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In most industrialized countries, solar panels account for only a quarter to a third of the overall cost of building a solar farm. All the other expenses—additional hardware, financing, installation, permitting, etc—make up the bulk of the cost. To make the most of all these other costs, it makes sense to pay a bit more to install efficient panels that convert more of the incoming light into electricity.

Unfortunately, the cutting edge of silicon panels is already at about 25 percent efficiency, and there's no way to push the material past 29 percent. And there's an immense jump in price between those and the sorts of specialized, hyper-efficient photovoltaic hardware we use in space.

Those pricey panels have three layers of photovoltaic materials, each tuned to a different wavelength of light. So to hit something in between on the cost/efficiency scale, it makes sense to develop a two-layer device. This week saw some progress in that regard, with two separate reports of two-layer perovskite/silicon solar cells with efficiencies of well above 30 percent. Right now, they don't last long enough to be useful, but they may point the way toward developing better materials.

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Hundreds of Internet-exposed devices inside solar farms remain unpatched against a critical and actively exploited vulnerability that makes it easy for remote attackers to disrupt operations or gain a foothold inside the facilities.

The devices, sold by Osaka, Japan-based Contec under the brand name SolarView , help people inside solar facilities monitor the amount of power they generate, store, and distribute. Contec says that roughly 30,000 power stations have introduced the devices, which come in various packages based on the size of the operation and the type of equipment it uses.

Searches on Shodan indicate that more than 600 of them are reachable on the open Internet. As problematic as that configuration is, researchers from security firm VulnCheck said Wednesday , more than two-thirds of them have yet to install an update that patches CVE-2022-29303 , the tracking designation for a vulnerability with a severity rating of 9.8 out of 10. The flaw stems from the failure to neutralize potentially malicious elements included in user-supplied input, leading to remote attacks that execute malicious commands.

Enlarge / Westlands Solar Park, near the town of Lemoore in the San Joaquin Valley of California, is the largest solar power plant in the United States and could become one of the largest in the world. (credit: Carolyn Cole/Los Angeles Times via Getty)

California’s San Joaquin Valley, a strip of land between the Diablo Range and the Sierra Nevada, accounts for a significant portion of the state’s crop production and agricultural revenues. But with the state facing uncertain and uneven water supply due to climate change, some local governments and clean energy advocates hope solar energy installations could provide economic reliability where agriculture falters due to possible water shortages.

In the next two decades, the Valley could accommodate the majority of the state’s estimated buildout of solar energy under a state plan forecasting transmission needs [PDF], adding enough capacity to power 10 million homes as California strives to reach 100 percent clean electricity by 2045. The influx of solar development would come at a time when the historically agriculture-rich valley is coping with new restrictions on groundwater pumping. Growers may need to fallow land. And some clean energy boosters see solar as an ideal alternative land use.

But a significant technological hurdle stands in the way: California needs to plan and build more long-distance power lines to carry all the electricity produced there to different parts of the state, and development can take nearly a decade. Transmission has become a significant tension point for clean energy developers across the US, as the number of project proposals balloons and lines to connect to the grid grow ever longer.

Enlarge / Aerial view/solar panel floating in the dam. (credit: SONGPHOL THESAKIT )

The cost of solar power has dropped dramatically over the past decade, making it the cheapest source of electricity in much of the world. Clearly, that can mean cheaper power. But it also means that we can potentially install panels in places that would otherwise be too expensive and still produce power profitably.

One of the more intriguing options is to place the panels above artificial bodies of water, either floating or suspended on cables. While more expensive than land-based installs, this creates a win-win : the panels limit the evaporation of water, and the water cools the panels, allowing them to operate more efficiently in warm climates.

While the potential of floating solar has been examined in a number of places, a group of researchers has now done a global analysis and find that it's huge. Even if we limit installs to a fraction of the surface of existing reservoirs, floating panels could generate nearly 10,000 TeraWatt-hours per year, while keeping over 100 cubic kilometers of water from evaporating.

