UK Solar PV Vital Statistics

UK solar PV installation companies have been in the news for the wrong reasons. The reduction in subsidies has seen a number of companies go bust. Should we be bothered by this? Regular readers will be familiar with my opposition to installing solar PV panels on north facing roofs in a land where the sun seldom shines for 3 months of the year.

The UK National Grid publishes model data for solar production in the UK so we can get an idea how much electricity all those roof mounted panels produce. The model data are published with 30 minute resolution and I have chosen to graph all the data for 2014, the most recent year with full cover. The idea is to try and show graphically how useful solar PV is in a high latitude country like the UK.

A good starting point is to look at the contribution solar PV made to UK production in January 2014 (Figure 1).

Figure 1 According to The Renewable Energy Foundation (REF), the UK had about 2700 MW installed PV capacity in January 2014. And according to National Grid, this produced 54 MWh of electricity, equivalent to 0.19% of total UK demand. The small, barely visible, blips along the x-axis is the solar PV output. The load factor was 2.7%. Click all charts for a larger and readable version.

I wanted to chart all the solar data for 2014 to show how the output varies across the annual cycle of seasons. This is quite a charting challenge. I have plotted individual charts for each month and grouped them into threes below (Figures 2 to 5).

Figures 2 to 5 Working from top to bottom, installed PV capacity increased from 2691 MW at the beginning of January to 5131 MW at the end of December. The charts clearly show, as is to be expected, PV output increases in Summer and declines in Winter. There is substantial variability within any given month reflecting changes in cloud cover. In winter months, this cloud variation is up to a factor of 8. In summer months, the peaks are also much broader reflecting the longer days (Figure 6).

Figure 6 January and July 2014 compared. The January output has been grossed up by a factor 0f 1.45 to reflect the growth in installed capacity between January and July. The summer peaks are taller, more regular and broader. The January and July peaks are also offset by 1 hour, January operating on Greenwich Mean Time (GMT) and July operating on British Summer Time (BST). Peak winter demand is always around 6 pm. At that time in January, UK solar PV production is always zero since The Sun has already set. In mid-Summer, PV output is less than half the midday peak come 6 pm.

Generation varies in proportion to the amount of sunlight that is in turn controlled by the length of day, the height of The Sun above the horizon and the amount of cloud cover. In the winter months, all of these factors work against solar PV in the UK, hence winter generation is a fraction of summer generation. Correcting for the growth in installed capacity, July PV generation was 8 times higher than January generation in 2014.

The monthly vital statistics are summarised in the Table below. Capacity has been increased linearly from 2691 MW in January to 5131 MW in December. Capacity factor varies from a low of 2.44% in December to a high of 20.45% in July (Figure 7).

Table 1 Summary of generation statistics from National Grid. Installed capacity from REF. The National Grid generation data combined with the REF installed capacity data yields a solar PV load factor of 10.3% for the whole year. This compares with 10.8% published by DECC and 11.8% determined from REF data (see A Note on UK Renewable Load Factors) and with 10.1% estimated by Roger Andrews.

Figure 7 Seasonal variation in UK solar PV load factors plotted from Table 1. UK power demand is highest in winter and lowest in summer, negatively correlated with the above.

Quite often the sustainable renewables solution to inadequacy is to over dimension the infrastructure. In January 2014 there was 2.7 GW of installed capacity that produced 0.19% of power demand (Figure1). Let us imagine this was increased by a factor of 10. This would mean 27 GW of installed capacity – enough to cover 50% of UK demand at 100% load, but it would still provide just 1.9% of gross UK demand in January and 0% of peak demand.

It is this latter point that is important. The 6 pm maximum demand peak in winter months sets the capacity requirement for dispatchable UK generation (Figure 1). If solar could be relied upon to always provide some power at 6 pm in winter this would reduce the required capacity of conventional generators and replacing one with the other may have made some sense. But solar PV will never ever produce a Watt of power at 6 pm GMT in the UK in the winter months meaning that 100% backup will always be required.

