How much do solar panels cost? Price a quote in cost per watt

The short answer: one division, two reference lines

Take the gross price on the quote and divide it by the system size in watts. A system described as 8 kW is 8,000 watts, so a $23,600 gross price is $2.95 per watt. That $2.95 figure is not chosen at random: it is the U.S. Department of Energy's Q1 2025 residential benchmark, $2.95 per watt DC (modeled market price for an 8 kW system, 2024 dollars, checked October 30, 2026), which this site uses as its comparison line. A quote at the benchmark is priced like the benchmark system. A quote above it owes you an explanation in equipment, roof difficulty, or included work, and a quote below it deserves the same question in reverse.

A second, independent reference line keeps the first one honest. The Lawrence Berkeley National Laboratory Tracking the Sun distributions, republished in the Department of Energy contract guide with data through 2023, put the national median installed residential price at $4.20 per watt, with the middle range running from $3.20 at the 20th percentile to $5.50 at the 80th. The state medians listed there run from $3.20 to $5.20 per watt. Those are 2023 figures, not today's prices, and they are medians across system sizes, so treat them as a dated map of how wide the spread legitimately runs, not as a target. The worksheet below is how you locate your own quote on that map.

Step one: pin down the gross price and what it bundles

The gross price is the full contract price before any incentive. The Department of Energy notes that a contract's financial summary shows the cost of materials, labor, and installation, and may also include the costs of permits and inspections, which can be a significant part of the total. So the first worksheet question is not the number itself but its contents: are permitting and inspection inside it, is the electrical work inside it, and what sits outside it as a possible extra, such as roof repair, a main panel upgrade, or trenching for a ground run?

Add-ons must leave the solar price before any division happens. A battery, a roof replacement, or a panel upgrade bundled into one contract total inflates the apparent cost per watt of the solar system itself. Ask for the solar system priced on its own line, with each add-on on its own line. A quote that cannot be unbundled cannot be compared, and an installer who will not unbundle it has told you something worth knowing before you sign.

Step two: subtract only incentives you have verified

Net price is gross price minus incentives, and this is the line where quotes most often flatter themselves. One change matters before any other: there is no federal residential solar tax credit in any figure on this page, because that credit ended for systems placed in service after 2025. If a quote's net price quietly assumes a federal credit, the net price is wrong for a system installed now. This site's record of the credit's status is on the solar tax credit status page in the payback section; read it before you let any seller do credit math at your kitchen table. Whether a full-price system still pays back is worked in is solar still worth it in 2026.

State, utility, and local incentives still exist in many places, and they belong in the worksheet only after you have verified them yourself in DSIRE or on the utility's own tariff pages, for your address and your install date. Until then, carry the incentive line as unknown and compare quotes on gross price per watt, which no programme rule can move. The worked example below shows the arithmetic with a round hypothetical incentive so you can see exactly where your verified figure will land when you have it.

Step three: cost per first-year kilowatt-hour, the second unit

Cost per watt compares prices for the same size. Cost per first-year kilowatt-hour compares prices for the same energy, which is what you are actually buying. Divide the net price by the production estimate's first-year kilowatt-hours. Two quotes can tie on cost per watt and separate here, because one roof plan, panel orientation, or shade assumption produces more energy per watt than the other. A cheaper system that produces less can cost more per unit of energy than a pricier system that produces more.

The production figure you divide by is an estimate, and it deserves its own reading before you trust the result. The companion guide on how to read a solar production estimate walks through the inputs, the losses, and the guarantee language behind that number. Use the same discipline here: if two installers model the same roof and their first-year estimates differ widely, the cost-per-kilowatt-hour gap between their quotes is partly a modelling gap, and the inputs, not the totals, are where the argument should happen.

Why two quotes for the same roof land apart

Legitimate spread comes from four places. Size: fixed costs such as permitting and design spread over more watts on a larger system, so cost per watt usually falls as systems grow, one reason the Tracking the Sun medians are stated across sizes. Equipment: premium panels, microinverters instead of a string inverter, and monitoring hardware all price differently, and for imported cells and modules entered on or after December 4, 2026 the price can include the Section 232 import price floors. Roof reality: steep, high, shaded, or structurally complicated roofs cost more to work on. And scope: one quote may carry the main panel upgrade and permit fees inside the total while the other lists them as extras, which is why step one comes before any division.

