Did your calculation include installing 4 W (peak) of PV to produce 24 Wh/day of power, compared to installing 1W (peak) of coal plant to produce 24 Wh/day?
It's all reduced to $/W at a high level, so yes. But, keep in mind it's a
simple high-level analysis and the devil's in the details. Need to find an actual solar plant (perhaps the one
@Ampster mentions) with energy storage to get some real-life costs.
There may never be enough batteries to supply the U.S. grid overnight, given quantities of elements such as lithium or lead required.
That's a good point,
googling it seems like there is -- but will there be as power consumption goes up? Same concern for Vanadium flow batteries. There are new technologies (e.g., glass batteries) increasing the power density so it'll take less resources in the future. Perhaps someone will find a way to make
gravity batteries practical or a break though for
high power density supercapacitors (they just made a
10x jump, but still not quite there yet).
Other energy storage can include pumped hydro.
Very true. Hydropower isn't available everywhere, but some countries (e.g., Norway, New Zealand) are really big on hydro. From a quick google a Wisconsin plant has
$0.85/kWh, which I believe is opex, so that's noise compared to capex.
This site lists $1.50-$2.50 Wh, so for solar with 3 days storage that's $6.50/W to $9.50/W. Of course, at the end of 10 years the dam will still be there.
...I think fossil fuel plants can can fill in during a transition period...
I believe that transition period has
just started; it's just not recognized as such yet ... but it seems inevitable. As the cost of energy storage devices fall utilities will deploy more of them... see
How will Batteries change the world? According to this ref, with as little as 5% power supplemented from fossil fuels; solar and wind are economical when energy storage hits $150/kW (which it has now and is expected to go to $100 by 2023).
