13 March 2015

Solar power on the rise

From Mother Jones:
New data from market analysis firm GTM Research finds that 2014 was solar's biggest year ever, with 30 percent more photovoltaic installations installed than in 2013...


  1. Back in the early 1970s, I had such high hopes for solar power. Alas, it never came to pass.

    About 15 years ago - about the start of this chart - I found out why solar just isn't going to ever pan out:

    The available watt density is just too low.

    As impressive as this chart may look at this scale, I just yesterday looked at a chart of the nuclear power plants in France - 60 of them. The average output was 1.1 gigawatts. That is one country, also, as is the solar numbers chart.

    This chart here shows ALL of the solar for the year. 6 gigawatts.

    I won't even ask how much land/roof area was needed for that 6 megawatts.

    Starting from nothing, it is easy to think that inroads are being made. But the INCREASE in world energy needs is more than the total 6 gigawatts shown - much less the 1.5 gigawatt increase from 2013-2014. If solar grows at only 1.5 gigawatts per year, it would continue to fall behind, faster and faster.

    The energy of sunlight on the surface of the Earth is only 1367 watts per square meter - about 127 watts per square foot. That is when the sun is shining directly down on the ground, and when the sunshine is brilliant. Using a factor for latitudes farther north, and adjusting for seasons, one would use the cosine of the latitude. At 40°N that is 0.766 - giving only 97 watts per square foot. Allowing 80% efficiency for energy losses in the solar cells and transmission and storage and conversion, reduce that to 78 watts per square foot.

    Then, of course, solar doesn't work at night, and the energy level on cloudy days is reduced - and is spotty on partly cloudy days.

    On such occasions solar needs to have a backup system. And the backup system has to have 100% of the needed capacity in a region. This means that even if solar handled the full needs of a region a duplicate power generation system is needed, one that is not contingent on the sun. And that one would need to stay fired up and ready, at a moment's notice.

    Stan, I am emotionally with you on solar, but damned if the numbers never look worth much. I wanted solar to work back in the 1970s as much as anyone. But as good as you seem to think this chart bodes for the future, it only tells me that solar is falling farther and father behind.

    Just sayin'...

    1. Hi Steve -

      I was with you in the 70s, and put some investment $ in shares of solar companies, both of which went paws-up. To me the biggest improvement in recent years has been the development of what you might call "micro-solar", with small units that can be deployed in off-the-grid third-world situations to provide a modicum of power to a shack in Africa or rural Asia, allowing a family to have light at night or water from a pump.

      I agree with you re the low density of power and the limited upside max.


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