One final consideration is the ERoEI for solar PV. Prieto and Hall have estimated, somewhat controversially, that solar PV in Spain has ERoEI of 2.5 and Spain is a sunny country. The load factor in Spain is estimated to be 18% compared with 10% in the UK. Adjusting ERoEI for load (10/18*2.5) ERoEI for solar PV in the UK would be of the order 1.4. Solar panels are made using fossil fuels. The CO2 from the manufacturing process is in the atmosphere today and it may take 15 to 20 years for the panels to offset this CO2 that has already been produced.

Concluding Thoughts

Low CO2 electricity for free sounds like a great idea and too good to be true. It is. There are undoubtedly niche applications for solar PV. The Space Station for one, although notably the Mars rover is powered by nuclear. Hobby Greens wanting to indulge their fantasy living off grid surrounded by a stack of toxic lead acid batteries, pretending to save the planet are welcome to do so, so long as they pay the costs themselves and do not expect everyone else join their delusional path.

There may be other niche applications for solar PV in developing, sunny, African countries where it may provide valuable electricity to power the local cell phone network or communal computer. And there may be grid scale applications in sunny lands, but if Prieto and Hall are correct, this too is questionable.

Deploying and subsidising grid-scale PV in the UK appears to be plain stupid, especially in a country like Scotland where it is doubtful that PV panels will ever repay the energy used to create them. They are likely making the problems they are designed to solve, worse.


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41 Responses to UK Solar PV Vital Statistics

  1. Joe Public says:

    Another very interesting posting, Euan. Thanks.

  2. I very much agree with your position on this issue Euan. If solar makes any sense at all, it would only be in the tropical regions of the world, and even there it’s marginal. A friend of mine was recently in the remote jungles of Papua New Guinea, and some off-grid villages were using solar panels to charge up flashlight batteries and to power radios – I would say that’s a practical use of solar. But trying to run a developed country’s factories and server farms off of solar is just an expensive feel-good project, to show how “green” we are. Unfortunately, public opinion is being herded towards “alternative energy” which is indeed just for show.

  3. Euan: You mention niche applications for solar in places like Africa. I can think of one in Scotland.

    The island of Eigg ran out of renewable energy during an extended fine spell in the summer of 2010 when the wind stopped blowing and the hydro reservoir dried up. A few more PV panels combined with the island’s 220kWh of battery storage would have kept the RE coming, and the added cost of installing them would have been negligible relative to the system’s £1,664,828 total cost. The panels would of course been of no use during the winter but I’m told that lack of wind and rain isn’t usually a problem in Scotland at that time of year.

    • Euan Mearns says:

      but I’m told that lack of wind and rain isn’t usually a problem in Scotland at that time of year

      We have an interesting weather pattern that has been established for weeks now with high pressure dominating over the UK and northern Europe. Post on this coming up – “Dead Calm”.

      Its been fantastic weather for the time of year, but wind production has often been below 1 GW. This may be linked to cool N Atlantic (the AMO shifting) or to el Nino?

      • Roger Andrews says:

        If I knew the answer to that I would be selling weather forecasts for big bucks instead of writing posts for free on this here blog 😉

  4. Frederick Colbourne says:

    Thanks for this. I have been following you blog for some time but did not delve into the calculations.

    I found the Digest of UK Energy Statistics (DUKES) easier to use. The site actually provides Excel spreadsheets.

    Dukes gives Solar photovoltaics installed capacity as 5,377 MW which seems to be based on the end of year capacity and not as accurate as with monthly figures in Table 1 above. DUKES potential maximum potential energy would therefore be 47,138 GWh for 2014 compared with actual energy produced of 4,050 GWh.

    The DUKES figures give a “load factor” of 8.6% average for the year compared to 10.2% if the average installed capacity from Table 1 is used.

    (See technical notes below for an explanation of the quotation marks around “load factor”.)

    Whichever way the calculation is performed, the load factor for solar is low compared to onshore wind (25%) offshore wind (34%) and bio-energy (57%). (Based on the DUKES data.)

    However, efficiency as measured by “load factor” is only one input to the policy assessment. What needs to be considered also is the cost per kilowatt hour of the output because it is the output that is sold to consumers. That cost includes capital costs together with operating cost.