Illegitimate spread is easier to spot once the worksheet exists. A quote sold on a monthly payment instead of a price, a net price built on incentives nobody verified, a production estimate far above what the same roof gets from every other modeller, or a cost per watt far from the benchmark with no equipment or roof explanation: each is a specific question to put to the installer, in writing, before the contract. The quote red flags guide works through those sales patterns in full. The published benchmarks disagree for reasons of their own, which the price-per-watt reconciliation sorts out before you set a quote against them.

Inside the $2.95: the system the benchmark actually models

A comparison line is only useful if you know what it describes, and the Department of Energy publishes the model behind its benchmark. The Q1 2025 PV System Cost Model files, released by the National Laboratory of the Rockies (formerly NREL) on November 13, 2025 and linked from the benchmark page, describe the residential case in detail. The system is 8 kW DC on a pitched roof, built from twenty 400 watt modules wired as two strings of ten, with parallel-to-roof racking, flashed roof attachments, rails and clamps. The inverters are domestically assembled 350 watt microinverters, and the inverter load ratio is 1.14, meaning 1.14 watts of panels for every watt of inverter capacity. The installer is modelled as a small regional company. Two exclusions matter more than anything else on the list: the fieldwork line states that an electrical service upgrade and roof repair are excluded.

That description turns the benchmark from an abstract number into a checklist. A quote for a similar system on an ordinary composition shingle roof, with no panel upgrade and no roof work, is the closest match the benchmark has, and it is fair to expect it to land near the line. A quote that adds a new service panel, a reroof, a ground mount, tile hooks or a battery is pricing work the model leaves out, so the extra cost is expected, but each piece should be visible on its own line. A quote using a single string inverter instead of microinverters is a different equipment choice from the one modelled; the trade-offs between the two architectures are laid out in the microinverter and string inverter comparison.

The model also states its own uncertainty. Beside the point values, the model file prints a benchmark range for the PV-only residential system: $2,319 to $3,248 per kW for the modelled market price, about $2.32 to $3.25 per watt, and about $2.38 to $3.19 per watt for the minimum sustainable price. The $2.95 headline is the central value for the 8 kW reference case, and the range is a reminder that even the model does not claim to know the price to the cent. The model covers systems from 4 to 16 kW, and how size alone moves the price is the next section's subject.

Why a small system costs more per watt: the fixed costs, itemised

Some of a solar project's cost scales with the number of panels: modules, racking, wire and the hours spent bolting them down. Some does not scale at all. A permit costs roughly the same for 5 kW as for 12 kW, a salesperson's time is spent per household rather than per panel, and a monitoring gateway is one box whatever sits behind it. The benchmark model lists these fixed items one by one, and adding them up shows why cost per watt falls as systems grow even when nothing else changes; which of them an owner who installs the system still pays is split out in the guide to installing solar yourself.

Spread that $8,733 over different system sizes and the effect is plain. On a 4 kW system it is about $2.18 of every watt; on 6 kW, $1.46; on the 8 kW reference system, $1.09; on 10 kW, $0.87; on 12 kW, $0.73; on 16 kW, $0.55. Those are model inputs before profit and tax are layered on top, so the real per-watt gap between a small and a large system is a little wider than the arithmetic shows. The practical reading: a 4 kW system carries about $1.09 per watt more of these fixed inputs than the 8 kW reference system, so a small-system quote above the benchmark may simply be carrying the same fixed costs as a large one, while a 12 kW quote at the same price per watt has less excuse.

Real sales data add a caution. Lawrence Berkeley National Laboratory's 2026 data update, covering systems installed in 2025, found that economies of scale were not especially evident among residential systems that year, noting that other factors may dominate the visual trend even though earlier statistical analyses had shown clear size effects. The fixed costs are real; in actual markets, differences between installers and regions are often larger than the size effect. So use the size argument as one legitimate explanation an installer can give, not as an automatic pass for any small-system price. Sizing the system to your consumption first, as the panel sizing guide works through, keeps the size from being chosen to flatter the per-watt figure.

