Southeast England, but the array faces roughly SSE and is partly shaded by deciduous trees in the mornings.

      Our annual output has averaged 2700kWh since April 2011, but this fluctuates a lot more than I expected, the range being 2060-3457 kWh. The installation cost was about £14500.

      The tariff we enjoy is currently 48.84p/kWh for generation, and a further 3.44p/kWh for exported power. In the absence of an export meter, we are deemed to export 50% of our generation. These figures are adjusted with RPI, and guaranteed for (I think) 20 years. We provide a meter reading once every three months, and get paid 3 months later.

      Overall, I’m satisfied with the performance, albeit about 10% less than the salesman predicted- but I had discounted his figures by 15%, so I’m ahead!

      • Euan Mearns says:

        Thanks Colin, but I’m surprised that you don’t have two meters, one for total production and one for export and that the guy who comes round to read your ordinary meter doesn’t simply read your PV meters at the same time. And if you send a meter reading to your utility why are DECC evidently using a model and not actual generating statistics?

        • Colin Appleyard says:

          An export meter probably doesn’t make economic sense at the level of domestic installations, considering the cost of the hardware and the data management to calculate the value and issue a specific payment.

          We get an email requesting a consumption meter reading every quarter. The guy who reads the physical meter only comes round once every two years or so- probably mainly to audit our readings.

          And why DECC model rather than use actual data? I’ll just say “dunno” rather than launch into a tirade about technically incompetent government departments.

      • We have a similar sized array, just north of Inverness, which has been operational for about 4 years.
        I can confirm the metering arrangements – we were quite keen to have an export meter because I was pretty sure we wouldn’t use anything close to the 50% assumed domestic consumption, but we were told we’d have to pay a considerable annual service charge for the meter. (We then bought a cheap kWh meter and installed it to measure exports anyway, and found we actually use about 16% of generation).
        Our average annual generation is about 3,500 kWh/ yr, and I gather from a friend in Devon that the output from their array was 4,370 kWh in the first year of operation. I think modern panels have a better response to relatively low light levels – and as they are considerably cheaper than a few years ago (recent quotes of £5,500 for a 4 kWp roof-mounted array around here), they are presumably much less energy and labour-intensive in manufacture. So I think the ERoEI calculation would be quite a lot more favourable to PV if it was based on current data rather than historic.

        • Euan Mearns says:

          Martin, thanks for this, assuming you have a 4kW array I calculate you have a 10% capacity factor which is high. So I’m assuming your array is well-aligned and you keep it clean. And if you are close to The Black Isle, its a sunny spot. Those that comment here tend to be PV enthusiasts who make sure things are done right.

          When you say you use 16% of your generation, presumably you live off the grid at night and in winter and export most of what you produce in the summer?

          I’d agree that new modules are perhaps much more efficient in the way they are made, but I’m still wary of conflating price with cost.

    • There is one big plant outside the city Västerås that you can study.
      It is 1010 kWp, 6552 m2 on 40 000 m2 of land.
      Year MWh kW
      2015 1210,7 912

  2. I don´t understand the price data estimates. What does the 6000 CHF include? Sweden is also an expensive country and plug-and-play installations (including labour and mounting-structures) are only a third of that price (per kWp).

    • Euan Mearns says:

      Daniel, I asked Ferroni and Hopkirk to provide links to price and load factor statistics but they were unable to do so in time. I tried to find the load factor statistics from the original article but couldn’t. Googling a foreign language is a problem.

      Swiss Federal Office of the Environment – Climate change in Switzerland – 2013. (Schweizerische Eidgenossenschaft, Bundesamt für Umwelt, BAFU – Kli- maänderung in der Schweiz – 2013).

      The main interest for me here is really the ERoEI and allegations of improper behaviour by the solar industry and by politicians that I removed from the text. I have today emailed DECC in the UK asking for details of how solar generation is recorded and on what basis subsidies are paid.

      Forroni and Hopkirk are to large extent backed up by Prieto and Hall who provide much detail. You should have a look at the link I provide.

