A solar design fee is your cost plus a margin. Add up design labor, review, software, outside services and a share of overhead (shared costs such as rent and admin) for one defined deliverable. Then add your margin. On a hypothetical cost of 120, a 25% markup gives 150 (a 20% margin). A 25% margin gives 160. You can quote it per design, per kW or by the hour.
SurgePV sells solar design software and publishes this guide. This page helps an installer work out a design fee and explain it to a customer. The companion design service pricing-model guide compares how a provider charges installers and EPCs.
Fee Formula and Worked Example
The formula is: fee = cost of the defined deliverable + margin. The inputs below are placeholders in currency units. Replace each one with your own task hours, loaded hourly cost and quotes. Loaded hourly cost is what an hour of work really costs you, including payroll costs on top of pay.
| Line | Calculation | Result |
|---|---|---|
| Design labor | 2.5 hours x 35 per hour | 87.50 |
| Software allocated to this design | Placeholder | 15.00 |
| Review cost | Placeholder | 17.50 |
| Cost of the deliverable | 87.50 + 15.00 + 17.50 | 120.00 |
| Fee at a 25% markup on cost | 120 x 1.25 | 150.00 |
| Margin on that fee | (150 - 120) / 150 | 20% |
| Fee at a 25% margin on price | 120 / (1 - 0.25) | 160.00 |
| Markup on that fee | (160 - 120) / 120 | 33.3% |
| Fee per kW on an 8 kW system | 150 / 8 and 160 / 8 | 18.75 and 20.00 |
| Fee per hour of labor | 150 / 2.5 and 160 / 2.5 | 60.00 and 64.00 |
A 25% markup and a 25% margin give different prices. Markup is a percentage of your cost. Margin is a percentage of the price. Decide which one your team means before you quote.
To fill in the software line, spread the license cost over the designs it supports. For example, SurgePV’s published price is USD 1,899 per user per year for one seat (pricing). Spread over a hypothetical 120 designs a year, that is 1,899 / 120 = USD 15.83 per design. For quote-based software, get the actual quote first. The PVcase price guide shows what to check with a vendor that prices by quote.
Define What the Fee Purchases
Keep these five things apart: a first sales concept, a modeled scenario, a detailed design, a package for permit submission, and engineering work by a qualified engineer that you order separately. Then state what the design is for, the inputs, the equipment it assumes, the reviews it needs and the file formats. Also state the changes it includes, what it leaves out, and how the customer accepts it. A paid layout is not ready for a permit, and no engineer has approved it, until the person responsible for review says so.
List only what the job really includes. Examples are the roof model, layout, shade assumptions, energy forecast, a first materials list, financial assumptions, drawings, and review records. Note the weather data you used and the limits of the modeled energy. A forecast is not a guarantee at any price.
Build the Cost Worksheet Before Choosing a Price
| Cost line | Source needed | Double-counting check |
|---|---|---|
| Design labor | Estimated task hours and loaded cost per hour | Do not add payroll burden again if already included |
| Review and coordination | Named tasks, roles and hours | Keep qualified external review separate if quoted separately |
| Software and data | Actual license, project-credit or data costs | Avoid charging the same subscription in both overhead and per-job allocation |
| Site information | Scope, provider quote, travel or capture basis | Identify customer-supplied and excluded work |
| Expected included changes | Defined included scope and supported effort estimate | Do not treat every later scope change as included |
| Allocated overhead | Consistent accounting basis | Distinguish allocated cost from cash incurred on this job |
| External services | Current scoped quotes and conditions | Separate taxes and pass-through treatment for qualified review |
Write down your assumptions and gaps. A neat spreadsheet does not fix a weak labor estimate. Compare your estimates with finished jobs that had a similar deliverable.
Allocate Design Labor to Signed Contracts
This example spreads design labor over the contracts that one group of designs produced. A cohort is a group of designs made in the same period. Hypothetical inputs: 60 designs in a finished cohort, 2.5 hours per design, 35 currency units of loaded labor cost per hour, and 15 signed installation contracts linked to that cohort.
- Labor: 60 × 2.5 × 35 = 5,250 currency units.
- Cohort quote-to-contract ratio: 15 ÷ 60 = 25%.
- Design labor allocated per signed contract: 5,250 ÷ 15 = 350 currency units.
This only spreads the labor. It leaves out software, reviews, other costs of winning customers, cancellations and late decisions. If a cohort signs zero contracts, you cannot work out a cost per contract. Do not mix this month’s designs with contracts signed this month that came from other designs.
