Lazard’s recent 2026 Levelized Cost of Energy+ report again identifies utility-scale solar as one of the least-expensive sources of new generation, with an unsubsidized LCOE of approximately $40 to $61 per MWh. Yet Lazard also emphasizes firming costs, capacity accreditation, and the importance of evaluating renewable resources within regional reliability frameworks, not simply by their average cost of production.
That distinction matters because solar’s lowest-cost electricity frequently arrives when its market value is lowest. On bright spring afternoons, PV production can exceed demand or transmission capacity, producing negative prices and curtailment. The conventional response is to reduce output from an asset that is technically capable of producing more electricity. The better question is: What productive process could absorb that surplus?
Geo2Watts has developed the Borehole Battery™ Platform, or BBP, around that opportunity. Instead of treating excess PV generation as an oversupply problem, the BBP would use it as charging energy for a high-temperature heat pump. Electricity drives a compressor that increases available heat and transfers it through a closed-loop water system into repurposed idle oil and gas wells, where the energy is stored at temperatures limited to approximately 200°C. During evening peaks or other high-value periods, the stored heat drives an expander-generator to produce dispatchable clean electricity.
This is not geothermal generation. The wells do not supply naturally occurring underground heat. They function as engineered thermal storage vessels charged by electricity that might otherwise be curtailed.
For the PV industry, the BBP offers a different way to think about solar-plus-storage. Rather than beginning with the cost of the storage device, the analysis begins with the value of the charging electricity. A curtailed solar megawatt-hour has little or no immediate revenue value. Redirecting otherwise-curtailed solar generation into long-duration thermal storage allows that energy to be delivered later as firm capacity, peak-period electricity, microgrid power, or resilient backup power.
The concept complements PV by converting surplus solar production into dispatchable power rather than allowing it to be curtailed. PV modules generate direct current, which inverters convert into grid-compatible AC electricity. The BBP can use that AC power to drive proven motors, compressors, heat exchangers, and controls during charging, storing the energy as heat in repurposed idle wells. When solar output declines or grid demand rises, an expander-generator converts the stored heat back into synchronous AC electricity, extending the value of PV beyond daylight hours.
Lazard notes that solar, wind and storage are expected to dominate near-term U.S. capacity additions because of their relative cost and deployment speed. It also reports that standalone storage costs increased in 2026 after recent declines, while solar’s near-zero marginal operating cost strengthens the case for optimizing electricity from existing renewable assets.
Lazard’s report does not prove that the BBP is less expensive than conventional battery energy storage systems. It does, however, show why the comparison is increasingly important: storage costs are rising, the value of firming solar generation is growing, and project economics now depend heavily on duration, location, existing infrastructure, and the ability to convert otherwise-curtailed solar power into dependable capacity.
That is the essence of GridValue™, a concept developed by Geo2Watts to describe the economic value of an energy resource beyond its standalone LCOE or LCOS. GridValue™ asks not only what it costs to generate or store a megawatt-hour, but also when and where that electricity can be delivered, how long it can be sustained, how quickly the project can be deployed, and what existing infrastructure can be reused. It incorporates factors such as curtailment avoidance, storage duration, dependable-capacity value, interconnection constraints, brownfield redevelopment, permitting risk, safety, supply-chain exposure, useful life, and bankability.
The PV industry has already mastered harvesting sunlight. Its next opportunity is ensuring that fewer solar electrons are ever thrown away, and GridValue™ provides the broader economic framework for measuring how effectively those electrons can be captured, stored, time-shifted, and delivered as dependable power when and where the grid needs them most.
The views and opinions expressed in this article are the author’s own, and do not necessarily reflect those held by pv magazine.
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