21 Solar
21.1 Software drives Solar Costs
Software will eat solar: Driving utility-scale solar prices below 1 cent per kilowatt-hour by 2025
Terabase Energy is on a mission to get utility-scale solar power prices below $0.01 per kWh by 2025 using software, as opposed to the DOE’s hardware strategy.
Terabase Energy is on a mission to drive down utility-scale solar power prices to less than $0.01 per kilowatt-hour by 2025, by using software, automation and modeling to optimize power-plant operation. The VC-funded startup just acquired another startup to help realize that goal.
Terabase’s aggressive cost target far exceeds the U.S. DOE’s SunShot 2030 goal of $0.03 per kWh for utility-scale photovoltaics by 2025. The DOE’s most recent solar funding went toward hardware improvements in nonsilicon solar approaches such as perovskites, cadmium-telluride thin films and next-generation concentrated solar power. The DOE target cuts the cost of solar energy by 60% within the next 10 years.
But the 82% reduction in solar cost over the last decade (according to the International Renewable Energy Agency) came from economies of scale, better technology and supply chains at largely silicon-based solar plants, not the alternative technologies being funded by the DOE.
And even silicon module pricing might be nearing the bottom of the cost curve: “The era of ever-declining solar module prices is largely behind us,” according to Yan Zhuang, president of Canadian Solar’s manufacturing operation, as reported in pv magazine. Global commodities such as aluminum and glass are a larger part of the solar module bill of materials. Software is eating solar
It’s software, not hardware, that’s going to drive down utility-scale solar costs, according to Terabase, a startup that closed a $6 million Series A round late last year and has already made a small acquisition to further develop its platform. Terabase just acquired REPlant Solutions, a spinout of First Solar that makes solar power plant controls and has developed a 1.5-kilovolt direct-current (DC) architecture and a DC trunk bus.
REPlant’s plant controller operates the solar power plant, acting as the ringmaster in an increasingly complicated process.
Matt Campbell, Terabase CEO, tells Canary Media: “In the future…PV plants will become even more demanding, requiring sophisticated plant controls, the integration of storage, and hybridization with wind and other forms of generation.” The acquisition of REPlant adds advanced supervisory control and data acquisition (SCADA) and other controls systems to Terabase’s toolbox.
REPlant has an installed base of more than 10 gigawatts across 80 solar plants.
Big solar is more manufacturing than construction
While solar hardware has gotten cheaper, soft costs are still stubborn and represent a more significant piece of the total project cost (a similar situation to the residential and commercial solar segments).
“We have to keep fighting to reduce the cost,” said Campbell. “There’s a big difference between solar at 1 cent per kWh versus 1.5 cents per kWh.”
In an earlier interview, Campbell said that he wants to eliminate the construction mindset: “Utility-scale solar is more manufacturing than construction, with tens of thousands of identical units. It’s not complex like a dam. It’s just big. […] It needs to be managed like row-crop farming and more of a modern, integrated supply chain. Most projects are still managed on Excel spreadsheets.”
The way to get to super-cheap solar, according to the CEO, is with smart software “across the whole life cycle” — from procurement, to oversight of construction, to operations — “all on a common interconnected digital platform.”
Terabase recently provided digital and engineering services for the 800-megawatt Siraj-1 solar power plant in Qatar, which will sell its power for $0.01449/kWh. (These low utility-scale solar cost numbers tend to happen in global markets with lower labor costs than the U.S.)
21.2 Efficiency
Stevenson
To make a really efficient device, it is tempting to pick a material that absorbs all the Sun’s radiation – from the high-energy rays in the ultraviolet, through to the visible, and out to the really long wavelengths in the infrared. That approach might lead you to build a cell out of a material like mercury telluride, which converts nearly all of the Sun’s incoming photons into current-generating electrons. But there is an enormous price to pay: each photon absorbed by this material only produces a tiny amount of energy, which means that the power generated by the device would be pitiful.
