Solar costs
Solar Cost Per Watt, Explained
The standard way to compare solar quotes, and the most commonly manipulated number in a solar proposal.
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Cost per watt is the total system price divided by the system size in watts. A $21,000 system at 7,000 watts is $3.00 per watt. It exists so that quotes for different sized systems can be compared at all. It is only meaningful when both quotes are computed the same way, and a surprising number of them are not.
In short
- Total price ÷ system size in watts. That is the whole formula.
- Always compare gross — before incentives. Net figures describe your tax position, not the quote.
- Keep the battery out of it. Storage is priced per kilowatt-hour, not per watt.
- Small systems have a higher cost per watt for structural reasons, not because someone is overcharging.
- We publish no national average, on purpose. It anchors you to a number that has nothing to do with your roof.
Why we do not publish a national average
Almost every solar site leads with one. We think it does more harm than good, for three reasons.
- It anchors the wrong conversation. A homeowner who arrives believing the answer is $2.80 spends the meeting arguing toward that number instead of asking what is in the scope.
- It hides the variables that actually moved your price. Two quotes can differ by a dollar a watt entirely legitimately — a service panel upgrade, a tile roof, three roof planes instead of one.
- It is not comparable to your quote unless you know how it was built. Gross or net of incentives? Cash or financed? Battery included? Published averages frequently do not say.
So the number we would have to publish to be useful is one we do not hold, and the number we could publish would mislead. What follows is the method instead.
Every dollar figure on this page is a worked example, not a market price. The numbers exist to show the arithmetic — divide this by that — and they are chosen because they divide cleanly. They are not a benchmark, not an average, and not what a system should cost where you live. We hold no installed-price dataset and publish no price guidance; see why below.
Computing it from a real quote
- Find the system size in watts. Quotes usually state kilowatts. A 7.2 kW system is 7,200 watts. Some state DC and AC ratings; use DC, and use the same one across every quote.
- Find the gross price. Before any federal, state or utility incentive, and before financing.
- Remove anything that is not generation. Battery, EV charger, roof work, tree removal, service panel upgrade. Price those separately.
- Divide. Gross generation price ÷ watts.
Our proposal analyzer does this from a real quote and shows what each line item is doing.
Four ways the figure gets distorted
None of these are necessarily dishonest. All of them make one quote look better than another for reasons that have nothing to do with the system.
1. Quoting net of incentives
A $21,000 system at 7,000 watts is $3.00/W. Subtract any incentive before dividing and the same system quotes lower — a $4,200 incentive makes it $2.40/W. Both describe the same hardware. Only the gross figure describes what the company is charging.
A net figure also assumes you can actually use the incentive, and a tax credit is worth nothing to a household with no liability to offset against.
Be careful with older quotes and older articles. Section 25D, the 30% residential clean energy credit, was terminated for expenditures made after 31 December 2025. A proposal or a web page that nets 30% off the price for an owner-occupier may be working from rules that no longer apply. Third-party-owned systems sit under a different credit on a different timetable.
What changed with Section 25D and why a lease still gets a credit and you do not set out the statute and the dates.
2. The dealer fee inside a financed price
Financed solar frequently carries a fee paid to the lender, built into the amount financed and rarely shown as its own line. The advertised interest rate looks attractive; the effective rate on the cash price is higher.
This inflates cost per watt against a cash quote for an identical system — or, if the comparison quote also has one and neither is disclosed, hides the difference entirely. Our dealer fee calculator solves for the rate you are actually paying. Solar financing compared covers all four structures, and what "zero down" really means covers the pattern.
3. Bundling the battery
Storage is priced per kilowatt-hour of capacity. Generation is priced per watt. Adding a battery's cost to the numerator while leaving the denominator as panel watts produces a figure that means nothing and is always high.
4. Using the AC rating for size
A system's DC panel rating is higher than its AC inverter rating. Dividing by the smaller AC number produces a higher cost per watt for the same system. Legitimate either way — but only if both quotes use the same basis.
Why small systems cost more per watt
Smaller systems carry a higher price per watt for structural reasons rather than suspicious ones, and the gap catches people comparing a townhome quote against a neighbour's detached-home figure.
- Scales with size: modules, racking, some inverter capacity.
- Does not scale: design, permitting, the interconnection application, mobilising a crew, commissioning, and travel.
Those fixed costs are similar whether the array is six panels or twenty-six. Spread over fewer watts, they raise the per-watt figure. A small system is not badly priced for being small. Cost by system size has the sizing data.
What legitimately moves your cost per watt
| Factor | Direction and why |
|---|---|
| System size | Larger systems spread fixed costs further, lowering the figure. |
| Roof complexity | Multiple planes, steep pitch, tile or slate all add labour for the same watts. |
| Equipment choice | Microinverters and optimisers cost more than a string inverter, and earn it on shaded or complex roofs. |
| Electrical work | A service panel upgrade or a long conduit run adds cost without adding watts. |
| Local labour rates | Real and substantial, and nothing to do with the equipment. |
| Permitting and interconnection | Set by your jurisdiction and utility, not the installer. Fixed, so they hit small systems hardest. |
| Self-perform or subcontract | Changes the cost structure, and changes who owes you a workmanship warranty. |
How to compare quotes properly
- Get all quotes on the same system size basis — DC watts throughout.
- Use gross price, before incentives and before financing.
- Strip non-generation items into a separate column: battery, charger, roof work, panel upgrade.
- Ask each company for the dealer fee, if the price is financed, as a number.
- Then compare — and when one is materially cheaper, ask what is different rather than assuming it is a better deal. Equipment, inverter architecture, warranty length and who performs the work are the usual answers.
A quote that is cheaper because it uses a string inverter on a shaded roof is not cheaper. It is a different, worse system at a lower price.
Common questions
What is cost per watt in solar?
Total system price divided by system size in watts. A $21,000 system at 7,000 watts is $3.00 per watt. It exists so systems of different sizes can be compared on a common basis, because a bigger system costing more tells you nothing on its own.
What is a good cost per watt?
There is no national figure that is meaningful for your house, and we do not publish one. It varies with system size, equipment, roof complexity, electrical work, local labour rates and whether the price is before or after incentives. The useful comparison is between real quotes for your own roof, computed the same way.
Should I compare cost per watt before or after incentives?
Before. Gross cost per watt describes the system and the company. Net cost per watt describes your tax position, which is not a property of the quote at all and is not comparable between households. Ask for the gross figure and compare on that.
Why is my cost per watt higher than the figures I see online?
Common reasons: your system is small, so fixed costs spread over fewer watts; your roof is complex, tile or steep; you need a service panel upgrade; the quoted figure you are comparing against was net of incentives while yours is gross; or the online figure includes a dealer fee and yours does not, or vice versa.
Does cost per watt include the battery?
It should not. A battery is priced per kilowatt-hour of storage, not per watt of generation. Folding it into the same figure makes a quote look expensive per watt and makes comparison impossible. Ask for them separated.
Next
Run a real proposal through the proposal analyzer, check the financing with the dealer fee calculator, and see what size systems people actually install. When you are comparing companies rather than numbers, how we vet sets out what to check.
HyreSolar does not install or finance solar systems. Prices vary by location, utility, system design, equipment, incentives and individual circumstances, and nothing here is a quote or an estimate for your property.