How to Write a Solar Proposal

Put the decision numbers on page one

A solar proposal gets read next to other offers: the FTC tells homeowners considering solar to get detailed bids from several companies, with the system's brand, size and performance in writing ¹. Make yours easy to compare. Page one should show:

• System size in kW DC (module count times rated watts) and the inverter's AC rating.
• Estimated first-year production in kWh and the share of annual usage it covers.
• Total price before incentives, and price per DC watt.
• Each payment option, with the cash price shown even if the customer plans to finance.
• Estimated first-year savings, labeled as an estimate.
• The date the price and the offer expire.

If a figure on page one can't be traced to a stated assumption later in the document, take it off.

Start from 12 months of usage

Size and savings both come from the customer's electricity use, so get a full year of it: one July bill can make an ordinary home look like a heavy user. Ask for 12 months of bills or the utility's usage download, and carry these into the proposal:

• Annual kWh and the monthly pattern.
• The rate schedule (tariff) name on the bill, because the savings math depends on it.
• Fixed monthly charges and any minimum bill, which production may not reduce.
• Time-of-use periods, if the rate has them.
• Hourly or 15-minute interval data, if the utility provides it, to estimate how much solar output the home will use as it's produced.

Then ask what will change. An electric vehicle, a heat pump, a pool or an addition can move annual usage a long way. Agree on which planned loads to include, and write the adjusted total and the reason on the usage page. Size for a load that never arrives and the extra output gets exported; where exports earn less than the retail rate, that output is worth less than your savings estimate assumed.

Estimate production and print the assumptions

The production estimate carries the savings, the offset and any guarantee, so present it as a calculation the customer can check. PVWatts, the calculator developed at the National Renewable Energy Laboratory (renamed the National Laboratory of the Rockies in December 2025 ²), takes the address, array size, tilt, azimuth and losses and returns estimated monthly and annual kWh. Whatever tool you use, print its inputs.

• Model each roof plane on its own, with its own tilt and azimuth, and add the results.
• Use shade measured on site. Imagery can miss young trees and winter chimney shadows. Say how shade was measured and the loss applied to each plane.
• Set the other losses for this site. Snow, dust, wiring and inverter losses vary by climate and design. If you kept a default value, say so.
• Mark what's preliminary. If you designed from imagery before the site survey, say the proposal will be reissued if the survey changes the production figure.

Example: A design puts 14 modules of 400 watts on a south-facing plane and 8 on a west-facing plane. Suppose your estimate gives the south plane 1,250 kWh per kW of DC capacity and the west plane 1,050. Production is 5.6 kW × 1,250 = 7,000 kWh plus 3.2 kW × 1,050 = 3,360 kWh, or 10,360 kWh a year. Modeling all 8.8 kW at the south plane's yield would claim 11,000 kWh, which is 640 kWh too many. These are made-up numbers; run every address on its own.

Weather varies from year to year, so the estimate describes a typical year, not a promise; say so next to the number. If you show figures for later years, state the yearly loss in panel output you assumed and its source, such as the power output terms in the module warranty.

Specify the system and the equipment

The equipment section should let another installer price the same system:

• Modules: make, model, rated watts, count and total kW DC.
• Inverter type (string, microinverters or string with optimizers), make, model and AC rating.
• Racking and the attachment method for this roof's material.
• Monitoring, and whether it needs the customer's internet connection.
• Any battery: make, model, usable kWh and the circuits it backs up.
• The electrical tie-in, and whether a main panel upgrade is needed or still to be confirmed.
• A layout drawing showing which roof planes get modules.

Attach the data sheets. Add a substitution clause: whether you may install equipment of equal or higher rating if a part is back-ordered, with notice to the customer first. List exclusions such as roof repairs, tree work, drywall and paint, with a price for any you can offer.

List each warranty on its own line

Different companies stand behind different parts of a solar system, so give each warranty its own row, with terms copied from the current warranty document.

Then answer what customers ask when something fails: who pays labor and shipping if a manufacturer's warranty doesn't, whether coverage depends on registration or approved hardware (if so, handle it yourself), whether each warranty transfers when the house is sold, and whether new penetrations could affect an existing roof warranty. Ask that last one before anyone drills.

Your workmanship warranty is the only one that depends on your company staying in business. Write it plainly, keep it the same on every proposal and have a lawyer review the wording once.

Show the price and what it buys

State the total before incentives and the price per DC watt. List adders such as a panel upgrade, roof work, trenching or a battery as separate lines so the base price stays comparable, and say what's included: design, permits and fees, interconnection paperwork, installation, inspection and monitoring setup. How to price solar installations covers building the price per watt and the adder list.

Put an expiration date on the price. Equipment costs, utility rates and incentive programs all move, so an old proposal can be wrong about cost and savings at once.

Put cash, loan, lease and PPA side by side

How the customer pays decides who owns the system and what the proposal must show:

Leases and PPAs are long commitments: the FTC notes that some last 20 years, and that because the homeowner doesn't own the system, tax credits and incentives go to the owner instead ¹. Print the full term on the same page as the monthly figure.

On loans, the financed price can differ from the cash price: if a loan program charges you a fee and you build it into the contract price, the loan customer pays more for the same system before any interest.

Example: An 8 kW DC system priced at $24,000 cash is $3.00 per DC watt. Suppose the loan program charges a fee you build in, and the financed contract price becomes $28,800. That customer pays $3.60 per watt for the same equipment and labor, before interest. Printing both prices on one page shows the $4,800 difference instead of hiding it. The numbers are illustrative.

If a loan assumes a large voluntary payment by a set month to keep the monthly payment low, show the payment with and without it, and never tie it to a federal tax credit the customer won't receive.

