Compare the roof and the electricity as one project.

Building-integrated photovoltaics, often called BIPV, combine an electrical function with a building component. In a solar roof, generating units participate in the roof covering. For example, GAF’s Timberline Solar system combines energy shingles with conventional shingles. That does not mean every square foot of the roof generates electricity.

With conventional rooftop solar, modules and their mounting system sit above the roof covering. The solar design and the roofing design still need to agree on attachment, penetrations, water management and service access. Ask to see both layouts on the same drawing, including vents, valleys and equipment.

The DOE homeowner guide identifies roof age, shade, size, shape and slope as suitability factors. Start with the installation history and current condition. Record existing leaks, prior repairs and expected roof work. A satellite image can help estimate sun exposure, but it cannot describe the condition of concealed decking.

Request a written account of what the installer inspected, what remains concealed, and how unexpected deck repair is priced. If replacement is approaching, price coordinated roofing and solar work. If the roof is serviceable, ask what would justify removing it now and compare that explanation with keeping it and installing a compatible panel system.

Capacity in kilowatts describes system size; energy in kilowatt-hours describes production over time. Ask both bidders for estimated annual kWh and monthly production using the proposed layout. Have them identify shading, orientation, equipment and losses included in the estimate. A larger rated system is not automatically the one that best meets the household’s needs.

For a simple invented example, suppose annual household use is 12,000 kWh and estimated annual solar production is 9,000 kWh. Production is 75% of annual use. That arithmetic does not mean a 75% bill reduction: production and consumption happen at different times, and purchased and exported electricity can have different values.

Give bidders the same electricity-use history and planned changes, such as an electric vehicle. DOE’s project sequence recommends reviewing bills and future needs. Ask for tariff assumptions and separate cash price, financing charges and any claimed incentives so you can examine each part.

A complete proposal should distinguish roof leaks, electrical equipment defects and energy-production commitments. Write down the first service contact for each, the covered labor, and the terms for removing and restoring roof or solar components. Ask how a future reroof, home sale or discontinued product affects service.

Include monitoring setup and owner access in handover. Ask what happens during a utility outage and what equipment, if any, is included for backup operation. Do not infer backup capability merely because the house has solar panels or solar shingles.

Before signing, request the roof plan, equipment schedule, annual-production assumptions, permit responsibilities and closeout documents. Use the roofing quote comparison to align the building work; then compare the energy and service proposals on that same foundation.