What Belongs in a Solar Proposal? A Practical Installer Checklist

A solar proposal has to do several jobs at once. It must explain a technical system, show how that system affects the customer’s energy use, present the price and payment choices, define what the contractor will deliver, and give both parties a reliable record of what was accepted.

That is more than a sales presentation. A strong proposal becomes the bridge between the design, the customer’s decision, and the work your operations team must eventually complete.

Use this checklist to review the substance of a residential or commercial solar proposal before it reaches the customer. Not every project needs the same number of pages, but every important assumption should be understandable, traceable, and consistent with the system being sold.

1. Make the project identity unmistakable

Start with the information that tells everyone which project and version they are reviewing.

• Customer or organization name.
• Installation address and billing address when different.
• Proposal number, version, and preparation date.
• Proposal expiry or price-validity date.
• Primary salesperson or project contact.
• Contractor’s legal name, business address, phone number, email, and licensing information where applicable.
• The selected system option when several options were prepared.

Version information matters because solar proposals change. Equipment availability, customer preferences, roof conditions, financing, and incentives can all produce revisions. The signed document should make the accepted version clear.

2. Show the system the customer is actually buying

The proposal should describe the final system, not a generic product package.

• Number, manufacturer, and model of modules.
• Total DC system capacity.
• Inverter or microinverter manufacturer, model, and quantity.
• Battery manufacturer, model, usable capacity, power rating, and quantity when included.
• Relevant interconnection, rapid-shutdown, monitoring, mounting, or balance-of-system equipment.
• Array location, orientation, tilt, and mounting type.
• A site plan, roof layout, or clear system visualization.
• Estimated annual production.
• Any system options the customer is comparing.

When products may be substituted, explain the substitution rule. “Equivalent equipment” should not become permission to install something materially different without a defined standard or customer approval.

The proposal should remain connected to the current design. If the module count, inverter, battery, layout, or system capacity changes, the commercial document must change with it.

3. Explain the energy baseline

Savings and production claims depend on the customer’s starting point. Show the inputs used to model that starting point.

• Annual electricity consumption.
• The period covered by the utility data.
• Monthly consumption profile when available.
• Utility and applicable rate structure.
• Energy charges, demand charges, fixed charges, taxes, and other components included in the model.
• Current import and export compensation rules.
• Expected changes such as an electric vehicle, heat pump, business expansion, or new equipment.

If consumption was estimated from incomplete information, say so. A proposal based on one bill, a customer recollection, or an assumed usage profile should not look as certain as one built from complete interval or monthly data.

4. Make production assumptions visible

An annual production number is only useful when the customer and installer can understand what supports it.

• Weather or irradiance source.
• Array tilt and azimuth.
• Shading assumptions.
• System losses.
• Module and inverter performance data.
• Any clipping or equipment limitations considered.
• First-year production estimate.
• Expected degradation when long-term results are shown.
• The software or method used to prepare the estimate when relevant.

A proposal does not need to reproduce an engineering report, but it should avoid presenting modeled production as a guaranteed outcome unless the contract includes an explicit production guarantee with clearly defined terms.

5. Separate production, consumption, and utility savings

These numbers answer different questions:

• Production is the electricity the solar system is expected to generate.
• Consumption is the electricity the customer uses.
• Self-consumption is solar energy used at the site when it is produced.
• Grid import is electricity purchased from the utility.
• Export is excess solar energy sent to the grid.
• Utility savings depend on how imports, exports, credits, demand, and fixed charges are treated.

Do not collapse these into a single “offset” percentage without explaining what it represents. A system can produce as much energy as the customer uses annually while still importing and exporting significant amounts at different times.

6. Present the complete price

The customer should be able to identify the real contract price without reverse-engineering the proposal.

• Base system price.
• Taxes.
• Optional equipment or upgrades.
• Discounts.
• Incentives or rebates and whether they reduce the invoice or arrive later.
• Deposit and payment schedule.
• Allowances and items priced after inspection.
• Potential change-order items.
• Total cash price.

If the project contains an assumed tax credit, rebate, grant, or performance incentive, identify who is responsible for eligibility and application. Do not present a conditional benefit as though it were a guaranteed discount from the contractor.

7. Make financing comparable to cash

Financing can make a proposal easier to buy and harder to understand. Present enough information for the customer to compare the financed offer with the cash price.

• Cash price.
• Financed amount.
• Down payment.
• Interest rate.
• Term and amortization.
• Payment frequency and amount.
• Any promotional period.
• The rate or payment after a promotional period ends.
• Dealer fees, finance charges, administration fees, or other costs included in the price or loan.
• Total of payments when available.
• Prepayment terms and penalties.
• Security interest, lien, or property-related obligation when applicable.

A monthly payment alone is not a complete financing disclosure. The proposal should not make a higher financed price look identical to a lower cash price simply because the customer sees only the payment.

8. Explain batteries in customer terms

When storage is included, connect the battery specification to the outcome the customer expects.

