Solar powered self sufficiency at high latitudes is a fantasy

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One of the oddest delusions is the idea that at high latitudes you can run a house, town, city, or country on solar panels coupled with batteries. The idea itself is so daft I often fear I am attacking a straw man to even discuss it. Yet, a reasonable number of people seem to believe this nonsense.

The most popular form of it comes in the following sound bite: “If you covered all of Britain’s roofs in solar panels, it would meet 100% of Britain’s electricity demand”. The claim itself is actually false, even if you simply consider total energy produced – and ignore the long stretch of winter when Britain’s solar panels might as well be disconnected from the grid. And what a glorious coincidence this would be, that covering all available roof space in solar panels would precisely match demand.

This belief in solar self-sufficiency has, unsurprisingly, reasserted itself in the wake of a Silicon Valley superhero (Elon Musk) creating a “game changing”/”disruptive”/”expensive toy for rich people” battery that can store electricity during the day from your solar panels. This, some hope, will let people disconnect from the grid. Here is how a BBC journalist recently finished a piece on “The town where one in ten have opted for solar power”:

However, moves to produce batteries to store home-produced energy could further revolutionise the economics of solar power. Should they prove effective, the town of Wadebridge would not only be self-sufficient in energy, but it could become a net exporter too. A British town exporting sunlight? Now you’ve heard it all.

Solar self sufficiency, or grid disconnection may be an option if you live in California – or maybe not, just think of getting through Christmas with a cloudy sky and nothing but solar panels and batteries to power the various activities. It will not be an option in Britain, or any other high latitude country.

The problem is rather straightforward: Winter. Britain’s electricity demand peaks at more less the exact same time as solar panels are producing minimal electricity. Let me reproduce below an old figure I created for Germany. In Germany, just over 5% of electricity demand is met by solar panels on average. However, on the worst days this can hit as low as 0.1%. For Germany to meet its year round demand from solar panels it will need something on the order of 1000 times more solar capacity than it currently has.

That’s if we assume they point put in place enough storage to store something like half a day’s worth of electricity demand, which is not an easy task. Alternatively, they could build less solar, but build enough storage to store a few weeks worth of electricity demand for winter. I could quantify why this is improbable, but that might be labouring the point. PVhighlow

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13 thoughts on “Solar powered self sufficiency at high latitudes is a fantasy

    Edna Semtex said:
    May 24, 2015 at 10:57 am

    The mystery of why the UK as a small island doesn’t embrace tidal power more readily is doubly troubling when it comes to Cornwall. When it comes to Wadebridge, they have to do something since a third of households are in fuel poverty – eating vs heating, and the renewable energy network places most emphasis on energy efficiency, although they will install solar panels for free so they can keep the feed in tariff.

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    johnrussell40 said:
    May 24, 2015 at 12:05 pm

    I’m in the SW and the recorded total for Dec/Jan from my 4kW array (the largest permitted for the FIT) was 239kWh. That averages out at 3.85kWh per day.

    Last June/July I recorded a total of 1,012kWh, which is 16.59kWh/day on average. I reckon the new Tesla storage system, as advertised, would possibly enable me to go off grid (I’m all electric) for about 4 months of the year: the 4 months when I require no heating. Even that would be pushing it as we often get stretches of 3-4 days of cloudy weather as a low comes in.

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    guynewey said:
    May 25, 2015 at 6:14 am

    Surely the important discussion here is not whether we can be ‘solar self-sufficient’ but what contribution solar can make and at what cost? If (and I know we are a long way from this) solar was dirt cheap, as were batteries, what would the problem with them making a contribution for a period of the year?

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      Robert Wilson said:
      May 25, 2015 at 11:08 am

      Guy

      I’m very skeptical that solar can make anything beyond a marginal, ie 5-10% contribution to a decarbonisation grid.
      In the medium term it will be limited to around 5% due to grid frequency issues. At least that is the view of National Grid.

      In the long run it will be limited by the simple reality that electricity demand peaks in winter and solar peaks in summer. This problem will likely get worse with electric heating.

      My guess is that solar would more or less be redundant in a decarbonised British grid. You can see this if you look at decarbonisation scenarios by the CCC and then try adding solar on top. You just end up with most of the solar being curtailed in summer if you push it much above a few percent.

      Maybe I’ll blog on this in future. But I might have to do it for Germany or France who have output data for solar. Though this might be more suitable for an academic paper than a blog post. I’ll see.

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    peter2108 said:
    May 25, 2015 at 9:00 am

    Barratr’s are building a small 50+ estate near where I live in Wakefield. The expensive houses have solar panels (the cheaper ones do not). Panels are going mainstream.

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      Robert Wilson said:
      May 25, 2015 at 10:22 am

      Barratt houses, solar panels or not, are a bigger blot on the landscape than wind farms.