      My interest also flows from what I see here in Aberdeen where we can go months without seeing The Sun and in winter The Sun just pops up above the horizon for a few hours, and solar panels are bolted on to any roof regardless of orientation. And I think building regulations stipulate that all new houses require solar panels to be mounted. And David MacKay alluded to the fact that a political decision was made against the technical advice.

    • gweberbv says:


      Ferroni and Hopkirk are stating prices for residential installations (for what reason ever). These prices will cover a very broad range. You will always find an electrician who tries to sell a PV system to uninformed, but well-off people for a phantasy price. Moreover, some people want to have a special type/design of PV cells that fits better to their house.

      Here is a recent offer from one of the bigger PV installers in Germany for residential customers in Switzerland (German speaking part):–t110842.html%3Fsid%3D81b9b43141618189cc29ee53c34a1285&edit-text=
      Probably, this has to be regarded as a competitive price tag for Switzerland.

      But such small systems (typically < 5 kWp) are of course irrelevant, when one wants to discuss PV penetrations levels (every single kWh produced from PV has to go through a hydro storage plant) that can only be achieved with utility-scale installations.
      When we discuss PV plants with more than 1 MWp capacity, we talk about serious investments and not calling the electrician next door and to ask him what he would like to have for a few kWp of PV.

      • Daniel says:

        Thank you. The price level of one third in Sweden is relevant for installations in the 10 kWp-range. My point is that if this data is so far of the mark, one might start questioning many of the other assumptions. Which would be à shame.

        • gweberbv says:

          All assumptions were made with a single goal, I suppose: Ending up with a negative ERoEI while keeping all parameters not more than a factor 2 or 3 away from state-of-the-art values (which translates into ‘to be in the right ballpark’.). It did not work out, so on top we put the assumption that each kWh of PV electricity is saved in a hydro storage plant. And of course not an existing one, but a new one that was built for no other purpose than to destroy 25% of PV production (assuming 75% efficiency of the storage plant). An finally we find ERoEIext < 0. Mission accomplished.

          • robertok06 says:

            “”so on top we put the assumption that each kWh of PV electricity is saved in a hydro storage plant. ”

            Dumbest comment you couldn’t make, Guenter, and dumb comments you have made in quantities, recently… Switzerland, after Norway is the european capital of pumped hydro… what other storage option should they have assumed?

            In addition, it is well known that the existing pumped hydro is nowhere near sufficient to store the ele
            C’mon, wake up!

          • gweberbv says:


            the hydro plants that Switzerland already have will not consume additional energy when storing PV production instead of nuclear production (or more general: cheap baseload production during the night).

            And additional capacity – if needed – will be very limited due to technical, environmental and economical constraints.

            So, either you already have the necessary hydro storage capacity for PV or you will never get it because it is not possible to build it. Resut is the same: Zero energy costs.

          • robertok06 says:


            the hydro plants that Switzerland already have ”

            No. Switzerland has an amount of pumped-hydro storage capacity which has been designed to store over ONE night the “excess” electricity of nuclear power plants which are not modulated but left running at full steam… a COMPLETELY different amount, much bigger, of pumped hydro storage would be necessary to store over a timespan of MONTHS the “excess” electricity generated by PV in summer to be used in winter.
            I have already explained this to you how many time already?…. and yet you, sorry to say it, trollishly keep on “forgetting” it. What for?

          • gweberbv says:


            nobody will store PV during summer for the winter in a newly installed pumped hydro plant. Nobody, nowhere, never.
            PV and wind will make use of what is already there and that’s it basicly.

  3. Thinkstoomuch says:

    Thank you all three for this response!

    While not exactly on point this relates to politicians at least in the US. An EIA evaluation of one of our current programs.

    Thanks again,

  4. Willem Post says:


    Germany likely has more accurate data regarding solar generation than most other nations, because each household rooftop system has two smart meters; one to transmit the entire production to the utility for calculating feed-in tariff reimbursement, and one to transmit to the utility the owners consumption.

