Path-Q Solar
How can I tell whether my solar quote is based on realistic electricity use?
Answer
Compare the quote's modeled annual electricity use with your actual bills and expected future changes, and ask the installer to show every major assumption. A credible quote should distinguish measured historical consumption from estimates for future loads, weather, system losses, and degradation.
Key points
- Provide a complete set of bills or interval-use data when available rather than relying on one recent bill.
- Check whether the quote uses delivered electricity, solar production, or another metric, and whether it accounts for seasonal variation.
- Identify planned EV charging, electric heating, cooling, water heating, additions, occupancy changes, and efficiency upgrades.
- Ask for monthly production and consumption estimates, not only an annual offset percentage.
What it depends on
- Completeness and representativeness of utility-use records
- Household occupancy and operating patterns
- Planned electrification or efficiency changes
- System orientation, shading, and modeled losses
Risks and trade-offs
- Sizing from an unusually low-use year can undersize the system; sizing from temporary high use can oversize it.
- A high modeled offset does not guarantee equivalent bill savings because billing structures and export treatment vary.
- Future use estimates can be uncertain, so the quote should show sensitivity rather than one precise forecast.
Information you may need
- At least several months of bills, preferably a full year
- Any interval data or utility consumption history available
- Planned changes to vehicles, heating, cooling, appliances, occupancy, or the building
- The quote's load assumptions and monthly model
Your next step
What to do next
Ask the installer to reconcile the modeled annual and monthly use with your bills and provide a revised model for each material future-load scenario.
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