The solar exponential

In his regular email, Peter Diamandis writes,

Currently, the amount of solar installed each year increases by 35 to 40 percent.

…One megawatt of solar power is estimated to require 8 acres of land. U.S. solar capacity is on the order of 3,000 megawatts (only 0.65 percent of U.S. power produced)

Total electricity demand in the U.S. has been flat in recent years. So let’s play with a 40 percent rate of increase starting from a low base of 0.65 percent of U.S. power production. At that rate, it will take about 7-1/2 years for solar to account for 10 percent of U.S. power production. But then in another 7-1/2 years, it would be 100 percent.

Of course, the solar exponential might not be that high. Still, it is an interesting illustration of the potential of compound growth.

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16 Responses to The solar exponential

  1. John says:

    The problem in some areas of the UK is that power companies do not have sufficient cable capacity in the network to take solar power. This is particularly so in the south west where insolation is the highest.

    A possible engineering solution for big solar farms may be flow batteries to absorb the power in daylight hours and release it in the evening when domestic demand is at its highest.

  2. Michael L says:

    Solar+battery is becoming cheap enough that it has made it worth it for utilities to start switching over. Utilities are discovering that batteries are the best solution for regular operations as they can respond immediately and can assist in frequency regulation. The change is coming and it’s going to start coming fast. In about 7-10 years there will be a high rate of change as it becomes so cheap that it’s the right thing to do for many utilities financially.

  3. Steve Carson says:

    The real problem.. requires understanding how the grid operates and the cost of storage. Imagine the situation as we move towards 100% of the population with solar. At midday there is so much energy it is higher than demand. Hurray -or not, as grid operators will tell you. From 3pm to 9am there is little or no power.

    At this point let’s assume we have cheap storage, for example, a battery with a photo of Lord Musk on the side. All problems are solved and anyone suggesting otherwise is a “denier”.

    The UK had a recent report on how to implement their policy of 80% reduction in emissions by 2050 – and in the boring tables they had estimated the cost of batteries in 2040-2050. A 2-day hiatus in wind power (not much solar in the UK) would require batteries that cost 10% of GDP every year. So it’s the cost of the NHS (National Health Service).

    It gives you an idea of the problem. Either a new battery technology is needed. Or solar expansion has serious limits.

    The real alternative is wind + solar + flexible (peaker) gas plants as backup + lots of high capacity (expensive) transmission lines.

  4. T Boyle says:

    How big is 3.7 million acres?

    It’s quite a bit – a bit bigger than the land area of Connecticut. And, of course, allowing for the fact that solar doesn’t produce at 100% all the time, we’d need to double or triple it, which would be somewhat bigger than Vermont.

  5. edgar says:

    The U.S. Energy Information Administration certainly does not predict 40% compound growth for renewable electrical power (including solar) but rather sees about 2% growth from 2017 to 2050, roughly doubling the total produced from about 625 to 1241 BkWh annually. This against total electrical power production projected to grow from 3,843 to 4,543 BkWh per year over the same period. Renewables may be the fastest growing electricity generating source and may eventually get bigger than coal, but absent disruptive change, will likely only be a part of the story, not the whole thing.

  6. baconbacon says:

    Large(r) scale adoption in new tech doesn’t imply exponential growth, it often implies the end of exponential growth. Imagine that you had a million dollars in capital and were looking for a long term investment. You could start a solar power plant now or you could invest in T-bills for a few years and then start a solar plant with the newer technology. If you believe there will be large leaps in efficiency in solar during those years then the latter is more profitable, and if not the former is. Large increases in use for a tech like solar (that is producing a good that has plenty of production from other sources) indicates an expectation of lower efficiency gains in the near term than were experienced/expected in the recent past.

    Subsidies and their expiration dates also probably play a significant role here.

    • Hopaulius says:

      Illustrating your point, I live in a rural small town in a sparsely-populated county in western Washington state. Yesterday I inquired about putting solar panels on my roof. I learned that the local power company does not have the metering capacity to install ANY two-way meters. Thus household-level batteries are required, spiking the cost out of reach.
      Second, the county recently imposed a moratorium on cryptocurrency mining. The application requested 10 Megawatt capacity, and the county currently uses a total of 80 Megawatts. In my town the only remaining coal-fired power plant in the state has been required by state law to shut down by 2025, and the capacity will likely be replaced by natural gas. Windmills mar many formerly pristine views in the eastern part of the state, yet the coal plant was ordered closed in part due to the allegation that it produced smog that obscured views of Mt. Rainier. My eyes tell me that this claim is idiotic. But bird-chopping windmills everywhere you look, go for it!

  7. Jeremy, Alabama says:

    It’s an interesting illustration of the presence of frictions in compound growth. Sooner or later you run out of land, or rooftops, or other limiting factor. There is no chance that growth of solar will remain on a compounding schedule beyond 10% or even so far.