    That data is aggregated and periodically published on government websites.

    Based on the ideal national average solar CF of about 0.12, the published actual production yields a CF of about 0.10, which means a loss of 100*(0.12 – 0.10)/0.12 of about 17%, on a national basis.

    This includes aging of the installed PV capacity, and all other detractors from ideal conditions.

    Some countries are less zealous about data, and likely also less zealous about the correct installation of systems.

    The loss percentage of those countries may be greater than 17%.

    • gweberbv says:


      you are right for the past, but in the future German data will be less useful. The reasons are as follows:
      1) As PV production costs fell below the retail rate, self-sonsumption becomes important. This is not measured directly, but could maybe determined from the change of electricity demand during the PV peak when compared to the situation a few years ago (when it made sense to feed all PV production into the grid).
      2) Since a few years it is mandatory to either curtail PV production at 70% of nameplate capacity (in Germany and with non-perfect orientation/tilt of the PV cells this leads to a loss of only a few percent of annual generation) or to install a device that allows the grid operator to do the curtailment when it is necessary.

      • It doesn't add up... says:

        It seems like and extraordinary scam if you’re only allowed to use 70% of your installed capacity. Perhaps Germany’s capacity statistics ought to be adjusted downwards to reflect that.

    • MuellerB says:

      Willem this information does not become more true by repeating it. There is no generation measurement in germany, just the surplus is measured in almsost all systems

      • Willem Post says:


        1) That means, for many systems, self-use is subtracted from generation and the surplus is sent to the grid, measured and compensated at the feed-in rate.

        That would appear to understate German solar generation for those systems. The self-use part would need to be estimated to obtain all generation.

        When the feed-in rate was very high (much more than the electric rate), it paid to have many panels on a roof.

        Now that the feed-in rate is much lower (much less than the electric rate), some owners may think about battery storage.

        However, the storage cost/kWh would make that option unattractive, unless at least 50% of the capital cost of such storage systems would be offset by a subsidy.

        2) That means, the generation of larger-capacity systems, with minimal self-use, is send to the grid, measured and compensated at the feed-in rate.

        That would be the only part of German solar generation that one could be sure about.

        3) In any case, solar generation is significant for a few hours of around noontime.

        As shown by above graphs, most of its presence is during summer; it is nearly absent during winter.

        The ERoEI of such energy, in terms of usefulness to sustain a modern economy, is next to nothing, and may even be negative.

  5. Euan,

    Can you comment on this story please:

    As always I’m very suspicious of headline features like this as they are invariably covering over the small-print.

    Thanks – John

    • Euan Mearns says:

      Basically good for Portugal. Portugal has a relatively small population in a relatively large amount of space and they have quite a bit of hydro. To have hydro to balance wind and solar is a good place to be for renewables enthusiasts.

      To put things another way. Norway running on 100% renewables for 40 years wouldn’t make the headlines.

      I think Roger may write a post on Portugal.

  6. Ajay Gupta says:

    Thanks for the post!

    Some points I want to share:

    1. “This was enforced by the solar industry in order to confuse results.” Seriously?
    2. This study is very geography specific as is PV in general. Original EPIA scenarios place almost all European PV in Northern Africa, and preferred CSP. Germany seemingly got sick of waiting and went ahead on there own?
    3. Every EROI study I know or helped to produce myself is aware and articulates in some fashion that the true EROI is likely lower than reported. This is especially true of fossil fuels and nuclear.
    4. If I heard correctly, Murphy et al are preparing a rebuttal to the original paper but don’t quote me on that.

    For the record I’m am very excited about the interest in EROI these days! But please note EROI work has always been hampered by bad/incomplete data and no funding.

    Thanks again!

    • Euan Mearns says:

      I know one criticism Dave Murphy had of the Ferroni paper was the very broad boundary they placed which made it non-standard and difficult to compare with other studies. That led to a 40 odd email exchange with Nate and Charlie. I like the idea of extended boundary and do suspect that the ERoEIs of other sources including oil and gas are too high because they do not capture a sufficient level of energy invested in the extended system.

