Write down the job solar should do
Residential solar can reduce purchased electricity, support daytime activities and contribute to a broader resilience plan. Those are related goals, but they are not interchangeable. A household trying to lower annual bills may choose differently from one trying to run essential loads during outages. Write your main objective in one sentence before comparing equipment.
Collect a full year of electricity bills if available, along with interval data from your utility or meter. Annual consumption gives scale; the timing of consumption shows opportunity. A home occupied during the day may use generation directly. A home with mostly evening demand may export more electricity or consider shifting suitable tasks. Neither pattern automatically makes a battery worthwhile.
Check the roof before counting panels
Roof age, covering condition, structural capacity, orientation and shading belong near the beginning of the conversation. Replacing an aging roof after installing panels can add removal and reinstatement work. Trees, chimneys and neighboring buildings may cast different shadows across seasons, so one sunny afternoon is not a complete assessment.
Review what you can see safely from the ground. Do not climb onto a roof to estimate its suitability. Ask an appropriately qualified installer or building professional to address access, waterproofing, wind exposure, fire access and structural questions. Ground-mounted systems introduce different land-use, foundation, cable-route and permitting considerations.
Separate energy from power
A kilowatt, written kW, describes power at a moment. A kilowatt-hour, written kWh, describes energy over time. Panel capacity is not a promise of constant output: weather, temperature, shade, orientation and system losses all affect production. Ask for monthly estimates rather than relying only on an annual headline.
The US National Renewable Energy Laboratory’s PVWatts Calculator can help explore production assumptions for a location. It is an estimate, not a site survey, performance guarantee or financial quotation. Check that the location, array orientation, shading assumptions and system losses reflect the proposal you are considering.
Understand the inverter and the grid connection
The inverter converts panel output into electricity compatible with household equipment. Its configuration also helps determine monitoring, expansion options and compatibility with storage. A standard grid-connected solar system generally disconnects during a grid outage to avoid unsafe energization. Panels alone therefore do not establish an emergency power supply.
If backup is a goal, ask which equipment establishes an isolated supply, which circuits it supports and whether the battery can recharge from solar while the grid is unavailable. These capabilities must be confirmed for the complete proposed system. The word “hybrid” on a product description is not enough to establish every operating mode.
Compare proposals on matching assumptions
Request the same information from each provider: installed capacity, usable roof area, predicted monthly output, export limitations, monitoring access, warranty responsibilities and the work excluded from the price. Separate product warranties from workmanship cover and from estimates of future production. Ask who handles a fault if the original installer is no longer available.
Financial results depend on your tariff, export payment, timing of use, financing and local incentives. Check current terms with the utility and relevant public program rather than assuming another household’s savings will apply. Include likely maintenance, any roof work and possible electrical upgrades in the comparison.
| Planning item | Question to resolve | Who to involve |
|---|---|---|
| Roof and structure | Is repair or reinforcement needed first? | Qualified building professional |
| Electrical service | Does the proposed connection require an upgrade? | Licensed electrical contractor |
| Export and approval | What limits and permissions apply? | Utility and local authority |
| Outage operation | Which loads work when the grid is absent? | System designer and installer |
Leave room for an ordinary household future
Consider plausible changes without designing around every possibility. An electric vehicle, heat pump or home-working routine may alter demand, but uncertain future loads should remain clearly labeled assumptions. Ask what expansion would require, whether monitoring data can be exported, and whether equipment depends on an ongoing cloud service.
A sensible next step is a short planning brief: your current demand, roof concerns, daytime routines and outage expectations. Use it to request comparable assessments. Reducing avoidable demand first often makes the resulting design clearer, even when it does not change the number of panels.
Review household demandConsider backup needs