  8. Matt H says:

    The problem with renewables plus batteries isn’t short term time shifting. It’s seasonal storage. If you have solar or wind and batteries to spread out the release of energy to the grid to 24 hours a day, it seems like a full solution, but it’s not. You need to be able to handle low wind for a week, or a volcano that lowers solar power production over a few weeks. You can get more reliability out of the system by having geographic and generation diversity, but if want a system as reliable as current one, you need a long term storage option. Current technology to do this just isn’t there, lithium batteries aren’t designed to shift power consumption over months.

    This actually might not be too hard a problem to solve, just one we haven’t spent time solving. We’ve invested lots of time to making batteries in our phones and laptops better. This led directly to electric cars becoming a real market. If we can focus our attention on the right problem renewables can work.

  9. Matthew Young says:

    Solar direct electric vs solar artificial liquid fuel vs solar fossil fuel.

    Solar + atmospheric co2 = artificial liquid wins, in my opinion. Liquid fuels delivery and storage beats electrical every time. Liquid hydro carbon fuel has a much cheaper storage, a tank. That vs the piles of lithium everywhere/ Liquid fuels have at least an order magnitude increase in energy density than battery.Getting liquid fuel from the atmosphere requires about four times the land and four times the capital equipment. But everything else remains the same, the fuel is carbon neutral in flow. So the balance is four times the fixed cost vs piles of lithium everywhere.

  10. George says:

    It doesn’t matter which power source you like….people aren’t thinking:

    You can grow processor speeds, and electronic capability at 40% a year. You can do other technological growth.

    You can grow companies from startup at that speed. For a while.

    But to grow solar that much, you need investment capital. Solar costs at least as much as any other power source per installed KW capability. It already took billions to get to 0.65%. You have an already installed base of power plants that were built with an aggregate investment in the trillions. Many of them are not paid off – you can’t just shut them down without paying off the loans, and paying hundreds of billions in decommissioning costs. After that you have to pay to build all that solar capacity.

    You can’t grow investment capital that fast. You are hypothesizing several trillion dollars in the next 7 1/2 years….and then 10 times as much in the subsequent 7 1/2 years.

    What part of the economy are you planning to devastate in order to scrape that much money together?

  11. Brandon Berg says:

    I don’t think exponential growth can be sustained here, because there’s no positive feedback mechanism. Doubling the number of installed solar panels doesn’t double our capacity for manufacturing and installing solar panels.

    If we collectively installed 5 square miles of solar panels last year, maybe it’s not that big a deal to do 7 this year. But we’re talking about manufacturing and installing hundreds of square miles of solar panels per year in the final years of this 15-year schedule, which doesn’t seem feasible.

    Exponential growth works best when there’s a positive feedback mechanism that allows your current stock to increase the flow rate, and I just don’t see that here.

    • John says:

      Surely one positive feedback mechanism is the fact the energy prices from grid networks are subjected to continued and high inflation, whereas solar panels and related products are subject to deflation.

      One downside is the fact that grid networks are authority biased, and authorities can stem the flow by imposing tax penalties on people who use renewable energy. Admittedly most authorities have tried to encourage renewable energy up to now, but there are some signs that this may be changing. People in power usually have a term of office that is short compared to timescales of global climate change, so their personal interests do not coincide with those of the human race as a whole.

    • Jay says:

      Nothing in real life keeps going exponentially. Exponential growth is always the start of a sigmoidal curve; the biggest question is hardly ever how fast something will grow but how much it can grow before it levels out.

      As I’ve said before, if you put a grain of rice on a chessboard and double every square, what really happens is that you run out of rice (or chessboard space, or patience, or time, etc.).

  12. collin says:

    Well, I seem to remember that many of world’s failure was too much faith in exponential functions. (How about the housing price increases in 2003 as an example!)

    1) Solar has several roadblocks in huge growth in a few years. It is booming in California where we like $.30 kwh at certain usage threshold so solar does save money here that would not save in Texas or other areas of the nation. (Remember consumer make choices on their purchase price not on production price.)
    2) It is hard for solar to live off the grid. However it does have a support of the Goldwater types in our area because they love living off the electric company grid and prices.

    Long term, this does not look good for coal and natural gas as:
    1) Electric cars are still 10 years away.
    2) Electric use is not going up significantly any time soon.
    3) Wind and solar costs continue to drop.

    That said, what are your thoughts on the coming First Energy bankruptcy. Obviously we can’t close all theirs plants the next several years but some will need to be closed.

  13. Matt says:

    “U.S. solar capacity is on the order of 3,000 megawatts”

    How is this measured? What flat surfaces are taken into account? Roofs of houses and buildings? Can you stack and layer solar panels? If so, is that taken into consideration. I tend to get skeptical when people use simple arithmetic to make large predictions while taking into account no other factors.

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