      • Ajay Gupta says:

        I agree the broad boundaries can be a problem, but it was how the information was communicated that created the big stir.

        First, this paper was immediately picked up by the nuclear advocates such as BTI and disseminated through social media accordingly, whereas EROI has not really been their “thing” in the past.

        Second, when Prieto and Hall used similar boundaries in their book, they first started where others did before them, and incrementally moved the boundaries out one step at a time. Thus their information was truly novel and useful, whereas this new paper has lead to some serious confusion out there both in terms of what it means and how it was developed.

        Overall I’m still glad to see this and look forward to more!

    • Leo Smith says:

      If it were not for subsidies, we would not need to look at EROEI.

      Using captured slaves on treadmills to generate electricity is at a competitive disadvantage to using captured slaves to drill for oil to be burnt in diesel engines. This way we know which is the better EROEI.

      Only when you destroy a free market by subsidies, do you need to calculate EROEI to determine whether or not you have reached Peak Insanity.

      • Euan Mearns says:

        This is true. But taxation also distorts the economic picture. All those tax subsidies paid by the FF industries represents net energy as does the profit and dividends paid.

      • Ajay Gupta says:

        As Dr. Means points out, there are a lot of policy vehicles in place; but also technology and infrastructure in place. For me EROI has been invaluable in teaching the people I care about the realities of the energy systems and the apparent misinformation concerning sources such as shale or tar sands, for example. Ethanol was easiest to explain.

        Most important are the EROI trend lines and what they tell us about our economic and political futures (for me). For others, especially engineers in my limited experience, they often just assumed that EROI must be positive because duh and that’s all you needed to know. As for free markets, don’t you need an informed public? That’s what EROI is all about!

        Here is an important piece on why EROI matters from years ago. Personally, I find that the questions here are still relevant today:

  7. Ikemeister says:

    Thanks for relaying their response. As Ajay notes, it’s good to have ERoEI analysis results being shared. Certainly there’s a danger of GIGO (as with any analysis) but the more eyes on this methodology, the better.

    We have published in German an article showing that a modern coal plant emits fewer greenhouse gases per unit of electricity than does a photovoltaic plant.

    I for one would be very interested in reading a translated version.

    • Euan Mearns says:

      This was also a point I made in my original post. It follows from ERoEI < 1 and panels made in China where most energy comes from coal, oil and gas. More CO2 will be emitted in China to make the panels that will be saved by their CO2 free operation in Europe. European governments are allowing their heavy industry to close and then make believe that CO2 emissions are reduced even though the same goods and materials are being fabricated in China where emissions are rising much faster than ours are falling.

      • Ajay Gupta says:

        I would also add this should get worse over time as the less energy intensive materials are used up first – unless we start moving towards 100% recycking rates, but even then might not change things enough.

  8. Mikey says:

    Price level really is completely wrong. I am in the solar business in the Netherlands and we sell plant for around €1,10 /Wp ex VAT on roofs, turn key and the price for ground mounted is below €1/Wp. This means that the value is a magnitude of x6 wrong. So close to about ERoEI = 5. Also the production is too low. A reasonable azimuth system with new modules of around 280Wp produces at least 140W/m2 (without degradation). We have to give warranty on the performance so this is not up for debate. I am willing to go to court to prove 106W/m2 is false (based on a new system).

  9. Grant says:

    Surely there is a very circular discussion to be had on EROI in any form.

    For example part of the total concept and resulting policy decisions for Ecological conservation is re-cycling and at this stage that is, so far s I am aware, a rather expensive exercise to support being somewhat energy intensive one way or another.

    We carry costs now to “save” future generations from costs they may never come to see. Indeed half the arguments about about favoured developing technologies becoming cheaper in a short development period (in human terms) might suggest that the materials being recovered to save depletion may not be relevant by the time level of depletion would matter.

