Path-Q Solar
Should I use the previous owner's electricity bills when sizing solar for a recently purchased home?
Answer
Use them as evidence, not as the sole forecast. Previous bills can reveal the property's seasonal baseline, but they may not represent your occupancy, appliances, heating, EV use, or planned renovations.
Key points
- Check whether the prior owner occupied the home for the full billing periods.
- Adjust for changes in occupancy, work schedules, heating, cooling, appliances, and electrification.
- A full year of bills is more useful than a short or unusually vacant period.
What it depends on
- Completeness and reliability of the bill history
- Differences between prior and future occupancy
- Changes to equipment or building condition
- Planned renovations and electrification
- Seasonal weather and operating patterns
Risks and trade-offs
- Using unusually low prior use can undersize the system.
- Using unusually high prior use can oversize it.
- Past bills may reflect different tariff, meter, or occupancy conditions.
Information you may need
- At least twelve months of prior bills if available
- Your expected occupancy and schedules
- Current equipment and planned changes
- Weather and vacancy information
- Current tariff and meter details
Your next step
What to do next
Give the bill history and a written list of your expected changes to the installer, and request a baseline-plus-adjustments load estimate.
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