• Usable energy capacity.
• Continuous and peak power.
• Whole-home, partial-home, or selected-load backup.
• Which loads are expected to remain available during an outage.
• Expected seasonal backup range and the assumptions behind it.
• Whether solar can recharge the battery during an outage.
• Operating reserve and minimum state of charge.
• Time-of-use, self-consumption, demand reduction, or backup operating mode.
• Generator interaction when applicable.
• Equipment required for isolation and backup operation.

A statement such as “one day of backup” is rarely meaningful without the backed-up load, weather, solar availability, and operating reserve.

Powerlily’s battery analysis tools model storage against the project’s solar production and customer usage so the proposal can explain the result rather than relying on a generic runtime claim.

9. Define the installation scope

The scope should help the customer understand what the price includes and help operations deliver the same project sales promised.

• Design and engineering responsibilities.
• Permit and interconnection applications.
• Modules, inverters, batteries, racking, electrical equipment, and monitoring.
• Labour, access equipment, trenching, concrete, roofing work, or structural work.
• Electrical-panel, service, transformer, meter, or interconnection upgrades.
• Removal or relocation of existing equipment.
• Roof penetrations, flashing, weatherproofing, and restoration.
• Site cleanup and waste removal.
• Commissioning and customer orientation.
• Monitoring setup and long-term support.
• Items specifically excluded.

Unknown site conditions should be described before signing. If an electrical upgrade, structural reinforcement, roof repair, underground run, or utility requirement cannot be priced until inspection, say how it will be handled.

10. Describe the project process without promising impossible dates

Customers want to know what happens after signing. Provide a realistic sequence and explain which steps depend on third parties.

• Deposit and project kickoff.
• Site survey or validation.
• Final engineering and design approval.
• Permit and interconnection submissions.
• Equipment procurement.
• Installation scheduling.
• Installation.
• Inspection.
• Utility approval or permission to operate.
• Monitoring activation and closeout.

Separate contractor-controlled work from municipal, utility, financing, incentive, and equipment timelines. Give estimated ranges where appropriate and explain what can cause them to change.

11. State warranties precisely

Different warranties protect different things. Identify the provider, duration, and basic coverage of each one.

• Module product warranty.
• Module performance or production warranty.
• Inverter or microinverter warranty.
• Battery product, capacity-retention, or throughput warranty.
• Racking and balance-of-system warranties.
• Installer workmanship warranty.
• Roof-penetration or weatherproofing warranty when offered.
• Monitoring and service commitments.

Do not combine manufacturer and installer obligations into one vague “system warranty.” Explain how the customer requests service and who is responsible for diagnosing a future issue.

12. Include the commercial and legal terms

The final agreement should contain or incorporate the terms governing the work.

• Payment timing and late-payment terms.
• Customer cancellation rights where applicable.
• Change-order process.
• Site-access responsibilities.
• Customer obligations and required approvals.
• Title, ownership, and risk of loss.
• Insurance, licensing, and compliance statements where required.
• Limitations around utility, incentive, tax, financing, and production assumptions.
• Dispute and governing-law provisions.
• Signature blocks for the required parties.

Legal requirements vary by jurisdiction. Have the agreement reviewed by qualified local counsel rather than copying terms from another installer’s proposal.

13. Preserve acceptance evidence

An electronic signature should connect the customer to the exact proposal and terms accepted.

• The final document or version identifier.
• Signer name and role.
• Signature and timestamp.
• Consent to electronic records and signatures.
• Any required countersignature.
• An audit trail or acceptance record.
• A final copy delivered to the customer.

If a customer selects among several system options, the acceptance record should identify the chosen option rather than attaching a signature to an ambiguous group of alternatives.

14. Design for reading, not decoration

A proposal should look like the contractor who prepared it, but branding cannot rescue unclear information.

• Use a readable type size and strong contrast.
• Make price, system size, equipment, production, and next steps easy to find.
• Use charts only when they explain something the text cannot show as clearly.
• Label units, axes, time periods, and assumptions.
• Avoid repeating the same claim across several pages.
• Make web proposals usable on a phone.
• Provide a PDF or durable copy when appropriate.
• Keep important terms in the proposal, not only behind links the customer may never open.

15. Run a final consistency check

Common proposal warning signs

• The headline savings number cannot be traced to visible assumptions.
• The proposal shows a monthly payment but hides the cash price or financing cost.
• Production, utility savings, and bill offset are treated as the same number.
• The equipment list does not match the design image.
• Battery backup is described without load or operating assumptions.
• Important scope exclusions appear only after signing.
• Manufacturer warranties are presented as though the installer issued them.
• A specific installation or utility date is promised without accounting for outside approvals.
• The customer can sign without clearly selecting a system option.
• Operations cannot tell what changed between the designed, proposed, and accepted system.

Keep the proposal connected to the project

Powerlily’s design and proposal workspace carries the site model, equipment, production, storage, options, pricing, terms, delivery, and acceptance through the same project record. When the design changes, the proposal can be reviewed against the current technical and commercial system instead of becoming an independent copy.

The same record can continue into single-line diagrams, permit plan sets, invoicing, the client portal, and operations. For the wider workflow, read Run your solar EPC on Powerlily.

The best proposal is not the longest one. It is the proposal that lets the customer understand the decision and lets the contractor deliver the same project that was sold.