    Then there are potential unaccounted though potentially expensive costs that will never be considered specifically.

    As we are talking Solar PV I’ll put forward some related observations.

    There have been a couple of reports of house fires where Solar panels were either thought to be part of the problem or prevented firefighters deploying their usual well defined procedures.

    If you have a standalone house that would be a form of risk shared between you and your insurance company.

    If you live in a property with a shared roof and the other party or parties to the roof are not also parties to the Solar panels but are adversely affected by any problems caused to or by the roof installation, there is a cost risk that is unlikely to be associated with the cause when analysed.

    The risk may well not result in actual damage or loss …. but whether the insurance industry will ignore the opportunity to increase premiums for whatever reasons they can dream up remains to be seen.

    The risk cost need not relate solely to disastrous losses like fire. Extra stress and wear and tear on a shared roof could be just as costly yet less obvious.

    At the industrial scale there may be different costs.

    I am aware of of a situation where a field was converted to a “Solar Farm” status. The field is next to a small semi-rural industrial estate that is home to a number of small businesses.

    As the work finished – in a wet period of the year – the Industrial Estate premises were partly flooded by muddy run-off from the Solar “farm” field. The costs and disruption were, of course, borne by the businesses on the estate. No previous problems had been experienced in several years of operation at the location which is in a generally rather flat part of the country.

    At another flat location, a former airfield now used mainly for leisure activities, what had been arable field growing crops was recently converted to a Solar “farm”. Soon after completion of the work a slightly wet couple of days resulted in never before seen flooding of the facility causing a weekend of business generating activities to be lost. Many people who had used energy to travel some distance to the location lost out.

    Presumably such problem relate to soil compaction. Does that man they are a one-off event diectly related to the engineering work undertaken? Or will the change of used, from open field to industrial scale Solar Array indicate continuing potential for regular weather rlalted disruptions?

    I expect there will be quite a few similar examples that will occur but never reported widely in the public domain. The costs will be absorbed by those outside the industry and so will be lost in the noise.

    • Leo Smith says:

      Soil compaction is probably a secondary effect: What counts is loss of plant life. Why do we stand under trees in the rain? Because they dont let the rain hit the ground until a zillion tiny leaf sized puddles are full.

      And they continue to drip for some time after the rain stops. Plants BUFFER water. Solar panels dont.

    • Dave Ward says:

      “Presumably such problem relate to soil compaction”

      I very much doubt it. Far more likely is that a large part of the field is now covered by impervious panels, and the area underneath them doesn’t see rainfall directly. However, the rain which now falls on the panels runs off between them, and that (much smaller) area can’t absorb it quickly enough to prevent run-off to adjacent fields. The covered soil changes in constituency quite quickly into a hard surface, very different from how it was before. Much the same effect occurs in built up areas, where people tarmac/pave over their front gardens to create parking spaces or simply to reduce maintenance. Heavy rain now leads to serious flooding, as we have seen over recent years in the UK

  10. Stuart Ellison says:


    Let me start by saying something outrageous, not all kilowatts are equal.

    A kilowatt of power is more valuable at 6pm than a kilowatt of power at 4am.
    A kilowatt of power is more valuable at the point of consumption than at the point of generation.

    If not all kilowatts are equal then it is folly to compare them. Different scenarios are best served by different solutions.

    The most efficient way to get the best solution for each scenario is to let the market arbitrage its way to continuous optimisation. This is what we used to do and it worked extremely well.

    However, the challenge now is that emissions are widely accepted as contributing to an extremely large future liability (climate change). Combustible power generation with emissions is another case of privatised profits and socialised liabilities (just like banking).

    It’s a textbook case of the market failing to recognise a potentially important consideration for capital allocation. The risk of a very large future liability being borne by wider society.

    Subsidizing turbines and PV and other silly venture is the State’s way of trying to circumvent capital allocation to a more desirable/favoured mix. But subsidizing broken solutions does not help humanity find a workable solution to the problem.