Enlarge / The framework needed to deploy the hardware worked on Earth, so it's time to test it in space. (credit: Caltech/Momentus)

Solar power has become the lowest-cost way to generate electricity on Earth. But building it on Earth places some significant limits on how much power it can generate, with the darkness and clouds that often get in the way. So there have always been a few people who liked the idea of putting solar panels where they could produce electricity around the clock: space.

While that would get you near-24/7 power production, it comes with a collection of very obvious drawbacks: high launch costs, inability to service the hardware, and the challenge of getting the power back down to where it's needed. How these trade-offs play out in the energy marketplace has been difficult to determine, partly because the energy market is changing so rapidly, and partly because we don't really know what the space-based solar hardware would look like.

Thanks to some funding from a private donor, however, California Institute of Technology researchers have quietly been working on developing the technology needed to get space-based solar to work. And they're apparently ready to subject some test hardware to the rigors of space, thanks to this morning's successful Falcon 9 launch.

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The United States gets about 40 percent of its electricity from carbon-free sources, including renewables and nuclear, and researchers have a pretty good idea of how to cost-effectively get to about 90 percent.

But that last 10 percent? It gets expensive, and there is little agreement about how to do it.

A new paper in the journal Joule identifies six approaches for achieving that last 10 percent, including a reliance on wind and solar, a build-out of nuclear power, and development of long-term energy storage using hydrogen.

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This week, the US Department of Energy's Berkeley Lab released its annual analysis of solar energy in the US. It found that nearly half the generating capacity was installed in the US during 2021 and is poised to dominate future installs. That's in part because costs have dropped by more than 75 percent since 2010; it's now often cheaper to build and operate a solar plant than it is to simply buy fuel for an existing natural gas plant.

The analysis was performed before the passage of the Inflation Reduction Act , which contains many incentives and tax breaks that should expand solar's advantages in the coming years.

Solar, by the numbers

In terms of large, utility-scale solar installs, the US added over 12.5 gigawatts of new capacity last year, bringing the total installed capacity to over 50 gigawatts. Texas led the way, with about a third of the total capacity added (3.9 GW) going online in the Lone Star State. Combined with residential and other distributed solar installations, solar alone accounted for 45 percent of the new generating capacity added to the grid last year.

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On Monday, the Biden administration announced a suite of policy changes intended to boost the use of solar power within the US. While each individual policy change is relatively minor, combined, the changes address everything from manufacturing and importing to installation and integration with the power grid. While the administration is continuing to try to negotiate a deal that expands renewable energy via legislation, none of the initiatives announced today requires anything beyond executive action.

Who makes the panels?

At present, China dominates the manufacturing of solar cells and panels. But the Trump administration included solar hardware in its tariff war with the country. The Biden administration chose to eliminate the tariffs on the solar cells most often used in utility-scale installations but maintained them on other classes of cells. Complicating matters further, the US Commerce Department recently started an investigation into whether other countries in Asia were being used as conduits to ship panels around the tariffs.

Combined, these issues raised worries that tariffs would limit the growth of solar in the US, which is a problem given that it's the cheapest way to generate power in many areas of the country and is central to the government's plans to limit carbon emissions.

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As solar and wind energy ramps up in the United States, the industries have gotten better at installing and operating their facilities. This experience can be seen in how the facilities are financed. According to new research , people working in the fields—and adjacent ones—have learned to be more efficient, reducing the overall cost of power. Further, according to Mark Bolinger, a research scientist at Lawrence Berkeley National Laboratory and one of the authors of the paper, this so-called learning rate can be extrapolated into the future, and it spells good news for the two renewable sources of energy.

“The people who operate these turbines naturally get better over time as they do more of it. They get more efficient, and it allows them to lower their costs a bit,” Bolinger told Ars, adding that the same holds true for the workers manufacturing the facilities. “Some of them have been doing it for a really long time… All things being equal, that should lead to a reduction in manufacturing costs.”

There’s a large amount of literature on learning rate and learning curve theory, he said. Moore’s Law, which pertains to the power of silicon computer chips, says that the number of transistors per silicon chip doubles each year. Bolinger said that the learning rate in these renewable energy operations is similar to that. Learning rate is a measure of how much cost declines for each doubling of cumulative output, he said.