A homeowner with three solar quotes in hand has an 8 kW system from one company, a 9.6 kW system from another and a battery package from the third. The totals cannot be compared. The price per watt can, which is why buyers divide and why your quote should show it. That number has to come from your own costs, though, not from someone else’s quote, and then be checked against what the national data says.
What the national numbers say
Two sources are worth knowing, and they measure different things.
Why the gap? Berkeley Lab’s 2024 summary explains that its medians run higher than other benchmarks, which sit closer to its 20th percentile, partly because prices reported for loan-financed systems likely include dealer fees, “adding anywhere from 5-50% to the total up-front price paid by the customer.” Its reported prices can also include ancillary work such as electrical or roofing.
The spread between installers is wide. Among the top 100 residential installers in 2025, median prices ran from $2.4 to $6.3 per watt. Roughly 60% had medians below $4, almost 25% below $3, and about 10% above $5. Even one installer’s own jobs typically spread across a band $1 to $2 per watt wide. There is no single “right” price per watt; there is yours, and where it falls in that spread.
The typical job is bigger than it was: the median residential system was 7.7 kW in 2025, with most between roughly 5 and 12 kW.
Build your own price per watt
Berkeley Lab puts soft costs and other balance-of-system costs at roughly 80% of the installed price of residential systems in 2025. Soft costs, in its definition, are customer acquisition, installation labor, permitting and interconnection, financing fees for some loans, taxes and profit. The panels are the small part. SEIA’s average module price for the distributed segment was $0.37 per watt in the second quarter of 2026, after a 16% drop over the year.
So build the number from four groups: hardware per watt, crew labor per watt, the fixed costs of every job, and overhead and sales. Then set the margin. Say an installer’s own numbers for a roof-mounted job look like this:
| Cost line (an example) | 8 kW job | 5 kW job |
|---|---|---|
| Modules at $0.37 per watt | $2,960 | $1,850 |
| Inverters, racking, wire at $0.55 per watt | $4,400 | $2,750 |
| Crew labor at $0.40 per watt | $3,200 | $2,000 |
| Design, permit, interconnection (fixed per job) | $1,500 | $1,500 |
| Sales and overhead at $0.70 per watt | $5,600 | $3,500 |
| Cost | $17,660 | $11,600 |
| Price at a 25% margin | $23,547 | $15,467 |
| Price per watt | $2.94 | $3.09 |
The fixed $1,500 is why the small job costs more per watt. Price per watt is a quoting shortcut, not a cost model: keep the fixed costs per job in the spreadsheet behind it, or the small systems lose money. The margin line divides cost by 0.75; if you are used to adding a markup instead, Markup vs. Margin shows why the two give different prices.
What moves the price per watt
Berkeley Lab ran a regression on homeowner-owned residential systems installed in 2023 to separate the drivers. Its findings are a useful checklist for your own tiers:
The roof is your own call. A steep pitch, tile, a second story or a split array across several faces takes more crew hours; put those hours in the labor line for that job rather than raising every customer’s price per watt.
Adders go on their own lines
Some work belongs to the house, not the array. Quote it separately, so the price per watt stays comparable and the homeowner sees why this job costs more than a neighbor’s:
Keeping adders out also keeps your comparison honest: Berkeley Lab’s reported prices can include electrical or roofing work, so your bare price per watt may look lower than its median for that reason alone.
The cash price and the financed price
Berkeley Lab found loan-financed residential systems priced well above cash sales: in 2024 the medians were $4.7 per watt with a loan and $3.5 for cash, a gap that grew from $0.6 per watt in 2017 to $1.2 in 2024, “due partly to the loan fees rolled into the up-front price.”
The CFPB’s 2024 Issue Spotlight on solar financing describes those fees: “Hidden fees typically range from between 10 to 30 percent of the cash price but can exceed 50 percent.” Its example is a system with a $30,000 cash price and a $9,000 fee, and it notes that lenders typically do not include such fees in the total cost of credit they show the borrower. Three habits keep your quotes clean:
- Show the cash price on every quote, and the financed price beside it, with the lender’s fee as a visible line.
- Quote the price per watt on the cash price, so the number you compare to the national data means the same thing.
- Before you advertise a monthly payment, read Advertising Financing: Regulation Z’s Triggering Terms.
One line has to go from older quote templates entirely. The CFPB described as potentially misleading the common practice of showing the actual loan in small, light type and a “net system cost,” the loan minus a presumed 30% tax benefit, in large, bright type. That credit is now gone for homeowner-owned systems: the IRS says the Residential Clean Energy Credit “is not available for any property placed in service after December 31, 2025.” SEIA’s report describes the residential market softening as it adjusts to the credit’s end. The Home Energy Tax Credits Ended covers what you may still say about incentives in a sale.
Check it twice a year
Module prices moved 16% in a year and tariffs keep changing, so rerun the table with fresh supplier quotes and your last six months of crew hours each spring and fall. Then compare your price per watt with Berkeley Lab’s spread and SEIA’s average, and decide on purpose where you want to sit.
If homeowners ask you for a rough number before they will book a site visit, NapkinPrice™ puts an instant price range from your own pricing rules on your website and sends you the homeowner’s answers with the lead, so the range they see comes from the same rates as your quote. The page for solar installers shows how it handles a solar job, from kilowatts to panel tier, inverter and roof.
General information, not legal or tax advice. Rules change and vary by state; check with the agency named above or a professional for your situation.