    I referred back to your post:
    and found that in a comment EDMH provided the capital costs of various generating technologies as follows, “…the overall capital cost of all European Renewable Energy installations averages out at about €27billion / Gigawatt, whereas the cost of a conventional gas-fired generation is about €1 billion / Gigawatt.

    That overall value for Renewables at €29 billion / Gigawatt is derived from the combination of
    Onshore Windpower €14.2 billion/GW
    Offshore Windpower €41.4 billion/GW
    On Grid Solar Power €48.5 billion/GW”

    The U.S. Energy Information Administration (EIA) figures show that gas-fired power plants reach power factors of around 50%.

    The conclusion: Solar capacity costs 48.5 times as much to install as gas capacity with only around 20% of the efficiency of a gas-fired power plants.

    To be sure, the gas to fire a gas power plant costs money, but there is no way that savings in operating costs (sunshine compared to gas) can overcome the twin disadvantages of UK solar: high capital cost and low efficiency.

    Technical notes on terminology: In the US, the net “capacity factor” of a power plant is the ratio of its actual output over a period of time, to its potential output if it were possible for it to operate at full nameplate capacity continuously over the same period of time. This is the “load factor” as used in this blog.

    In the US the term “load factor” is reserved to describe the average load divided by the peak load in a specified time period. Load factor is the ratio of average load divided by peak load.

    The difference in terminology may be that the US definition of “load factor” is based on engineering and the UK definition is based on business practices.

    • Euan Mearns says:

      Thanks for clarification of “load” and “capacity” factors. To be clear I have used these interchangeably and call it a factor even though I convert to % 🙁 My terminology is based on actual generation / maximum possible generation in a given time period. Solar is immediately disadvantaged since over an annual cycle the max possible capacity factor is about 50%, since it is on average dark for 50% of the time. And I’m unsure how the outputs are rated. This is probably maximum possible generation with optimum conditions that will be only momentarily reached in any location. That’s one for Clive Best to calculate.

      Many years ago Nate Hagens and Hannes Kunz had a series of posts on The Oil Drum on renewables called “The Fake Fire Brigade”. One of the points they made was that our current economic system of paying rent on borrowed money made high CAPEX renewables uncompetitive. And while avoiding having to pay for Nat Gas may seem like a great idea, I’ve also been surprised to learn that fuel cost is a relatively low portion of the overall cost of electricity. In Germany, the retail cost is split roughly equally between 1) generation, 2) grid and 3) tax. And so the price of gas is a fraction of one third. In calculating the cost / price of solar, the grid costs and system balancing costs are all conveniently forgotten. And of course tax is negative in the form of subsidy.

  5. Jack Ponton says:

    In the right places solar is sensible and cost effective. The right places are +/-20 degrees of the equator where there is much less seasonal variation. Since this area is largely the developing world without well established grids the distributed and variable scale nature of solar is an advantage. It is also likely to displace truly health and environment damaging technologies such
    as kerosene lamps and diesel generators.

    Unlike wind, which is a mature technology whose costs and efficiency are unlikely to improve much, solar is still developing. The best solar panels have an efficiency of only 20% and there are lots of bright ideas around for increasing efficiency and reducing costs.

    There is also a techically feasibly solution to overnight storage, which is all that would be needed in the tropics. Current Li-ion batteries can do this, albeit at a price that is still rather high for developing countries (the Tesla Powerwall costa $3k a throw) but this again can be brought down. By contrast there is no plausible technical solution to the week long storage required to offset wind intermittency, let alone summ-winter storage for northern solar.

    It is really shameful that the UK government subsidises rich consumers to put solar panels on their roof, when the same money spent on deploying solar in Africa and Asia would not only reduce much more CO2 emissions but would improve peoples’ lives and health. A good move for the UK would be to remove responsibility for climate change from the Energy ministry and move it to Overseas Development.

    • Euan Mearns says:

      I agree with most of this apart from the elements of cost and maintenance. Using wood for cooking causes great health problems in many parts of the developing world.

      India is perhaps a good example to use. It has a well developed grid running mainly on coal. Someone can perhaps post a cost comparison for coal versus PV + battery storage. One problem is always going to be CAPEX. Many Indians I imagine can afford to buy a little electricity (subsidised?) every month. Very few will be able to afford a PV system + battery storage.