A better tactic is to pick a semiconductor with an absorption profile that optimizes the trade-off between the energy generated by each captured photon and the fraction of sunlight absorbed by the cell. A material at this sweet spot is gallium arsenide (GaAs). Also used in smartphones to amplify radio-frequency signals and create laser-light for facial recognition, GaAs has long been one of the go-to materials for engineering high-efficiency solar cells. These cells are not perfect, however – even after minimizing material defects that degrade performance, the best solar cells made from GaAs still struggle to reach efficiencies beyond 25%.
Further gains come from stacking different semiconductors on top of one another, and carefully selecting a combination that efficiently harvests the Sun’s output. This well-trodden path has seen solar-cell efficiencies climb over several decades, along with the number of light-absorbing layers. Both hit a new high last year when a team from the National Renewable Energy Laboratory (NREL) in Golden, Colorado, unveiled a device with a record-breaking efficiency of 47.1% – tantalizingly close to the 50% milestone (Nature Energy 5 326). Until then, bragging rights had been held by structures with four absorbing layers, but the US researchers found that six is a “natural sweet spot”, according to team leader John Geisz.
Getting this far has not been easy, because it is far from trivial to create layered structures from different materials. High-efficiency solar cells are formed by epitaxy, a process in which material is grown on a crystalline substrate, one atomic layer at a time. Such epitaxial growth can produce the high-quality crystal structures needed for an efficient solar cell, but only if the atomic spacing of each material within the stack is very similar. This condition, known as lattice matching, restricts the palette of suitable materials: silicon cannot be used, for example, because it is not blessed with a family of alloys with similar atomic spacing.
Devices with multiple materials – referred to as multi-junction cells – have traditionally been based on GaAs, the record-breaking material for a single-junction device. A common architecture is a triple-junction cell comprising three compound semiconductors: a low-energy indium gallium arsenide (InGaAs) sub-cell, a medium-energy sub-cell of GaAs and a high-energy sub-cell of indium gallium phosphide (InGaP). In these multi-junction cells, current flows perpendicularly through all the absorbing layers, which are joined in series. With this electrical configuration, the thickness of every sub-cell must be chosen so that all generate exactly the same current – otherwise any excess flow of electrons would be wasted, reducing the overall efficiency.
21.3 Mediterranean
Tooze
The Mediterranean has always been a conduit for energy. From the days of Roman dominance to the nineteenth century it was manpower in the form of slaves. Today it is mostly natural gas. Half-a-dozen pipelines connect Europe to Africa and the Middle East. The eu depends on the region for over a third of its natural-gas imports. In the age of renewable energy, countries on the Med boast some of the best conditions on Earth for harvesting natural forces.
Solar capacity shows vast potential (see map). Spain basks in a daily average of 4.6 kilowatt-hours (kwh) of sunlight per square metre and Morocco in 5.6kwh, double what Germany can expect. Sparse populations mean that Spain and Portugal have ample land for such plants, as do the deserts of north Africa and the Middle East. In parts of Morocco and Mauritania both sun and wind are abundant, forming rare sweet spots where electrolysers can run virtually non-stop. “There are only ten such locations around the world,” explains Benedikt Ortmann, who runs the solar business of BayWa, a German energy and construction company.
21.4 Solar Waste
Smith
We’ve switched to panel technologies that don’t contain most of these chemicals:
US state health departments list a range of potential toxins in solar panels: arsenic, gallium, germanium, and hexavalent chromium.
Except, most panels are crystalline silicon or cadmium telluride (CdTe), which don’t have arsenic, gallium, germanium, or hexavalent chromium in them. More information on where some of these claims might come from is in the footnote.5
The only health concern from solar panels is the small amounts of lead in silicon panels and trace amounts of cadmium in CdTe ones. The International Energy Agency flags these as the only potential human health risk too.
In fact, engineers are working at removing the small amounts of lead from solar panels as well.
Once again, solar skeptics are inveterate techno-pessimists, and consistently underestimate humanity’s ability to innovate around early technological hurdles. Solar waste problem is not going to be a deal-breaker.
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