Methodology → Generator vs Battery Cost

How Generator vs Battery Cost Is Compared

This page explains the fixed assumptions used on the generator vs battery cost comparison pages. The comparison is an operating-cost comparison only—battery recharge cost vs generator fuel cost per hour.

Fixed assumptions

The site uses these documented assumptions for the comparison:

  • batteryCapacityKwh = 13.5
  • batteryChargeEfficiency = 0.9
  • generatorFuelUseGallonsPerHour = 0.75
  • gasolinePricePerGallon = 3.75

Formulas

Battery recharge cost (with losses):

batteryRechargeCostWithLosses =
(13.5 / 0.9) * rateDollarsPerKwh

Generator cost per hour:

generatorCostPerHour =
0.75 * 3.75

Scope

The comparison excludes:

  • Purchase price of battery or generator
  • Maintenance costs
  • Installation costs
  • Outage performance (runtime, load capacity)
  • Battery lifespan and degradation

This is an operating-cost comparison only. Actual total cost of ownership depends on usage patterns, equipment lifespan, and local conditions.

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