Decide How the Installer Recovers Design Cost
| Route | What the buyer is told | What to assess |
|---|---|---|
| No separately charged fee | What preliminary work is included and its limits | Cost remains somewhere in the business; measure actual workload |
| Separate fixed fee (per design) | Named deliverable, amount and included changes. In the worked example, 150 per design | Scope clarity and response to changed information |
| Hourly or staged fee | Rates, tasks, reporting and agreed limits. In the worked example, 60 per labor hour | Uncertain effort and authorization of additional work |
| Capacity-based fee (per kW) | Rate, DC or AC basis and capacity source. In the worked example, 150 / 8 kW = 18.75 per kW | Capacity does not measure all design complexity |
| Installation-credit arrangement | Exact later credit conditions | Separate fee payment, refund and installation-price accounting |
Look at your own similar cohorts. Check design hours, fees collected and returned, late outcomes, complaints and signed contracts. Charging one lead source and not another does not show what the fee changed, because the two groups of buyers differ.
If design hours limit how many projects you can quote each month, the growth capacity model shows how to turn the work at each stage and each role’s capacity into a monthly limit.
Credit and Refund Terms Need Their Own Record
A fee credited against an installation price is not automatically a refundable deposit. Write down what you deliver and when payment is due. Say whether a cancellation returns money. Give the conditions for an installation credit and when it expires, if it does. Explain how changes to the scope are handled and who may use the deliverables. Get local advice on contracts, consumer law, tax and accounting.
Do not count the same credited fee twice in the total you collect for the installation. The cash you collect for design and the later installation balance should add up to the deal you agreed.
Explain the Fee Without Attacking Competing Offers
Use a short, plain script: “The fee covers [named deliverable and included review]. It excludes [specified work]. Extra changes follow [agreed process]. If you later order the installation, [exact written credit terms] apply.”
Do not say every competing free design is just a sketch. Do not claim your shade study is uniquely verified. Explain your own deliverable and its limits. Software output is not a professional certification, a utility approval or a guarantee of production.
SepiSolar’s quote page shows an hourly model in practice. SepiSolar states that it quotes on a “Not-to-Exceed” basis. For SepiSolar, that means the hours it estimates for the original scope multiplied by the engineer’s hourly rate, or the actual hours, whichever is less. It says the quote is exceeded only if the original scope or project details change. It also says residential pricing depends on size, complexity and volume. It publishes no flat rate on that page.
Copy-Ready Fee Record
- Customer, project and requested use: [identifiers]
- Deliverables and exclusions: [agreed scope]
- Source inputs and unresolved evidence: [records]
- Task cost estimates: [hours, cost basis and allocation]
- Price method and calculation: [inputs, units and assumptions]
- Included changes and additional-work route: [written terms]
- Payment, refund and installation credit: [distinct conditions]
- Qualified review and release owner: [responsibilities]
- Estimate-to-actual review: [comparable completed scope]
Check Your Design Deliverable in SurgePV
Bring your cost worksheet to a guided demo. You will see which design outputs SurgePV produces and what manual review is still left. Subscription prices are on the pricing page.
Book a Free DemoExplore Solar DesigningFrequently Asked Questions
How much should I charge for a solar design?
Define the deliverable. Add up labor, review, software, outside services and overhead, and count each cost only once. Then add your margin. On a hypothetical cost of 120 currency units, a 25% markup gives 150 and a 25% margin gives 160. Use your own costs, not a market average.
How do I price a solar design per kW?
Work out the fee for the deliverable first. Then divide it by the system size in kW. A hypothetical 150 currency-unit fee on an 8 kW system is 18.75 per kW. Per-kW pricing hides how hard a job is, so keep a rule for difficult roofs and extra scope.
Should design be free or paid?
Either can be a sound business choice. A design with no separate fee still costs labor, so measure that cost. Compare your own cohorts. Look at hours spent, fees collected and returned, and signed contracts.
Is a design fee credit the same as a refund?
No. A credit against a later installation price and money returned on cancellation have different conditions and different accounting effects. Put each in writing and get local advice.
Does paying for design make it permit-ready?
No. What the design is for, its scope, the reviews by qualified people and the authority’s decision decide whether it is ready for a permit. A paid layout or a generated report is not an approval.
Sources
Primary research and reference material used for this desk-research article.
Where this fits
This article is part of SurgePV's Solar Business & Operations hub, which works through the topic from first principles to the decisions a project team actually has to make.
