Path-Q Solar
Can a solar system be sized for a new home before it has an electricity bill?
Answer
Yes. Without a bill, sizing must use an engineering estimate based on the home's size, envelope, climate, appliances, heating and cooling systems, occupancy, and planned electrification. Treat the result as provisional and update it after measured use is available.
Key points
- Model major loads separately rather than relying only on floor area.
- Include electric heating, water heating, vehicles, pools, workshops, and other future loads.
- Use equipment specifications and expected operating schedules where available.
- Allow for uncertainty and confirm that the design can accommodate actual consumption.
What it depends on
- Building size, insulation, air tightness, and climate
- Heating, cooling, and water-heating systems
- Appliances, occupancy, and operating schedules
- Planned electric loads
- Roof, service, and inverter capacity
Risks and trade-offs
- A floor-area estimate alone can be inaccurate for highly efficient or highly electrified homes.
- Construction changes and occupant behavior can materially change actual use.
- Oversizing or undersizing is possible when equipment selections are not final.
Information you may need
- Building plans and energy-efficiency specifications
- Final or proposed equipment schedules
- Expected occupancy and appliance use
- Future EV, heating, and other electric loads
- Roof orientation, shading, and electrical-service information
Your next step
What to do next
Request a modeled load calculation with explicit assumptions and a follow-up plan to compare it with the first several months of actual bills or interval data.
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