      The UK energy policy is currently in a strange place where actions no longer match the words. The Guardian article I link to up top says that subsidies for solar are to be cut by 87% which if true will kill the industry stone dead. And subsidies for on-shore wind have also been cut. But government rhetoric on renewables, CO2 and climate change has not perceptibly changed.

    • jacobress says:

      “In the right places solar is sensible and cost effective.”
      We are hearing this refrain continuously, but repetition does not convince.
      Could you please give an example of those “right places” with numbers showing how solar panels are “cost effective”?
      They are “cost effective” only in an isolated place where there is no grid, provided they were given as a present (at no cost) by Greenpeace activists.

      • Leo Smith says:

        The right place is a planet with no clouds that always presents one face to the sun

        There is another place rumoured to exist, called ‘cloud cuckoo land’ though even there the presence of clouds casts doubt – or possibly shade – on the efficacy…

  6. Tim Churchill says:

    “Deploying and subsidising grid-scale PV in the UK appears to be plane stupid”

    Heh heh, they fly planes powered by them too. No doubt you have an overactive spell checker.

  7. yoananda says:

    Very interesting and accurate !

    I think solar MUST be associated with it’s usage. We must think in terms of exergy and not energy like we used to.

    This means energy production CANNOT be dissociated from it’s usage. PV is not meant to heat us, is not meant to be used in industry. It can be used for informatics, for DIY, maybe for some transport (we use more cars in the day, and less in winter … so it can fit more), etc…

    And we must think of all energies in these terms : exergy.

    • A C Osborn says:

      It is really great at charging Computer, Phone and Game console batteries.
      It is also good at “trickle charging” Car Batteries which are statinoary for long periods.

  8. roberthargraves says:

    Yet another good post. How do you and Andrews find the time!? Can you present in Paris? You inspired me to repost a couple of Tom Murphy posts on my Facebook page.

  9. Ingrid Strawson says:

    Another great analysis and very interesting for those of us who have PV panels installed. However, I feel there is one point which you have not addressed – batteries! I was disappointed to find that the UK government subsidy / feed in tariff did not include solar systems which included batteries to store the electricity. I have been involved in a solar project in a hospital in The Gambia, which at the time was off grid. The batteries to store the electricity generated by the panels are a fundamental part of the system providing light for the hospital, refrigeration and pumping water 24/7. I believe all new builds in the south of the UK should include solar panels covering south facing roofs and as soon as possible these should be supported by batteries. Micro systems have the potential to make us more resilient. Peak demand is an interesting challenge – a shame we don’t have sufficient HEP to address our needs in the UK.

    • Euan Mearns says:

      Roger did a post on battery requirements:

      Rooftop solar system at latitude 60 north

      Figure 5 plots the data. To meet winter demand at this latitude the batteries have to store 1,522 kWh of surplus summer generation, requiring 153 Tesla 10kWh wall units costing $535,500 and weighing 15.3 tons:

      So at UK latitude it boils down to scale and cost. Even covering the diurnal cycle in winter would be pointless since generation is so low in any case. An off-grid hospital in The Gambia is a different proposition.

    • jacobress says:

      “I have been involved in a solar project in a hospital in The Gambia, which at the time was off grid.”
      I guess it would have been cheaper to just install an generator (diesel or gas). It would have also provided power 24/7

    • A C Osborn says:

      Why the hell do you want to make “New Builds” even more expensive than they already are.
      It is bad enough that the EU/Government is now forcing “sprinklers” on new builds without having to have Solar as well.
      Young people can’t afford to get on the property ladder now, don’t make it even worse.

  10. climanrecon says:

    My rough rule of thumb is that solar can power your lights and radios, if you use it to recharge a battery. A simple scaling law applies, a tiny solar panel on my watch can generate enough power for it, likewise a panel on a shed can light that space for several hours, and roof sized panels on a house can cope with several lights and radios.

    The problem for solar is that everything it can do can be done much cheaper just by recharging batteries from the mains, so only makes any sense for off-grid applications, or for harvesting govt subsidies.

    Sorry, but I can’t shed many tears for UK solar businesses going bust, the workforce consists mainly of electricians, roofers and scaffolders, all of whom can find work elsewhere.

