Solar is cheaper than nuclear to build and, in most analyses, cheaper per unit of electricity produced. The gap has widened dramatically over the past decade as solar costs have plummeted while nuclear construction costs have climbed. But the full picture is more nuanced than a single price tag, because these two energy sources behave very differently on the grid.
Upfront Construction Costs
The cost to build a power plant before it generates a single watt of electricity is called the “overnight capital cost,” and this is where the difference is starkest. Average U.S. solar construction costs came in at $1,588 per kilowatt in 2022, according to the EIA. New nuclear plants, by contrast, typically cost between $6,000 and $12,000 per kilowatt depending on the design and location. The two most recent U.S. nuclear builds illustrate the problem: the Vogtle expansion in Georgia came online roughly seven years late and billions over its original budget, with final costs estimated above $30 billion for about 2.2 gigawatts of capacity.
Solar projects, on the other hand, can go from permitting to operation in one to three years. That shorter timeline reduces financing costs and the risk of budget overruns. A utility-scale solar farm can be built in phases, adding capacity incrementally, while a nuclear reactor is an all-or-nothing investment that ties up capital for a decade or more before generating revenue.
How LCOE Compares
The standard way to compare energy costs across technologies is the levelized cost of energy, or LCOE. It rolls together construction, fuel, maintenance, and financing into a single price per megawatt-hour over a plant’s lifetime. Most recent estimates put utility-scale solar between $30 and $50 per megawatt-hour, while new nuclear lands between $90 and $150 per megawatt-hour. By this measure, solar is roughly two to four times cheaper.
These numbers come with context, though. LCOE treats every megawatt-hour as equal regardless of when it’s produced. A megawatt-hour of solar generated at noon on a sunny day is less valuable to the grid than a megawatt-hour of nuclear produced at 7 p.m. on a winter evening when demand peaks and the sun has set. Some analysts prefer “value-adjusted” LCOE, which accounts for when and how reliably power is delivered. Nuclear looks better under that lens, though it still rarely beats solar on pure cost.
The Capacity Factor Gap
One reason nuclear’s operating economics are stronger than its construction costs suggest is its capacity factor, the percentage of time a plant runs at full power. Nuclear plants operated at a capacity factor above 92% in 2024, the highest of any energy source. Solar panels, by comparison, have a capacity factor of about 23.4%. That means a 1,000-megawatt nuclear plant produces roughly four times more electricity per year than a 1,000-megawatt solar installation.
This matters for land use and grid planning. To match the annual output of a single large nuclear reactor, you’d need a solar installation covering thousands of acres plus a way to store or supplement that energy when the sun isn’t shining. The storage question is critical: pairing solar with battery storage adds $20 to $40 per megawatt-hour to the total system cost, narrowing the gap with nuclear, especially for grids that need reliable power around the clock.
Operating and Maintenance Costs
Once built, solar farms are relatively cheap to maintain. Fixed operations and maintenance costs for utility-scale solar run about $22 to $24 per kilowatt per year, covering panel cleaning, inverter replacement, vegetation management, and monitoring. Solar has no fuel costs at all.
Nuclear plants carry higher ongoing expenses. They require specialized staff, extensive safety systems, regular refueling outages, and security infrastructure mandated by federal regulators. Industry data puts nuclear operating costs in the range of $25 to $35 per megawatt-hour, which includes fuel. Uranium fuel itself is cheap relative to fossil fuels, but the human and regulatory overhead of running a reactor is substantial. Nuclear plants also face significant decommissioning costs at the end of their lives, typically hundreds of millions to over a billion dollars per reactor, though these are funded gradually over the plant’s operating life.
Tax Credits and Subsidies
Both technologies receive federal support under the Inflation Reduction Act, but the structure differs. Solar projects can claim an investment tax credit of up to 30% of qualifying construction costs, with additional bonuses of 10 to 20 percentage points for projects in low-income communities or energy communities with displaced fossil fuel workers. Residential rooftop solar gets a similar 30% credit through at least 2034.
Existing nuclear plants qualify for a zero-emission nuclear power production credit (known as 45U), designed mainly to keep operating reactors from shutting down prematurely rather than to incentivize new builds. New nuclear can access clean energy production credits, but because the per-kilowatt construction cost is so much higher, the credits offset a smaller proportion of total project cost compared to solar. In practice, subsidies have accelerated solar deployment far more than nuclear deployment in recent years.
Where Nuclear Still Has an Edge
Cost per megawatt-hour isn’t the only factor utilities and grid planners weigh. Nuclear provides what’s called “firm” power: it runs day and night, in any weather, for 18 to 24 months between refueling outages. That reliability has real value in a grid that increasingly depends on variable renewables. Regions with limited land, weak solar resources, or very high baseload demand may find nuclear more practical even at a higher sticker price.
Nuclear plants also last a long time. Most U.S. reactors are licensed for 60 years, with some applying for extensions to 80 years. Solar panels degrade over time, losing roughly 0.5% of their output per year, and typically carry 25- to 30-year warranties. Over a multi-decade horizon, a nuclear plant’s high upfront cost gets spread across more years of production, improving its lifetime economics relative to shorter-lived solar installations.
Small modular reactors, a newer class of nuclear technology, aim to bring construction costs down by standardizing designs and building components in factories. None are operating commercially in the U.S. yet, so their real-world costs remain unproven. If they deliver on cost targets, the nuclear-solar comparison could shift, but that’s a significant “if” given nuclear’s long history of cost overruns.
The Bottom Line on Cost
For generating electricity at the lowest cost per megawatt-hour today, solar wins clearly. It’s cheaper to build, faster to deploy, and costs less to maintain. But electricity grids don’t just need cheap energy; they need reliable energy at all hours. When you factor in the cost of batteries or backup generation to make solar available around the clock, the gap narrows. Nuclear remains more expensive on most measures, but it delivers something solar alone cannot: constant, weather-independent power from a small footprint. The cheapest grid of the future will likely use both, with solar doing the heavy lifting on cost and nuclear (or storage) filling the gaps.