Why doesn't my formula meter show a calculated value or shows an error?

If your formula meter shows no value, a zero value, or a calculation error, work through this checklist:

1. Check that source meters have data

• Each source meter must have readings in the time period you are calculating
• Go to Analytics → Energy dashboard and verify each source meter has data in the selected range
• If any source meter has no readings, the calculation may return zero or "partial" status

2. Check the formula meter is active

• Open the formula meter and verify is_active is true
• Inactive formula meters are skipped during calculation

3. Check source meter units match

• All source meters in a formula should use the same unit (e.g., all kWh)
• Mixing kWh and MWh will produce incorrect results — convert units first

4. Check the time period and resolution

• When you click "Calculate", you must specify start time, end time, and resolution (hour, day, week, month)
• If the resolution is "month" but you selected only a 2-week range, results may be empty
• Try a broader range or finer resolution

5. Check for calculation status

• "success" — Calculation completed normally
• "partial" — Some source meters had data, others did not. The result uses available data but may be incomplete.
• "error" — Calculation failed entirely. Check the error_message field for details.

6. For custom formula type

• Use "Validate" before saving to check the expression syntax
• Meter references in the formula must match actual meter IDs
• Division by zero will cause an error

7. For rest usage type

• Verify the main meter is set and has data
• Verify at least one child meter is configured
• A negative result is not an error — it means sub-meters exceed the main meter

Where to check: Analytics → Formula Meters → click the formula meter → view its last calculation result and status.