Where real installers price: the 2025 spread

The benchmark is a model. Berkeley Lab's Tracking the Sun programme counts what owners actually paid, and its 2026 data update gives the clearest recent picture of how widely installers' prices sit. Across the 100 largest residential installers in its 2025 data, median prices ranged from about $2.4 to $6.3 per watt, ignoring outliers at either end. Roughly 60 percent of those installers had median prices below $4 per watt, almost 25 percent were below $3, and about 10 percent were above $5. Within a single installer's own projects, the 20th to 80th percentile band typically spanned $1 to $2 per watt.

Three more findings from the same update change how a quote should be read. Prices for host-owned residential systems fell by $0.5 per watt year over year in inflation-adjusted terms, with larger declines for cash purchases, so a price that was typical two years ago may now be high. Loan-financed systems were considerably more expensive than cash purchases, which the lab ties in part to loan origination fees rolled into the up-front price; that is the dealer fee problem described in the guide to solar loan dealer fees. And soft costs together with other balance-of-system costs made up roughly 80 percent of the median installed price in 2025. The panels are the smaller part of what you are paying for; the labour, permitting, sales and overhead behind them are the larger part.

Two quotes, one roof: a worked comparison

The worksheet earns its keep when two quotes disagree, so here is a labelled illustration with every input stated. None of these figures describes a real installer; they show how the two units can point in different directions.

Quote A proposes 7.2 kW DC on the south roof plane only, at a gross price of $22,680, with a first-year production estimate of 10,080 kWh (1,400 kWh per kW). Quote B proposes 8.8 kW DC across the south and east planes, at $25,960, with an estimate of 11,264 kWh (1,280 kWh per kW, lower because the east plane catches less sun). On cost per watt, A is $3.15 and B is $2.95, so B looks cheaper and sits exactly on the benchmark line. On cost per first-year kilowatt-hour, A is $2.25 and B is $2.30, so A delivers each unit of energy for less. B's extra 1.6 kW buys 1,184 more kilowatt-hours a year for $3,280 more, which is $2.77 per added first-year kilowatt-hour, well above either quote's average.

Neither quote is wrong. The comparison simply asks a sharper question than either total could: is the east plane worth adding at that price? The answer depends on how much of your consumption the smaller system already covers and what your utility pays for exports, which is why your export rule belongs in the decision before you choose between them. If the extra production would mostly be exported at a low credit, the marginal $2.77 buys less than it appears to. If it replaces electricity you would otherwise buy at the full retail rate, it may be worth it.

When the cost-per-watt test misleads

The division is simple, but a few situations can make the result misleading if you apply it without checking what went into it.

• AC watts in place of DC watts. The benchmark is per watt DC, the panels' nameplate. A quote that states the system's size in inverter AC watts divides by a smaller number and shows a higher cost per watt than the same system measured in DC. With the model's 1.14 load ratio, the difference is about 14 percent. Confirm which unit the size is in before comparing.
• A loan price in place of a cash price. If the financed price includes a dealer fee, the cost per watt measures the loan as much as the system. Ask for the cash price of the same contract and run the division on that.
• Leases and PPAs. There is no purchase price to divide. Compare the lease's total payments, or the PPA's price per kilowatt-hour, against what owning would cost, using the lease, loan and PPA comparison.
• Roof types the model does not cover. The benchmark assumes a pitched roof with standard flashed attachments. Clay or concrete tile adds hook replacement and breakage risk, priced in the tile roof guide, and a ground mount replaces roof racking with foundations and trenching.
• Prices that change after the site survey. A low initial price that grows after the survey is the pattern in the guide to adders and change orders. Run the division again on the final contract price, not the opening one.
• Expansions. Adding panels to an existing system carries a full set of fixed costs for only a few kilowatts, so its cost per watt is usually well above a new system's. Judge an expansion by the cost of each added kilowatt-hour instead.

Put the worksheet to work on your quotes

Run each quote through the same five lines: gross price, solar-only after unbundling, verified incentives, net price, then cost per watt and cost per first-year kilowatt-hour. Quotes reduced to the same two units can be lined up honestly even when the proposed sizes differ. This site's Quote Comparison tool holds competing quotes side by side in exactly these terms, and the estimator prices a single quote against the benchmark with your bill and roof figures. Price the system first, then judge financing, leases, and batteries against that priced baseline, never instead of it.