31 May 2013

The plummeting cost of solar energy - updated

The total amount of energy we use every year – from coal, oil, natural gas, hydro, nuclear, and everything else – is dwarfed by the amount of solar energy hitting the planet each year. How dwarfed? The solar input is 5,000 times greater than the amount we use from all those sources, combined.

In fact, it would take only about 0.3% of the Earth’s land area to meet all of humanity’s energy needs through 2030 via solar power.
That's the most encouraging graph I've seen all year.  Via Boing Boing.

Addendum:  When I published the above post last month, one of the valid comments was that the scale of the graph was logarithmic.  Let's remedy that with this new graph -

- which I found today at The Economist, accompanied by these comments:
Rebranding is always a tricky exercise, but for one field of technology 2013 will be the year when its proponents need to bite the bullet and do it. That field is alternative energy. The word “alternative”, with its connotations of hand-wringing greenery and a need for taxpayer subsidy, has to go. And in 2013 it will. “Renewable” power will start to be seen as normal...

But it is in the field of solar energy, currently only a quarter of a percent of the planet’s electricity supply, but which grew 86% last year, that the biggest shift of attitude will be seen, for sunlight has the potential to disrupt the electricity market completely.

The underlying cause of this disruption is a phenomenon that solar’s supporters call Swanson’s law, in imitation of Moore’s law of transistor cost... Swanson’s law, named after Richard Swanson, the founder of SunPower, a big American solar-cell manufacturer, suggests that the cost of the photovoltaic cells needed to generate solar power falls by 20% with each doubling of global manufacturing capacity.

Moreover, technological developments that have been proved in the laboratory but have not yet moved into the factory mean Swanson’s law still has many years to run...

Reliability of supply is a crucial factor, for the sun does not always shine and the wind does not always blow.  But the problem of reliability is the subject of intensive research. Many organisations, both academic and commercial, are working on ways to store electricity when it is in surplus, so that it can be used when it is scarce. Progress is particularly likely during 2013 in the field of flow batteries. These devices, hybrids between traditional batteries and fuel cells, use liquid electrolytes, often made from cheap materials such as iron, to squirrel away huge amounts of energy in chemical form. “Grid-scale” storage of this or some other sort is the second way, after Swanson’s law, that the economics of renewable energy will be transformed.
More at the link.  Huge implications for world (and domestic) geopolitics within our lifetimes.


  1. It should be standard building code that every building has solar energy capturing equipment on its roof.

    1. People living in Seattle would love that.

      When it makes economical sense (and it is close in some areas), more people will follow.

    2. Ask people in Mayflower Arkansas about economical sense.

  2. We should bear in mind that all the energy we currently consume, except nuclear power, is solar power. Those plants and animals that became coal and petroleum lived their lives fueled by the energy of the sun.

    1. By that logic then nuclear power is also "solar power" as those atoms were forged in the heart of a star.

  3. Our house had a solar hot water heater when we purchased it. We expanded the system and added an electric car that runs off the house solar panels. We pay nothing for gasoline and the city pays us for the excess electricity we sell to them.

    Nothing inside our house has changed, with the exception of the A/C- I can turn it down further now that I am not paying a fortune to run it. We calculated the system will pay for itself in 4.5 years when the cost savings of gasoline is factored in.

  4. Power generation needs to be (relatively) close to consumption. All the sun hitting the Sahara is no good to us.

  5. A couple of comments..

    The cost of a solar installation doesn't only include solar panels, but also includes the cost of the mounting system to put the solar system in place, plus the wiring and interfaces to hook the solar power into the household or building system. You includes at least one inverter to turn the DC solar power into the AC that is used in the house or building wiring. This increases the cost by about as much as the solar panels cost, and needs to be done both to local building code, and by a qualified electrician (Yeah, I've been looking at doing this for my house). At a minimum, you need to install (per code) a shutoff switch that is reachable outside the house -- you don't want (for example) to have a fire, and have the fire department show up and start spraying water onto your house when you are putting kilowatts of power out of your solar panels -- and possibly into the firemen.

    Now, the solar panels will put out power -- but the panels are for peak output of the panel, at the panel in perfect conditions. Over time the panels degrade, you lose power going through the inverter and the wires, etc. How you've installed your panels determine how much power you get out over a day. And of course, where you live and your local weather conditions determines how much power you get out as in more overcast areas you get less power over the year. And as I've found, you need to be careful in detail about your design -- a single shadow line (such as from a pole or a tree) can reduce the total output of your system by 70% of more.

    A good tool for estimating the power output is PV Watts, available on line at http://www.nrel.gov/rredc/pvwatts/

    I find in my area with a $0.147/kWh cost of electricity, that just considering the PV panels, for a 4 kW installation (cost of $4000) that I can save $853 in 12 years. That's a 56 year payback, just for panel costs. And we're supposed to be a very good area for solar too (US Southwest)

    Now, you can take other incentives, such as tax writeoffs, etc. A good source to check is DSIRE (www.dsireusa.org) which is a data base of federal, state, county and local incentives. I can get about 1/2 my installation paid for by other taxpayers. But even so, I'm still at about a 25-30 year payback. And I haven't paid for the installation and wiring and etc -- just the panels.

