Honestly, we don’t enjoy debunking renewable energy innovation. And it’s actually not the technologies as much as it’s the media coverage that gets us going. In a connected world where one credulous story can set off a chain reaction of hype and misunderstanding, a little scrutiny can’t be a bad thing, can it?

The latest instigator: the Guardian.

The technology: Stirling engine solar power systems.

In a story last week that drew wide attention (thousands of shares, hundreds of comments, several pickups by other outlets), the Guardian presented a “new” solar electric generating system and asked, in the headline: “Could this be the world’s most efficient solar electricity system?”

To which we reply: No. And: Even if it were, that achievement alone is virtually meaningless.

Beyond possible advantages in land use, which aren’t evident here, efficiency matters only so far as it drives down cost. If a system costs vastly more to achieve marginal efficiency gains, that’s a losing proposition. Tellingly, there’s nothing in the Guardian article to indicate that the concentrating solar power system it profiled can beat photovoltaic solar.

You know. PV. Good stuff. Cheaper and more efficient than ever – as long as you don’t try to make a road out of it.

In fact, this “new” solar technology written up in the Guardian isn’t new it all. Using a dish collector to drive a Stirling engine was supposedly on the precipice of doing big things five years ago when it collapsed in a heap. And here’s the kicker: The cause of its demise was the falling price of photovoltaic solar – which has only gone on to become far less expensive.

The Irish renewables firm NTR made perhaps the highest-profile attempt to bring this technology to commercial deployment, through a couple of subsidiaries, the manufacturer Stirling Energy Systems (SES) and the project developer Tessera Solar. The companies worked with engineers at Sandia National Laboratories on the “SunCatcher” system.  As Sandia explained back in 2009, when a new and improved SunCatcher was ready for commercial deployment:

The modular CSP SunCatcher uses precision mirrors attached to a parabolic dish to focus the sun’s rays onto a receiver, which transmits the heat to a Stirling engine. The engine is a sealed system filled with hydrogen. As the gas heats and cools, its pressure rises and falls. The change in pressure drives the piston inside the engine, producing mechanical power, which in turn drives a generator and makes electricity.

By early 2010, an array of SunCatchers had indeed gone up, 60 25-kilowatt units with a generating capacity of 1.5 meagawatts in Arizona, feeding power to the Salt River Project. Here’s YouTube video of them in action. Turn down your volume before you play the video – those engines are loud.

There were plans in the works to do more installations. Tessera, the development company, even had power purchase agreements for huge plants in Southern California, plants totaling more than 1,500 MW.

But by September 2011, SES, the manufacturer, was in bankruptcy and the Arizona project was being decommissioned. Cause of death: As Greentech Media’s Eric Wesoff put it back in 2013 when yet another hopeful, Infinia, had gone down, “Stirling engines are another utility-scale solar technology done in by crystalline silicon and cadmium-telluride solar panels.”

PV projects now cost half (or less) what they did in 2011. If Stirling engine solar couldn’t compete then, how can it compete now? The big thing concentrating solar power can bring to the table over PV is thermal storage – but not this kind of CSP.

Ripasso Energy, the company written up in the Guardian, is said to be on the verge of commercial deployments after four years of testing in the deserts of South Africa. Much luck to them! When there are indications of a cost breakthrough, we’ll let you know.