Proponents of renewable energy have long made the case that although upfront costs might be higher, green is the way to go for a cleaner, more sustainable future. But coal powerplants were cheaper to build, and bean counters often go with whatever's cheaper in the short term.

There was no getting around it: Coal simply cost less. Or at least it used to. Last year we reached grid parity in the United States—the day when two competing energy generators cost the same to build.

Now we can finally look at advantages beyond price. First, everyone would rather live near a solar array than a coal plant. Second, clean-energy jobs pay better than jobs in fossil fuels. Third, and somewhat surprisingly, solar actually disrupts land less than coal does for the same energy generation. In the past, these and other arguments for utility-scale solar were always met with, "But coal's cheaper." Not anymore.

What's Ahead?

We can now anticipate technological breakthroughs accelerated by wider solar deployment in both the residential and industrial spaces.

Leading solar equipment distributor CED Greentech recently assessed the ever-evolving field of energy storage and thinks that some big battery breakthroughs could be on their way. Here are two emerging technologies that could bring benefits especially to residential solar.

Solid-state batteries.
Solid-state batteries use lithium ion, the 1980s storage solution that has found widespread use in electronics (like your smartphone) and which is "quickly becoming the preferred option among solar customers," per CED Greentech. The difference is the solid-state version contains no liquid. The electrolyte is solid, rather than liquid and flammable.

Such batteries are already used in small medical implants, and research shows that scaling up the solid-state electrolyte could make the batteries "the next big innovation in renewable energy storage" for both homes and city grids.

In the past, arguments for utility-scale solar were always met with, "But coal's cheaper." Not anymore.

These batteries offer two compelling benefits over their liquid counterparts. First, researchers believe they can double the energy density. Second, these batteries probably won’t need cobalt, a metal that gets more expensive every day. The result could be smaller yet more powerful and less expensive batteries for home solar energy systems.

Gold nanowire.
A thousand times thinner than a hair on your head, gold nanowire has proven to be too fragile to withstand multiple charging cycles. If not for that, its high conductivity and large surface area would make nanowire "quite the candidate for an advanced battery material," writes New Atlas.

But now, researchers claim that a nanowire-based electrode with a special protective coating can be recharged again and again. Potentially, this electrode could find its way into batteries that can withstand hundreds of thousands of recharge cycles—with no signs of degradation! Such batteries could keep working excellently long after today's standard home solar batteries have reached the end of their lifespan.

The Road to Grid Parity

Pricewise, solar and offshore wind power had been nipping at coal's heels for some time. In 2019, these renewables reached parity with average wholesale prices in California and China.

Major European markets reached parity around the same time. Researchers analyzing Germany, France, Italy, and Spain concluded that investments in new renewables were as financially feasible as investments in fossil fuels. What's more, rooftop solar in those countries would save homeowners serious euros: Germany, 49%; France, 44%; Italy, 42%, Spain, 23%.

Authors of the study, published in Science Direct, wrote that "parity of rooftop PV is already possible in many EU countries and without subsidies. Further cost reductions in the PV technology sector coupled with increases in the systems' efficiency will increase rooftop PV competitiveness."

In America, 2020 was our year.
We reached grid parity in 2020, according to Jeffrey Sachs, a professor at Columbia University. He has watched utility-scale energy projects evolve over the years. "Renewable energy now is at what is called grid parity," he told CBS News. "That means it is no more expensive to put up a solar field than it is to put up a coal plant."

Solar disturbs less land than coal. "The land footprint of coal is about 20% bigger than the land footprint of solar thermal," writes Ted Nace for Grist.


Grid parity is a milestone a long time coming. As we've seen when we reached past milestones that mark the arrival of a new technology at an old price—affordable LCD televisions, excellent touchscreens, GPS, Wi-Fi—progress can leap ahead, sometimes in unexpected directions.

One thing is for certain: Now that cities can build solar fields for no more money than coal plants, advances will be made. The best advances could find their way onto our rooftops and into our solar-energy storage solutions. Is solar a good fit for your roof? Check out your options here.