By All Solar Power

A solar proposal is easier to evaluate when every installer starts with the same description of your home. Otherwise, one company may assume an electric vehicle is coming, another may ignore a shaded roof section, and a third may base its recommendation on a single expensive summer bill. You can end up comparing different projects instead of different offers.

A home energy brief is a short information packet, not a system design. Its purpose is to separate facts, plans, and unanswered questions before anyone recommends equipment. The following worksheet is an editorial planning aid for homeowners, not an electrical assessment or a promise of savings.

Start with electricity use, not just dollars

Gather a complete year of available electricity statements. Record each billing period and its consumption in kilowatt-hours (kWh). Keep the dollar total in a separate column. A high bill alone does not tell an installer whether the change came from greater consumption, a different rate, or another charge.

Flag gaps and unusual periods, such as an extended vacancy or temporary construction. Do not silently substitute a guess for a missing month. Ask the installer how missing information affects the proposal.

The Department of Energy recommends reviewing past bills to understand annual and seasonal electricity needs, and considering future changes such as electric-vehicle charging. It also points to an energy audit as a way to identify possible efficiency improvements before sizing a system. See DOE’s step-by-step consumer solar guide.

Separate confirmed changes from possibilities

Make two lists. The first contains planned changes with a reasonably firm timetable: for example, a purchased vehicle awaiting delivery. The second contains possibilities, such as a future workshop or a heating-system change that has not been selected.

Ask for the base proposal using current documented consumption, then request that any future-use scenario be shown separately. Label the assumptions explicitly. This keeps an appealing but uncertain plan from becoming an invisible reason for a larger project.

There is no need to invent exact consumption for equipment you have not chosen. An unresolved question is more useful than a precise-looking unsupported number.

Bring roof records and ground-level observations

Record the roof’s approximate age, material, known leaks, repair history, and any planned replacement. Include safe ground-level photos if useful. Note nearby trees, chimneys, or adjoining buildings without trying to quantify their effect yourself.

DOE identifies roof age, tree cover, size, shape, and slope as factors in suitability. It recommends a custom assessment rather than treating an online estimate as a final answer. A difficult roof is also a reason to investigate alternatives such as community solar, not to force a rooftop project. See the DOE Homeowner’s Guide to Solar.

Stay off the roof for this exercise. Leave structural suitability, roof attachments, wiring, and electrical-service evaluation to appropriately qualified professionals. Your brief should capture what you know, not certify conditions you cannot assess.

Ask what the production estimate assumes

Request the proposed system size, expected annual generation, and a monthly production breakdown. Ask which roof areas are included, how shade was assessed, and whether the calculation accounts for the conditions at your property. Keep the estimate’s date and version alongside the proposal.

PVWatts, the public solar-estimation tool, explains that its weather-based outputs describe typical or long-term conditions rather than guaranteeing a particular year’s result. Its guidance also warns that default losses can be optimistic where shade, snow, or soiling are greater than assumed. Use a preliminary calculation to frame questions, not as a production guarantee. Read the PVWatts guidance on interpreting results.

Keep your goal visible

Write one sentence explaining why you are considering solar. Perhaps you want to understand rooftop feasibility, compare ownership options, or investigate backup power. If backup is important, ask for that requirement to be addressed explicitly; do not assume a generation estimate answers it.

Then attach this one-page question list to each quote request:

• Which consumption records and future changes did you use?
• Which roof areas and site conditions did you assess?
• What additional inspection or documentation is still needed?
• Which assumptions differ from the brief, and why?
• What is included, excluded, optional, or dependent on later approval?
• Who will answer questions after the proposal is issued?

Keep an unanswered-items column instead of forcing every answer into “yes” or “no.” A useful first proposal makes uncertainty visible. Once competing proposals use the same starting facts, their differences become easier to discuss without relying on a headline panel count or a persuasive sales illustration.