How Cheap Can Solar Get?

Monday, August 24th, 2015

How cheap can solar get, without subsidies, as a function of scale, if current trends hold?

Solar Cost Projections

Comments

  1. Bob Sykes says:

    In one way, the cost of solar ($/kWh generated) is not important. Intermittency is the killer. The capacity factor for solar has to be under 50% even in the best desert sites, and it is more likely 25% or less in those sites. This means that every kW of solar requires a kW of conventional power. In fact, the conventional power will have to supply the great majority of the demand, and solar will be just an occasional supplement.

    Because of its rapid response capability, the usual primary source coupled with supplemental solar/wind is a natural gas-fueled turbine. However, the turbine must be run at low power levels continuously even when solar/wind is online. This means that solar/wind continuously emits carbon dioxide.

    At present, solar/wind is a tiny portion of our electric supply, and the required “backup” comes out of the system surplus. Obama is greatly reducing that surplus, and his actions will gradually reveal the problems with wind/solar. Chief among them is the distribution network instability cause by wind/solar intermittency. The German experience is the wind/solar creates serious stability problems when it reaches about 4% of total supply.

    The ice cores at Lake Vostok and the recent global warming show that temperature increases lead carbon dioxide increases. The increased CO2 is likely due to ocean outgassing. We are in the process of wrecking out economy because of a New Age superstition.

  2. Tryptophan says:

    What makes you think that a gas turbine must be run constantly, Bob Sykes?

    My understanding was the opposite. I thought they could easily be switched off, because they function like a jet engine. Most of the cost of gas power is the cost of the gas itself, so the additional cost of backup turbines is not vast.

  3. Dan Kurt says:

    Sykes is right. Find and talk to an “operator” of an electric utility. My wife’s cousin is married to one and he will talk you ear off on the folly of solar & wind integration with the power net: politics not prudent power engineering.

    Two points:

    1) unlikely rosy scenario for decrease in cost and increase in efficiency of solar cells, time will tell;

    2) solar may work if the arrays of solar cells are in near earth orbit.

  4. David Foster says:

    Looks like you’ll pay about $1000/kW for your peaking turbine. I haven’t read this carefully, but believe it includes the generator and auxiliary equipment.

    If you run it at full capacity for 1000 hours/year on average (remember, this is just for backup when the solar doesn’t sol or the wind doesn’t blow), and you pro-rate the costs (simplistically) over 10 years, then the capital cost is 10 cents per kWh. Add 2 or 3 cents for operations & maintenance, then you’ll need to add in the cost of the fuel.

  5. Isegoria says:

    It’s definitely a mistake to equate one kWh of solar energy with one kWh of reliable, baseline energy from coal, gas, nuclear, etc. — but it’s also a mistake to conclude that it’s therefore useless. Long before we had a grid, we used intermittent wind power to pump water, for instance. Cheap solar would be disruptive in Clayton Christensen’s original sense:

    Generally, disruptive innovations were technologically straightforward, consisting of off-the-shelf components put together in a product architecture that was often simpler than prior approaches. They offered less of what customers in established markets wanted and so could rarely be initially employed there. They offered a different package of attributes valued only in emerging markets remote from, and unimportant to, the mainstream.

  6. Alrenous says:

    Peak demand is not only usually during the day, but usually near noon.

    If solar could be used to blunt the peak, conventional plants could be run near capacity significantly more, causing a price drop disproportionate to the direct supply increase.

  7. Anomaly UK says:

    To flesh out the “disruptive” scenario: if solar is unsuitable for the grid (as Dan says), yet becomes very cheap, then homes & industries start to work with two kinds of power: cheap, unreliable power to be used opportunistically as it arrives, and expensive, reliable grid power for essentials & emergencies. That doesn’t simply mean a partitioning of today’s uses into the two buckets, it potentially means new uses happening, and some old routine uses becoming luxuries. (Think of people abandoning broadcast TV or five-nines-reliable landline phones for cheap, flexible but less dependable alternatives).

    There are a few “if”s there, it seems to me just as likely that either solar does get integrated with the grid, or else never becomes so cheap as to be a large proportion of supply, but in between, that window does exist.

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