Lease and PPA prices come from the company that will own the system, and business owners face their own tax deadlines: IRS Notice 2025-42 explains that the section 48E credit isn't available for a solar facility placed in service after December 31, 2027 if its construction began after July 4, 2026 ³. Name the provider, print any yearly increase and don't promise its rate past the date the provider guarantees it.

Write incentive language that is accurate and conditional

Older templates still get the federal credit wrong. For homeowner-owned systems, the Residential Clean Energy Credit (section 25D) was worth 30% of qualifying costs for property installed from 2022 through 2025, and the IRS says no credit is allowed for expenditures made after December 31, 2025 ⁴. The expenditure counts as made when installation is complete, so a 2025 signature doesn't qualify a system finished in 2026 ⁵. So:

• Delete any "federal tax credit" line and any "net cost after tax credit" figure.
• Don't build loan payments, paydown dates or savings around that credit.
• If a customer asks, say it ended for systems installed after 2025 and suggest a tax professional.

Give each state, local or utility incentive its own line below the price, not subtracted from it until confirmed, with the program name, who runs it, the estimated amount, the conditions, the deadline and who receives the money.

Tip: Conditional wording can be this plain: "Estimated [program] rebate: $[amount], paid by [administrator] to [recipient] if the application is approved and funds remain. Not deducted from the contract price above."

Check each program's current rules before every proposal. Programs can close, change amounts or run out of funds, and a promised rebate that never arrives becomes your problem.

Base savings on the customer's export rules

kWh offset is not bill offset. A system that matches annual usage kWh for kWh can still leave a real bill, because savings depend on how the utility charges for power and credits exports. Net metering is one way of crediting exports, and the rules vary by state and by utility. Before you calculate savings, write down:

• The rate schedule name and its effective date.
• How exported kWh are credited: at the retail rate, at a lower export rate, or at values that change by hour or season.
• How credits carry over: month to month, to an annual true-up, or not at all.
• Fixed charges and minimum bills that remain whatever the system produces.
• Time-of-use periods. An evening peak falls after solar output drops off.
• The share of production the home will use as it's produced, and how you estimated it.
• Any yearly rate increase you assumed, plus a savings figure at no increase.

Example: Suppose a system is estimated to produce 9,000 kWh in its first year. Hourly usage data suggests the home will use 55% of that as it's produced, replacing power that costs a made-up $0.24 per kWh, and export the other 45% for a made-up credit of $0.06 per kWh. Savings: 4,950 kWh × $0.24 = $1,188, plus 4,050 kWh × $0.06 = $243, or $1,431 for the year. Valuing all 9,000 kWh at $0.24 would claim $2,160, about 51% more than these export rules support. A fixed monthly charge stays on the bill in both cases.

When a utility or regulator changes how exports are credited, re-run the savings in every open proposal before anyone signs. Find out whether the customer's export terms are set by the date of their application, approval or installation, and put that date in the timeline.

Make every savings claim one you can back up

Treat each savings figure as a claim a customer, lender or regulator may ask you to prove:

• Label it as an estimate tied to stated assumptions.
• Lead with the case that assumes no utility rate increase, then show any rate-increase case with the rate you assumed.
• Don't say the system will "eliminate" a bill that still carries fixed charges.
• Don't count unapproved incentives, and don't present the federal 25D credit as available.
• Don't suggest you're the utility or a government program, or call a lease or PPA "free solar" when the customer pays every month. The FTC tells homeowners that "free" or "no cost" solar offers are scams and that the federal government doesn't install solar systems in homes for free ¹, and it warns about sellers who claim to be from, or affiliated with, the government or the utility ⁶.
• Keep the expiration date real. The FTC warns homeowners about sellers who push for a decision on the spot or want payment in full up front ^{7 8}. A sign-today discount looks like the first, and a big payment at signing looks like the second.

When the proposal becomes the contract

Once the customer signs, the proposal's promises are contract terms. The FTC tells homeowners to look for the contractor's name, address, phone number and license number in a contract, along with estimated start and completion dates ⁸. Solar adds dates that depend on others: permit approval, inspection and the utility's permission to operate, and the system stays off until that last one. Give a realistic range for each, and say that you pull the permits and file the interconnection paperwork, listing any forms the customer must sign. The FTC counts a contractor who asks the homeowner to get the building permits among the signs of a scam ⁸.

Tie payments to milestones. The FTC advises homeowners not to pay the full amount at the start and notes that some states limit down payments ⁸. How to invoice solar installations covers milestone billing, state deposit rules and change orders when a survey turns up a panel upgrade.

Signing at the kitchen table or at a home show booth can bring in the FTC's Cooling-Off Rule, which can give the buyer until midnight of the third business day after the sale to cancel ⁹. Show that window in the proposal's timeline, hold equipment orders and permit submissions until it closes, and check your state's home solicitation rules too.

Walk through it, then follow up

Present the proposal live, in person or on a video call, starting with the assumptions rather than the savings figure, then send it with the data sheets and warranty documents attached. How to get more solar customers covers following up on open proposals and the rules for sales calls and texts.

A solar proposal checklist

1. Page one numbers, each traceable to a stated assumption.
2. Usage: 12 months of kWh, rate schedule, fixed charges, planned loads.
3. Production inputs for each roof plane, with shade method and losses.
4. Equipment, data sheets, a substitution clause and exclusions.
5. One line per warranty, with who backs it.
6. Price, price per DC watt and adders, with cash, loan, lease or PPA terms side by side.
7. Incentives as conditional lines with no federal 25D credit, and savings from the export rules.
8. Timeline to permission to operate, payment milestones and cancellation rights.