    What the governments need to do is to address the problem which is that emissions pose some kind of risk to the future. What the government should do is levy a carbon tax on all CO2 emissions. Something of the order of $20/tonne.

    This tax can be used by governments to purchase climate change insurance. Yes I am serious.
    If climate change becomes more likely then the insurance premiums will rise and the governments will have to raise their carbon tax in order to continue purchasing the necessary insurance. If the risk of climate change falls then the premiums will fall and the governments can reduce the carbon tax.

    This is a self regulating policy. It works. It uses capitalism. It does not require any individual or institution to micromanage our destiny. It empowers the market to do what it does so incredibly well. To serve humanity everything we need.

    It also leaves the door wide open for any kind of future energy technology and doesn’t unfairly crowd out innovation by preselecting solar and wind as our must have solution.

    • Grant says:

      It removes all doors, most walls and the roof.

      The world if mandated insurance is, being fully supported by rapacious types who see the benefits of political power, somewhat worse than the banking system.

      No problems (assuming some that are solvable can be clearly identified) would be solved but decisions that simply shuffled the deckchairs in one direction or another would be made for monetary gain. Another ponzi scheme that revalues the distribution of money without fixing any allaged problems let alone any real problems.

      If the world decides there is a genuine problem to solve and that it can only be solved by moving to a totally “carbon free” society then the habits and expectations of the population would need to change.

      It gas happened in some places before. In fact the developed world must have been functioning in quite different way before the industrial revolution.

      Behavioural change along similar lines that adapted to “free” energy would make more sense and likely prove to be more acceptable to more people than some sort of theoretical scheme that could be readily abused by a handful of people for their personal advancement. Also far more likely to have some beneficial effect – assuming such an effect can be observed and is certain to be advantageous in some way.

      • Stuart Ellison says:

        I have no idea what you are trying to say. Are you a teacher?

        • Grant says:


          Are you a student?

        • Grant says:


          Let me see if offering corrections for a few typos helps.

          “The world if mandated insurance ..” should of course have been “The world OF mandated insurance …”

          “allaged” should be “alleged”

          “It gas happened ..” should be “It HAS happened …”

          The final sentence would be better written as

          “Also it would be far more likely to have some beneficial effect – assuming that any effect would be observable and would also be certain to be advantageous in some way. Such a result may not be guaranteed in any random set of circumstances ini a chaotic system.


        • Grant says:


          Let me see if offering corrections for a few typos helps.

          “The world if mandated insurance ..” should of course have been “The world OF mandated insurance …”

          “allaged” should be “alleged”

          “It gas happened ..” should be “It HAS happened …”

          The final sentence would be better written as

          “Also it would be far more likely to have some beneficial effect – assuming that any effect would be observable and would also be certain to be advantageous in some way. Such a result may not be guaranteed in any random set of circumstances ini a chaotic system.


    • Leo Smith says:

      This is a self regulating policy. It works. It uses capitalism. It does not require any individual or institution to micromanage our destiny. It empowers the market to do what it does so incredibly well. To serve humanity everything we need.

      The above are exactly the reasons why it is politically unacceptable and has never been adopted.

      Governments are not in the business of enacting legislation that results in less need for government.

      Government has to be seen to be an essential and necessary part of any solution, to justify its continued involvement.

      Remember too, that the only people who are really interested in politics are the more or less hard left: They are the ones who drive ‘progressive’ agendas, and their belief, is based on Marxist philosophy, and Marx broadly states that the natural progress of society is from free markets with capital and labour, to unfree markets dominated by a communist state machine, to a post industrial Utopia.

      And Climate change is a useful tool to pout their useful idiots (the academics and the wannabe Important People) to work building that all encompassing Superstate.

    • Euan Mearns says:

      A kilowatt of power is more valuable at 6pm than a kilowatt of power at 4am.
      A kilowatt of power is more valuable at the point of consumption than at the point of generation.