    I'm interested in doing this -- but my conclusion is it doesn't pay just yet. Maybe if you put a huge facility out in the desert where you can have economies of scale and optimize the system for power production like you can't on rooftops or sides of buildings ... Then you might make it pay.

    1. Imagine (just imagine) if we had put just 1/10 of the money spent on R&D for "traditional" energy sources into solar. We'd be in a very different place right now if we had done that since the late '70s when Carter put the panels up in the White House.

  6. And I'll add one more comment here.. I went to go look to see what it would cost for a large scale (multiple megawatt) power plant using PV. The article above was trying to compare to coal and natural gas power plants.

    California's state Energy Commission has published their best estimate for new power plants using a variety of different technologies -- including coal, natural gas, wind, solar (several technologies), geo thermal etc. They published the data in Jan 2010, so its a couple of years old. But its for new central station power plants, and is estimated on the basis of "levelized cost of energy" -- so total $/kWh including construction, financing, fuel costs, maintenance, subsidies/ incentives, etc.


    Look at Table 1, new construction with a startup date as per 2009. Since that time, natural gas costs have declined I note.

    Natural gas power plant --
    Conventional combined cycle 10.8-12.4 cents/ kWh
    Advanced combined cycle 10.0-11.4 cents/ kWh

    Coal power plant
    Advanced (IGCC) combined cycle 9.8 - 11.7 cents/ kWh

    Solar PV
    Single axis tracker, 25 MW size 26.2 - 32.0 cents/ kWh

    The solar system at that time was 2-3x as expensive as coal or gas. Since 2009, the costs per panel (again, not including wiring, installation, inverters, etc.) have dropped 50%, giving maybe a 30% net decrease in cost. That starts to put them for large dedicated installations in the competitive range.

    (And from this, I note the two fallacies from the chart shown. As I noted above, solar power plants require a lot more investment than just panels. Also, solar systems typically only produce power about 1/4 to 1/3 of the day -- when the sun is up; most at noon, and less as the sun is near the horizon. A coal or natural gas plant operates around the clock, producing power 24 hours a day. So if its costs the same $/Watt to put in a natural gas power plant, as a solar power plant, the natural gas plant will produce 3X as much power per day, as the solar field -- since its operating closer to 24 hours a day. The comparison on panel $/Watt isn't really a good one.)

  7. Not going into argument pro/vs solar energy:
    In my opinion chart is quite misleading.
    First the Y axis does not start from 0 (because of #2).
    Second whole graph has logarithmic (base 2) scale which is not at all good for comparison.

    The change in price has been much dramatic than it seems from the chart - twenty-fold!!! (in 1980 ~20$)

  8. Grid scale storage is the big unsolved problem for renewable energy. *IF* we had storage systems that can store 100's of Megawatt hours of electrical energy and release them quickly, we could really effectively use wind and solar power. People are looking at a lot of different systems which might work -- but no one has really figured it out.

    *Grins* Now, to play devil's advocate a bit..

    We do know how do do grid storage. It's called "pump storage" and is basically a dam behind which you pump water using surplus electricity, such as produced by wind in the evenings or solar during the afternoons. Then on a cloudy day, or when you need the energy back out you can just open up the petcocks and release the water to flow back downhill through turbines to produce power.

    The problem with this is this is a big new dam. And for environment concerns we have had very few major new dams approved in the US in the past couple of decades. That last major one in the US was the Rocky Mountain hydroelectric plant in Georgia -- started in 1975, and completed in 1995. So.. why don't we just put in a lot more hydroelectric dams and use them for pumped storage?

    The second devil's advocate comment is on "flow batteries" which are referenced as a great solution in the article. Flow batteries are basically reversible chemical reactions. A very simple example of this is your car battery. From a devil's advocate perspective, this typically involves very large tanks of highly reactive chemicals, usually at high temperatures. Examples of these chemical include liquid sodium and liquid sulfur -- highly reactive and at temperatures of hundreds of degrees C. Nasty stuff! You can build flow batteries -- I have a picture on my computer of a redox flow battery capable of 200 MWh operating in Japan. (As a point of comparision that would provide enough power for around 2200 average US households, for 3 days). It's about the size of high school foorball stadium, but has 100's of tons of highly reactive chemicals in that battery/ chemical plant installation. Putting these around means you need to put in lots of highly reactive chemical installations -- with their own hazards and dangers. And the safety record for these chemical plants is not the best.

    So.. there's the devil's advocate position. *If* we can solve the storage problem, renewable sources of energy become a lot better to use and work with. We have some very promising technologies -- advanced flywheels, superconducting energy storage rings, and others. People are investing money to try to make these work. But so far the field is unencumbered by success (tongue firmly in cheek).

  9. "Solar energy is not something that is going to come in overnight."

    -Gerald Ford

  10. This comment has been removed by a blog administrator.

    1. You should spend your time and money on legitimate advertising rather than spamming the efforts of hardworking bloggers.

  11. The word “alternative”, with its connotations of hand-wringing greenery and a need for taxpayer subsidy,

    When we stop subsidizing all the horrible polluting energy sectors then people can complain about subsidizing renewables, but they'll still be wrong.

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