Solar power stations are a moronic waste of taxpayers money. This from a guy (me) who lives off grid and depends on solar for electricity. Works fine for me and those who chose to invest and grid tie. The problem isn't the low energy density of solar but it's intermediacy. Same with wind, which on a yearly average generate less than 20% of rated power.
For various reasons, anything more than about 25% unreliable power disturbs the grid. Very little can be done to alleviate that.I want to tease apart the issue of solar power intermittence because it is core to the discussion of how solar power might fit into the energy generation "ecosystem".
From the demand side
The first thing that I want to point out is that our energy consumption is intermittent.
The troughs average about 150 million metric tons of CO2. The peaks since 2000 are an additional 75 million metric tons. That is, peak summer demand is 50% higher than base load.
|Data from Eastern Kentucky|
|Green bars are electric usage while black line is average temperature|
The picture in my head is that mom and dad come home from work, throw a pizza in the oven and kick on the A/C.
So where does that leave us?
Peak demand occurs in the summer when peak sunshine occurs. That is good.
Peak demand occurs from 3 PM-through-10 PM, six hours AFTER peak sunshine. That is not good.
Most of the peak demand is associated with cooling. That ends up being favorable.
The inside temperature lags the outside temperature due to the inertia like effects of the structure's thermal mass. The walls and floor and ceiling and appliances all hold heat. They are a buffer or a thermal battery, if you prefer. It is expensive to store electricity but it is cheap to store heat.
The current propaganda tells us to turn off climate control when there is nobody home. The propaganda would have to change if we were to exploit the "thermal battery" capabilities of our homes. We would have to chill them down during the day while we were at work and turn off the A/C in mid-evening.
And, at least for the people on the East Coast, due to the fact that the sun is higher in the sky 1500 miles west of them. Their 6:00 PM (eastern edge of EST) peak can be fed by 4:00 PM (almost Mountain Zone) sunshine in western Kansas.
Weather related intermittency
In a word, Clouds.
|2016 Winter Storm Tracks|
|Here is one set of choices. Garden City, Kansas, Midland, Tx and Truth-or-Consequences NM are all about 400 miles apart. It would be a rare storm when all three are socked in.|
Since individual storms are of finite size, one way to deal with them is to have several, widely separated solar farms.
|From Wikipedia. It is the A/C, stupid.|
Another point in favor of western solar farms is that southern cities tend to consume more electricity per capita than northern cities.
Distributed vs. Centralized
There are enormous economies of scale when it comes to electrical switching and handling. Instead of millions of over-sized, air-cooled, DC-to-AC switching units baking in the sun atop roofs across America, The heavy lifting can be handled by relatively few, water-cooled units at each "farm".
|Image from Lazard. Rooftop Residential solar costs about $175 per MWh while Utility Scale solar costs about $50 per MWh.|
How much solar?
I could see "sizing" solar to handle 30% of the US peak load. That is the variable component attributable to Air Conditioning which synchronizes closely with peak annual and daily solar power...or at least close enough. After that it becomes harder to justify solar power.