      Agreed. Dispatch is a really important attribute of energy quality. I’m writing a overview post that I hope is good to go Monday. But there are a large number of mind-bending aspects of ERoEI. Take for example paraffin burned in a stove. It converts to heat at about 100% efficiency. But gasoline burned in a car converts to motion at about 30% efficiency.

    • Willem Post says:


      The most efficient way to get the best solution for each scenario is to let the market arbitrage its way to continuous optimisation. This is what we used to do and it worked extremely well.

      Right you are, about the past.

      However, politics-inspired RE subsidies have totally distorted the market place, i.e.,
      that “most efficient ” way is gone.

      More CO2 may not be as bad for many people.

      Here in Vermont, warmer winters are saving heating costs, and the summers are less warm than in the 1950s and 60s.

      That may not be true in the rest of the world.

      However, the world has too many people, and too much of a destructive world economy anyway.

      So, if we lose those two excesses, so be it.

      Less of fossil fuels would be used. They would last longer.

      Less capacity of RE systems would be needed.

      Supporting 9 to 10 billion people by 2050 with RE systems would be impossible anyway.

  11. Dr Ken Pollock says:

    Fascinating comments on floods from solar farms. Surely the real problem is concentration of runoff from the whole solar panel on to a linear strip at the panel’s bottom edge, thus overloading the soil capacity to absorb the rain at that point. Vegetation would help impede the runoff, but would be operating over a fraction of the area on which the water falls – and immediately after installation, that section would indeed be compacted and the vegetation damaged.

    Installing drainage channels to intercept the runoff would be expensive but not impossible – might just upset the economics, though!

    Re the energy balance equation, we are familiar with the years taken to “pay back” the energy needed to construct any power station. I once asked a manufacturer of off shore wind turbines what that payback period was for his kit. He said one year, but I feel it was not an idea familiar to him and he may have been flannelling…

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  13. Owen says:

    This report shows solar as having EROI of 1.6 for Germany

    • gweberbv says:

      It also states an EROI of 4.0 for PV solar. The number you picked is for a-Si cells (after useless buffering), which has a market share of less than 1%.

      • Owen says:

        Buffering only applies to intermittent sources like wind / solar.

        You dont need buffering for a nuclear or coal or gas plant.

        Its just a fact of life that these RES technologies have tiny, or more accurately zero capacity credit. So you need to keep all the existing plant running behind them.

    • Stuart Brown says:

      Pro nuclear as I am, it still pays to look at the credentials of the authors. Institut fur Festkorper-Kernphysik holds the patent for a novel molten salt reactor, which might be a clue – all the authors appear to work there. I think it was a bit naughty not to include buffering for nuclear plants, for example, and I suspect the decommissioning demand at a quarter of the construction demand is too light.

      However, I’m not competent to criticize their numbers, and I love their vision of a nuclear future using the DFR!

    • Euan Mearns says:

      Thanks for the link Owen. The numbers here agree pretty well with most of the other numbers I’ve gathered apart from nuclear where other sources are of the order 10 and this source is 75.

      Gunther, why would one not include the energy cost of intermittency? You can’t simply pretend that these costs don’t exist just because the owners of PV don’t actually pay these costs at present.

      • gweberbv says:


        I am the least one to claim that intermittency comes at zero cost. But assuming that each installed MW of wind and solar has to be accompanied by an – also newly installed – storage capacity of ’10 day full load’ (as is done by Weißbach et al.) is just bullshit. Sorry, I cannot find a better word.

        This has nothing to do with the world we are living in. Globally installed Wind plus PV will soon break the TW level and where do you find the associated storage plants? According to the numbers given in this (very instructive blog) even GdV has only slightly more than 1 full load day of storage capacity (270 MWh compared to 11 MW of wind turbines).