  11. Rob says:

    Does anyone know what use solar power is to the UK grid ?

  12. ducdorleans says:

    atm, here in Belgium, there’s some controversy about the cost of renewables, that has been, one way or the other, “forgotten” to be included in the price of electricity …

    nobody knows – or he, or she, who knows doesn’t really want to tell us – what the total sum of subsidies, and feed-in tariffs, and whatever candy they got, amounts up to …

    this morning on the radio, I heard one politician try the sum of “7 billion euros” … (vs our 440B€ GDP)

    all that resulted in some rather major price hikes … which still have to show up in all the citizen’s bills …

    anyway, to know what we really got for all those investments in renewables, I got and plotted some data for a recent 5 day period … I have to admit: little wind (there was some CO alarm …), and misty to grey …

    if anyone is interested, some graphics and an xlsx are here …

  13. Luciano Bacco says:

    So in Italy : Italy installed up to 1.38 GW of PV capacity in 2014

    Italy added approximately 1,389 MW of new PV systems in 2014, according to Italian consultancy Elemens, which cites a statement from the president of the renewable energy association Coordinamento FREE, Giovanni Battista Zorzoli. Zorzoli, which could not rely on official statistics to calculate the capacity increase, said it was able to determine how much PV capacity was installed in 2014 by studying electricity generation figures for 2013 and 2014 published by Italian TSO Terna SpA. Elemens notes that production from PV sources increased from 21,228 GWh in 2013 to 23,229 GW in 2014. This increase, combined with weather data for the past 2 years, led the company to the conclusion that Italy had a cumulative installed PV capacity of 19.11 GW at the end of 2014. If correct, this means Italy added about 1.38 GW of PV capacity last year. In 2013, the country added approximately 2 GW of new PV capacity. With 579,524 PV systems connected to the grid, Italy reached a cumulative installed PV capacity of 18.42 GW at the end of 2013, according to the Terna. The country had 16.41 GW of installed PV power at the end of 2012. Under the five Conto Energia incentive programs, Italian energy agency GSE granted incentives to 550,074 PV projects with a total power of 17.62 GW. © PHOTON

  14. During the darkest longest nights of UK winters, the Tropic of Capricorn experiences the sunniest longest days.

    So I might suggest grid scale photovoltaic arrays sited somewhere along the Tropic of Capricorn

    Pick your PV array site – Namibia looks convenient and scores highly in the Atlas of Solar Power.

    Then a High Voltage Direct Current electrical power transmission line delivering perhaps as much as 50% of power back to Britain may be possible.

    • Graeme No.3 says:

      Why use solar panels? Cut out the inefficiency and can the sunlight directly. Considering the gain in efficiency all that is needed is chicken feed, a billion or two – pay some into my bank account in Nigeria and I will send you details.

    • jacobress says:

      How is that as “energy security” ? Having an important part of your power produced in Namibia?
      Or the crazy idea of the “Desertec” consortium – of producing Europe’s power in Marroco and Algeria?

    • Leo Smith says:

      Your tongue is sticking out a bit too far this time.

  15. jacobress says:

    For the solar power addicted – solar panels always make sense “somewhere”. Not here, not now, but somewhere, in some remote country, under special (fictional) circumstances (off grid).

    No one ever installed one solar panel, anywhere, because “it makes sense”. All solar panels were installed only, and exclusively for the purpose of harvesting subsidies. In remote, off grid locations – if you need electricity you install a (gas or diesel) generator.

    There are probably some exceptions – rich people, ideologically motivated, who have more money than brains. For them cost or efficiency don’t matter, only the satisfaction of feeling virtuous, which they can well afford.

    • Jacobress, that’s not really true, sorry! I have a 24 foot power cruiser, with a composting toilet and a nominal 86 watt solar panel with a large deep cycle battery. This provides enough juice to run a small fan 24/7 (actually a computer ventilation fan) for the toilet, led lights, the anchor light, a radio, and one of the instruments. The whole setup is now ten years old, and has been faultless.
      I am not an eco-loon, and don’t believe that carbon dioxide is a climate control knob, but let’s give credit when it is deserved. There is nothing more off grid than a boat.

      Regards, Tony.

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