Solar power plants can consist in either PV panels or mirrors that focus sunlight on a fluid that boils and turns a turbine ("concentrating solar power," or CSP). In practice, most new solar plants these days use PV, which has gotten so cheap so fast that it’s outcompeted CSP and every other solar segment, at least for now.
In 2007, there were zero utility-scale solar power plants in the US. Today there are hundreds, ranging from the 579 MW Solar Star project (the world’s largest solar farm) in California down to dozens upon dozens of 10, 20, and 50 MW projects in communities across the country. (SEIA counts 2,100 solar PV projects over 1 MW.)
Big solar power plants still provide a measly 0.6 percent of overall US electricity. But they are headed up a steep growth curve.
Residential rooftop solar is the fastest growing solar segment, but utility-scale solar is bigger. There’s more installed, so even with its slower growth rate it adds more capacity each year, in 2015, it accounted for 57 percent of all new installed solar capacity.
There’s a ton of utility solar in the pipeline. According to the Energy Information Administration, 9.5 GW of utility solar is scheduled for installation in 2016, more than from any other single energy source, including natural gas.
That would make 2016 a banner year, with utility solar accounting for more than three-quarters of installed solar capacity, installing more in a year than in the past three combined. That’s serious growth. A new report from GTM Research is also optimistic about utility-scale solar passing something of a milestone in 2016.
According to the 2015 Lawrence Berkeley National Laboratory report, the installed cost of big solar has fallen 50 percent since 2009, from $6.30/W to around $3.10/W at the end of 2014. Some projects were down as low as $2/W when LBNL released its report. And these days, solar projects in North Carolina and Georgia regularly report costs as low as $1.15/W.
The stretch goal of the Department of Energy’s 2011 Sunshot Initiative is to drive installation costs down to $1/W, which it says "would make solar without additional subsidies competitive with the wholesale rate of electricity, nearly everywhere in the US."
The thing about solar power is you know exactly how much it’s going to cost, forever. (At least for the life of a solar PV installation.) Coal and natural gas have highly volatile prices. The price of sunlight is zero. There is no fuel cost.
That means the costs of the produced electricity can be calculated in advance, based on capital and operation and maintenance costs. It’s more like building infrastructure than like operating a commodity-based asset.
This allows solar developers to offer utilities extremely stable, long-term power purchase agreements, or PPAs. For a utility in these turbulent times, knowing exactly how much power is going to cost for the next 20 (or more) years is a great comfort. That kind of risk hedging is worth money.
There are now as many Republicans as Democrats with solar power plants in their districts (and more Republicans with wind farms). The reason red districts are catching up (and pulling ahead) so fast is that they are more likely to be rural and have open, cheap land to attract developers. (Rural North Carolina, for instance, is going nuts over solar, in all kinds of ways.)
Big solar used to be almost entirely driven by policy, mainly state renewable energy standards and federal tax credits. It has all but outgrown the first and will outgrow the latter over the next five years.
It’s about to stand on its own two feet, outcompeting even rivals that are allowed to dump carbon emissions into the atmosphere for free. It won’t be long before the discussion about environmental benefits is moot, utilities will demand solar because it’s the cheapest power available.