Small wind / Buyer questions
Energy and economics
Can I combine wind records collected before and after moving a measurement mast?
The short answer
Records from before and after a mast relocation should remain identifiable as separate measurement configurations. They can be combined only through a defensible interpretation of the location change. Simply appending the rows assumes the new position represents the old one, even if terrain, obstacles or height have changed.
Create a relocation record
Record the old and new coordinates, sensor heights, installation dates and relevant geometry. Preserve photographs and the reason for moving. Note whether instruments, booms or logger settings also changed, because several simultaneous changes make attribution harder.
Keep separate configuration identifiers in the dataset. A continuous date column does not establish a continuous resource exposure. Even a move within one property can matter near an obstacle or terrain boundary.
Evaluate comparability with actual evidence
If concurrent observations or a stable reference are available, ask how they support a transfer between positions. Examine directional and seasonal differences rather than assuming one constant adjustment works everywhere. A short overlap may leave important conditions untested.
Where no suitable link exists, retain the periods separately and report the uncertainty. Do not invent a normalization factor solely to remove a step in the annual trace. The step may contain a genuine location effect that the investment assessment needs to understand.
State where the final estimate applies
Identify whether the energy assessment represents the old location, the new location or a proposed turbine position different from both. Show the sequence of transfers and distinguish measured observations from adjusted values.
The decision may be to extend measurements at the final position rather than merge incompatible periods. A clear relocation history lets the buyer evaluate that trade-off. It also prevents a long-looking combined record from implying that one fixed installation location has been observed continuously for the entire campaign.
Sources
- U.S. DOE Small Wind Guidebook: resource and siting background
- NREL wind-resource assessment report: measurement analysis and long-term correlation
Examples are illustrative. Confirm product-specific performance, compatibility and supply scope in the applicable documents.