How should I compare repairing a wind system with replacing it?

The short answer

Compare future alternatives from the decision date, including their complete technical scope and remaining service. Past spending is not recovered by choosing a repair, but present equipment may still provide useful service after a properly assessed repair. A replacement needs its own installation, compatibility and energy case. Do not compare a component-only repair quote with an incomplete whole-system replacement price.

Define feasible options before valuing them

Identify the actual fault, equipment model and revision, service condition and available documentation. Establish whether the proposed repair is technically appropriate and whether the remaining system can continue operating under its approved requirements. An economic advantage cannot make an unverified repair compatible or acceptable.

For replacement, identify retained towers, foundations, cables and controls separately from new equipment. Reuse must be supported by an engineering assessment; a matching power rating does not establish that the interfaces or loads are suitable.

Use a common remaining-period comparison

Hypothetical undiscounted screen over five years: repair costs 4,000 now and is assumed to provide 1,500 of annual net benefit, giving 7,500 − 4,000 = 3,500. Replacement costs 12,000 now and is assumed to provide 2,500 annually, giving 12,500 − 12,000 = 500.

The repair leads under that deliberately limited case. The conclusion could change with different remaining life, repair risk, later costs or a justified remaining value for the replacement. The figures are not MARSTON prices, service-life promises or forecast savings.

Keep scope and uncertainty visible

Use discounting and year-specific costs for a complete model. Include foreseeable service, disposal, downtime and any required local work. State whether differences in availability and production have evidence or are only sensitivity assumptions.

The useful output is a decision record: feasible repair scope, feasible replacement scope, common comparison period, supported performance cases and unresolved risks. This is more informative than either a sunk-cost argument or a claim that new equipment must automatically be the better economic choice.