Path-Q Solar
When should I wait for more electricity-use data before sizing solar?
Answer
Wait when current usage is unusually low, high, or temporary, or when major changes such as electrification, an EV, occupancy changes, renovations, or business expansion are expected. If current bills do not represent future use, use multiple years of records where possible and model credible future scenarios rather than sizing only from a short period.
Key points
- At least a reasonably representative usage history is more useful than a single bill.
- Separate seasonal variation from one-time events or abnormal occupancy.
- Include planned heat pumps, electric water heating, EV charging, batteries, and efficiency improvements.
- Do not automatically size to maximum future use if the added load is uncertain or avoidable.
What it depends on
- Length and representativeness of utility history
- Occupancy and appliance changes
- Planned electrification and efficiency projects
- Utility billing and system-sizing constraints
Risks and trade-offs
- Waiting can delay savings or cause design and pricing assumptions to change.
- Sizing from an atypical low-use period can undersize the system.
- Sizing for speculative future loads can increase cost without producing useful savings.
Information you may need
- Recent utility bills and interval data if available
- Occupancy and seasonal-use history
- Planned EV, heating, cooling, and efficiency changes
- Installer's scenarios for current and future consumption
Your next step
What to do next
Gather representative usage data and list committed versus uncertain future loads, then ask for separate system designs for current and plausible future consumption.
Path-Q
Find the right next step
Answer a few questions and we’ll narrow your options.
Loading…
SQ00637