Does a high annual wind yield mean I can reduce my backup generator size?

The short answer

Annual wind generation alone does not establish how much backup power a site requires. Generator sizing depends on the power deficit when wind is low, the loads that must remain supplied, motor starting and the agreed operating strategy. Two wind profiles can deliver the same kWh while creating different peak deficits. Use time-based scenarios for backup sizing and annual energy for fuel or electricity accounting.

Compare equal-energy profiles

Illustrative example: a constant 2 kW load operates for 20 hours, consuming 40 kWh. Wind profile A supplies 2 kW for the first 10 hours and zero for the next 10. Profile B supplies 1 kW for all 20 hours. Both provide 20 kWh.

Profile	Total wind energy	Largest simple power deficit
A	20 kWh	2 kW
B	20 kWh	1 kW

The totals match, but the peak deficits do not. These invented profiles illustrate the distinction; they are not a prediction of wind behavior.

Size for the agreed difficult case

Consider a calm period, an unavailable wind subsystem and a sudden load increase. The project must state which of those cases the backup source is expected to cover. Storage may alter the deficit only when its available power, usable energy, state of charge and controls are included.

Generator minimum loading, transfer behavior and starting capability also matter. A lower annual fuel estimate is not evidence that a smaller generator will accept the required load safely.

Make separate decisions for power and fuel

Use a load and operating-mode study to define backup capacity. Use an interval energy balance and the actual generator fuel map to estimate fuel consumption. Do not convert a percentage reduction in annual kWh into the same percentage reduction in generator kW.

For a wind enquiry, describe the critical load and existing generator separately from the desired wind-energy contribution. MARSTON equipment compatibility and operating interfaces need to be confirmed for the proposed system; the turbine rating does not establish a backup arrangement.