How to prepare for rooftop solar

If you are considering rooftop solar, prepare the information an installer needs before you compare equipment or financing. Start with a full year of electricity bills, a safe ground-level look at the roof and nearby shade, and a list of ownership or approval questions. Then ask each installer to explain the same roof, electrical, permitting, and utility assumptions in writing. Do not climb on the roof, open an electrical panel, or try to determine whether your structure or wiring is suitable yourself.

This guide is for a homeowner deciding whether it is time to request solar proposals. The practical answer is that a proposal is more useful after you have documented your electricity use and visible site conditions, while leaving roof, structural, and electrical conclusions to qualified professionals. Your next action is to make a short project folder and use it to request comparable written scopes.

1. Gather a full year of electricity use

Collect the most recent 12 months of electric bills if they are available. The bills show electricity use in kilowatt-hours (kWh), the unit your utility uses to measure energy. They can also reveal seasonal changes: a home with electric heating, air conditioning, a pool, or a new electric vehicle may use much more electricity in some months than others.

Note changes that could make past bills a poor picture of the future. Examples include a planned heat pump, an addition, a household member moving in or out, or a change in how you charge an electric vehicle. Give that context to every installer. The U.S. Department of Energy (DOE) advises homeowners to consider their electricity needs and how they may change before sizing a solar system.

Keep the bills as records, not as proof that a specific system will offset a specific amount of use. A production estimate also depends on the site and equipment.

2. Document roof information without inspecting it unsafely

From the ground, write down the roof areas that appear to receive the most sun and take dated photos if you can do so safely. Note the home’s approximate age, the roof’s approximate age if known, visible missing or damaged materials, and any known leaks or repairs. Do not use a ladder, walk on the roof, remove panels, or probe materials to answer these questions.

A roof that is near the end of its useful life, has active water entry, or needs substantial work may need attention before solar is installed. That does not mean a homeowner should diagnose the roof; it means the proposal should state whether a roofing evaluation or repair is needed and who is responsible for coordinating it. Ask the installer to identify any assumptions about roof condition, attachment locations, flashing, and access.

3. Notice shade and site conditions over time

Trees, chimneys, nearby buildings, and roof shapes can affect the sunlight that reaches panels. Take notes at different times of day if practical, especially when you see seasonal shade. A ground-level observation is useful context, but it is not a shade study or production model.

NREL’s PVWatts tool can help a homeowner understand how location, system settings, and other assumptions affect modeled production. Use it as a reasonableness check, not a design, savings guarantee, or substitute for a site assessment. Ask each installer what roof areas, shading assumptions, and weather data support the annual-production estimate in the proposal.

4. Confirm ownership and permission questions early

Check who can authorize work on the home. If you belong to a homeowners association, condominium association, historic district, or other community with exterior-work rules, ask what review or notification may apply. Requirements vary by location and community, so do not assume that a general online answer applies to your property.

Also ask the installer who handles local permits, utility interconnection, inspections, and any meter-related steps. A complete proposal should distinguish tasks the installer will manage from tasks the homeowner must complete. If the home is leased, jointly owned, or subject to a lender or insurance requirement, get the appropriate party’s answer before treating a proposal as ready to sign.

5. Ask about the electrical system; do not investigate it yourself

Solar equipment connects to the home’s electrical system and utility equipment through a design that must fit the site. Tell installers about known panel upgrades, frequent breaker trips, existing backup generators, batteries, or plans for large electric loads. Do not remove the panel cover or test wiring to answer their questions.

Ask whether the proposal assumes electrical-panel work, a service upgrade, new wiring, or coordination with another licensed professional. If the answer depends on a site visit or electrical assessment, request that the proposal label it as an open item rather than hiding it in a vague allowance.

6. Request proposals that answer the same questions

Use the same electricity records and project notes with each installer. Ask for a written proposal that identifies the proposed system capacity, equipment, annual-production estimate, roof assumptions, included and excluded work, cash price, financing terms if offered, warranties, permit and utility responsibilities, and the process for changes after a site visit.

Compare the scope before comparing a monthly payment or a price per panel. For a fuller comparison framework, read How much should solar panels cost?. Federal, state, utility, and local incentives can change and may have eligibility rules; check current program information with the relevant administrator and seek qualified tax advice when tax treatment matters. DOE points homeowners to DSIRE to research state and local policies and incentives, but a database listing is not a promise that you qualify.

Keep a simple project folder

Save bills, roof notes, photos, association correspondence, proposal versions, and questions in one place. Before authorizing work, make sure each open item has an owner and a written next step. That record helps you spot when two proposals describe different jobs and gives the professional a clearer starting point.

Sources

• U.S. Department of Energy, Homeowner’s Guide to Going Solar (accessed September 30, 2026).
• National Renewable Energy Laboratory, PVWatts Calculator (accessed September 30, 2026).
• DSIRE, Database of State Incentives for Renewables & Efficiency (accessed September 30, 2026).

Be ready for the conversation

3 questions to ask your solar installer

1. 1Which roof areas and shade assumptions will you use for this design, and what needs an on-site assessment before you finalize it?
2. 2What panel, wiring, permit, utility, and roofing work is included or excluded in this proposal?
3. 3If the site visit identifies a roof or electrical issue, how will you document the change and get my approval before work proceeds?