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    Jamie said:
    May 25, 2015 at 6:30 pm

    It’s eminently feasible for individual homes to go off grid with solar PV and batteries at UK latitudes. A south facing 4kWp installation in the Midlands will generate an average of 4kWh per day in December (according to PVGIS) so if you can get your daily demand under that and have a reasonably sized battery to deal with extended periods of gloom then it’s doable.

    4kWh per day is under 1,500kWh per year which is about half what the average non-electrically heated home in the UK consumes today. Kit out your home with high efficiency appliances and replace your lights with LEDs and you could easily get demand down below 1,500kWh. Of course as soon as you throw electric space heating / hot water / cooking into the equation then that falls apart but more than 80% of UK homes are heated by gas.

    So it’s certainly technologically feasible at a household level, but as long as we have easy access to grid electricity there is no need to go completely off grid so it’s going to remain a niche technology for a while yet. As electricity supplies tighten, fuel prices go up, renewable penetration increases etc I expect that being able to drop off the grid for a period using battery storage will become a more attractive option for many people with PV on their roofs.

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      Robert Wilson said:
      May 25, 2015 at 7:08 pm

      Nonsense

      How much money do you think the average family has? Can people really afford to pay 4, 5, 10 times more for their electricity for the non-existent benefits of going off-grid?

      Eminently feasible? Perhaps in an alternative universe where everyone is a member of the 1%.

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        Jamie said:
        May 25, 2015 at 7:45 pm

        Why nonsense? You state in your post that “One of the oddest delusions is the idea that at high latitudes you can run a house, town, city, or country on solar panels coupled with batteries.” I was pointing out that it’s technologically feasible for a house to go off grid on solar at UK latitudes and it doesn’t require massive PV arrays or massive battery banks. I didn’t say that it’s going to happen on a large scale, in fact I said that it will remain niche for a while yet so of course I’m not suggesting that average UK families are about to adopt this measure en masse.

        However the price of electricity is not going to remain at its current levels and batteries and solar are going to continue to get cheaper and I fully expect it will come within reach of more affluent households and potentially in the future within the reach of a much larger proportion of the population. But it’s only possible with substantially reduced demand.

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        Robert Wilson said:
        May 25, 2015 at 7:53 pm

        So, let me get this straight. Individuals should drastically reduce their electricity demand so that they can go off grid. The result will be that their solar panels will produce more electricity year round (on average) than their previous demand. But the benefit, of paying for all this, is that solar panels can provide the juice at 8pm on Christmas Day?

        How bizarre.

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      donoughshanahan said:
      May 27, 2015 at 8:24 am

      Jamie

      The current cost of a 4 kWp roof solar installation in the UK is around £6,000. There is a generation FiT and an export FiT; 14.38p/kWh and 4.77p/kWh respectively according to Ofgem. 1 kWh of exported electricity is worth ~19p.
      Mosts houses are assumed to export 50%. A in the south of England has a 0.1 capacity factor and the price of mains electricity is set at 0.11p/kW. NREL suggests 0.5% degradation in performance/year. Interest/time value of money, maintenance etc are not taken into account.

      Using this baseline , the payback is just over 9 years with a total revenue generation of £14,884. For example in year 1 a total of £780 is saved.

      Changing various numbers (etc)
      · Decreasing the cost to £3,000 still requires a 5 year payback.
      · Exporting all of the electricity (so both FiT’s applied) yields a 7 year payback.

      If only the export FiT was maintained, the price of the system would have to drop to £5,271 to payback in 20 years, ~£2,700 to payback after 10 years and ~£1,300 for 5 years.

      Financially it might make sense but environmentally, it is a very expensive way of reducing carbon.

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    Jamie said:
    May 25, 2015 at 8:14 pm

    No. I am simply saying that if individuals wish to go off grid at UK latitudes then it is perfectly feasible but they need to reduce their demand first. This is very well understood by anyone who’s explored off grid living. I’m not saying it’s cheap, I’m not saying it’s going to be widespread any time soon, I’m just saying it’s technologically feasible and it doesn’t require a huge PV array or a huge battery bank (or even the sacrifice of any comforts, just lower demand through more efficient energy using products).

    But all this is beside the point because the main idea behind domestic scale batteries is not to go fully off grid but to take customers off grid at peak times and provide grid balancing services at other times (i.e. to soak up excess renewable generation at times of low demand). Again, much lower demand is very desirable because it means that you can take yourself off grid using a smaller battery.

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      Robert Wilson said:
      May 25, 2015 at 8:25 pm

      But what is the actual benefit? I’m perplexed. You reduce your demand so that you can run a house on solar panels. But this will certainly cost you more than meeting your original demand from the grid. What’s the benefit exactly?

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