        The standard procedure to deal with intermittency is simply to ramp up and down the rest of the power plant fleet. Thus, the only reasonable way to quantify the costs of intermittency is to determine the additional energy that is necessary to for the dispatchable part of the fleet to perform this additional ramping (compared to a situation with dispatchable-only plants). You can now look to Ireland. Or any other country/grid. If it has a large portion of hydro production (that can stopped/reduced for a gew hours or days), costs will be near zero. If it has mainly FF plants designed for baseload operation, costs might be significant. If have no number for that but I guess it is orders of magnitude cheaper (=less energy consuming) than building pumped storage plants with a generation capacity of 1 TW and a storage capacity of 240 TWh. And this would be just for the first TW of wind+PV. Many more to come …

      • Owen says:

        I know a nuclear engineer who is working on plants in France over 40 years old. So it makes sense that nuclear has the best EROI of all energy sources.

  14. GeoffM says:

    What you say here Gweberby is very bizarre, even for you.

    You claim that the need for a 10-day full load is BS. Well, many respected engineers have done their own calculations and the conclusions I have seen range from 1 day to 30 days, so 10 days is likely to be of the correct order. I once spent many weeks calculating this for the UK from what seemed to be the best contemporary 100% renewable scenario based on the assumption that most renewable electricity would come from wind (prominent people on your side have admitted this) and I came up with a minimum of 3.5 TWh (roughly 3.5 days), for the worst case scenario based on historic UK Wind data.
    But the authorities keep moving the goal posts and you can have as many scenarios as you want hence the wide range of conclusions.
    Weather-dependent electricity is already compensated for by mass stored energy (all that fossil fuel in the ground which replaces renewables when their output is reduced is mass stored energy) but you “greenies” ignore this.

    Secondly, you use GdV as your example for what can happen (ie. the low level of storage there). Well, previous articles here illustrate how much diesel is burnt to maintain power supplies there. And that island has a low population density and is relatively mountainous. Is a big city like London in the same boat?

    Thirdly you laud the idea of ramping up and down conventional plants to replace missing renewable generation. You seem to singing from a different song sheet from the rest of the “greenies”, as they want all conventional generation to disappear. And most of them seem to be calling for mass storage, even if they don’t appreciate/admit how much would be needed and how unachievable it would be.

    • gweberbv says:


      if you are more interested in what *greenies* are saying (or what you believe they are saying) than what is happening in reality … well, I hope you have fun with it. Fighting with your windmills.

      Just to wake you up (hopefully): I did not point at GdV as an example for what can happen, I pointed to it as a striking example what IS NOT happening. Nowhere on this planet, even not in the green Disneyland of GdV, wind or PV is accompanied by a newly installed storage capacity of 10 full-load days (please write this sentence 100 times on a black bord and underline each word). GdV has merely 1/10 of this storage capacity. And this is already much more than what the average country will EVER have.

      So, when your very respected engineers are done with calculating how much storage capacity we need for PV to bring us through the winter, the next task I recommend to them is to calculate the weight of a battery for moving my Porsche Cayenne from Paris to Dakar without recharging. After that I will think for some more useless jobs to do. Maybe how much angels fit on the pin of a needle …

      Seriously: Intermittent energy sources like PV and wind are simply not used in the context that is assumed by the ’10 full-load days storage’ trolls. And there is no sign on the horizon that they will ever be used in that stupid context. Nevertheless, global nameplate capacity of PV and wind is approaching 1 TW. So, it seems that these technologies are used in some other context. People who are interested in reality should study this context to determine realistic ERoEI/EROI values.

  15. It doesn't add up... says:

    Come to that, how is the surplus power wasted? Hasn’t it increased fire risk?

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  17. Alex Cannara says:

    In Calif. we burn gas to make up for wind/solar realities. And, we leak gas. We leaked so much at Alison Canyon storage facility, we won’t have enough for peaker gas plants to make up for summer A/C loads. We leaked so much that we wiped out all the past emissions reductions from all Calif. wind/solar ever installed.

    And, our 1annual leakage is about 4x the US record leak at Aliso. Calif. is a gas state, not a ‘green’ state.

    We’re so lucky that Alison didn’t ignite, as happened in San Bruno is 2010. But, our regulators (CPUC, DOGGR…) don’t care.

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