MIT Study: 81 Innovations That Cut Solar Costs by 99%

Solar panels cost more than 99% less than they did in the 1970s. A 2025 MIT study set out to explain exactly how that happened.

The researchers identified 81 innovations that drove solar costs down, and many of them didn't come from the solar industry at all. They came from semiconductors, metallurgy, glassmaking, oil and gas drilling, construction, software, and utilities.

Here is what the MIT study found, why it matters, and what it suggests about solar's next chapter: getting more from systems that are already built.

What Did the MIT Study Find About Solar Costs?

MIT researchers identified 81 unique innovations that affected the cost of solar power systems since 1970, a period in which solar panel costs fell by more than 99%. The study, led by MIT professor Jessika Trancik, was published in PLOS ONE in August 2025.

The research team included Goksin Kavlak of the Brattle Group, Magdalena Klemun of Johns Hopkins, Ajinkya Kamat, and Brittany Smith and Robert Margolis of the National Renewable Energy Laboratory.

Their goal was to trace cost declines back to specific advances, rather than treating them as a vague result of "scale" or "learning."

Trancik summed up the finding: "Our results show just how intricate the process of cost improvement is, and how much scientific and engineering advances, often at a very basic level, are at the heart of these cost reductions." In other words, no single breakthrough made solar cheap. Dozens of them did, often in fields that had nothing to do with energy.

Where Did Solar's Cost-Cutting Innovations Come From?

Many of the most important advances behind cheaper solar came from outside the solar industry, including semiconductor fabrication, metallurgy, glass manufacturing, oil and gas drilling, construction, software, and electric utilities.

Examples of how other industries contributed:

• ●Semiconductors. Chipmaking advances helped make solar cells more efficient.
• ●Metallurgy. Better processing of silicon and metals.
• ●Glass manufacturing. Improvements like anti-reflective coatings.
• ●Oil and gas. Drilling and materials expertise that fed into production processes.
• ●Construction and software. Faster installation methods and digital tools.

That story is more collaborative than the usual clean energy narrative. Solar got cheap because many industries' breakthroughs stacked on top of each other.

Solar's cost story isn't a moonshot. It's decades of borrowed breakthroughs adding up.

Why Did Hardware Costs Fall Faster Than Soft Costs?

The MIT study found that hardware innovations drove most past cost improvements, while "soft" factors like permitting contributed significantly less. Balance-of-system costs depend heavily on those soft technologies.

Solar costs fall into two broad buckets:

• ●Modules. The panels themselves, which got cheaper through better designs, materials, and automated manufacturing.
• ●Balance of system. Everything else, including inverters, racking, labor, permitting, and financing.

Trancik put the problem plainly: "Often, it comes down to delays. Time is money, and if you have delays on construction sites and unpredictable processes, that affects these balance-of-system costs."

Why Do Permitting and Soft Costs Matter So Much Now?

As panel prices have fallen, soft costs like permitting, labor, and financing make up a larger share of what a solar project costs, so speeding up those processes has become one of the biggest remaining opportunities.

That's why states are experimenting with automated permitting. New Jersey passed a smart solar permitting law that will issue near-instant permits for residential systems. In New York, Kingston adopted SolarAPP+ for automated approvals.

Every week of delay adds cost. Cutting those delays makes projects cheaper without any change to the hardware.

What Does This Mean for the Next Chapter of Solar?

Solar's next chapter isn't only about new projects. It's about getting more value from the aging systems already in the ground. Many were built under older rules with older equipment, and many are underperforming.

The same kind of cross-industry innovation that cut costs can be applied to repowering:

• ●More power from the same footprint. Modern panels and inverters produce more from the same roof or site.
• ●Longer system life. Replacing the components that wear out first extends a system's useful life.
• ●Renewed value for early adopters. Owners and host communities keep benefiting from projects they backed years ago.

New technologies keep arriving too. Perovskite-silicon tandem cells are moving toward mass production, which could raise output again.

Why Does the Repowering Opportunity Keep Growing?

Each year, more of the U.S. solar fleet reaches the age when inverters fail and panels have degraded, while modern equipment produces far more than the hardware it replaces.

That combination makes repowering attractive. An older system already has land, permits, and a grid connection, and those soft-cost hurdles are exactly what the MIT study found hardest to cut.

Repowering skips most of them. It upgrades the hardware, where cost improvements have been largest, while reusing the site and interconnection. We break down the process in what solar repowering involves.

It also matters more as federal credits for new projects wind down. As we covered in why solar's record growth runs on credits Washington is now ending, new builds face a harder road ahead.

Start With a Ballpark Estimate

Solar has always moved forward by building on earlier breakthroughs. If you own an aging commercial system, find out what your existing solar project may be worth before deciding whether to repair, repower, or sell.

Sources: MIT News, "Surprisingly diverse innovations led to dramatically cheaper solar panels"; TaiyangNews, "MIT study on innovations contributing to solar cost declines"