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1. Introduction

For industrial plants, construction sites, data centers, and hospitals, diesel generators remain one of the most dependable sources of independent power. While the purchase price of a generator is important, the real long-term value comes from understanding its operating cost per kilowatt-hour (kWh) — the actual cost required to produce one unit of electricity.

This article summarizes practical field experience, industry data, and performance differences among major brands to provide a clear and reliable reference for evaluating diesel generator operating costs.

2. What Determines the Operating Cost per kWh?

The cost of generating one kilowatt-hour mainly comes from four components:

1. Fuel Cost — the largest portion (70%–90%)

Fuel consumption is usually measured in g/kWh or L/kWh.
Typical consumption for industrial generator sets:

  • 200–230 g/kWh, equal to about 0.24–0.27 L/kWh
  • Efficiency improves as load increases (50% load has noticeably higher fuel use per kWh)

Example calculation:
Diesel price: 7 RMB/L (≈1 USD/L)
Fuel consumption: 0.26 L/kWh
Fuel cost per kWh:
0.26 × 7 = 1.82 RMB/kWh (≈0.26 USD/kWh)

2. Maintenance Cost

Includes:

  • Oil and filter replacements
  • Coolant changes
  • Routine inspection and labor

Average range:
0.05–0.12 RMB/kWh (≈0.01–0.02 USD/kWh)

High-end brands usually have longer service intervals and slightly lower maintenance costs.

3. Depreciation Cost

Depends on purchase price, lifetime, and annual operating hours.

Typical engine life:

  • Domestic brands: 15,000–25,000 hours
  • International brands: 25,000–40,000 hours

Usual depreciation cost:
0.05–0.25 RMB/kWh (≈0.01–0.04 USD/kWh)

4. Labor & Miscellaneous Costs

Varies by project:

  • Operators
  • Facility/room rental
  • Noise control
  • Cleaning and additives

Typical range:
0.02–0.05 RMB/kWh (≈0.003–0.01 USD/kWh)

3. Formula for Calculating Cost per kWh

Total Cost per kWh=Fuel+Maintenance+Depreciation+Other Costs\text{Total Cost per kWh} = \text{Fuel} + \text{Maintenance} + \text{Depreciation} + \text{Other Costs}Total Cost per kWh=Fuel+Maintenance+Depreciation+Other Costs

4. Operating Cost Comparison Among Major Diesel Generator Brands

Below is a comparison based on typical fuel consumption and maintenance figures for 500 kW–1500 kW generator sets.

1. Cummins

  • Fuel consumption: 0.235–0.255 L/kWh
  • Long service intervals
  • Service life: 25,000–35,000 hours

Operating cost: 1.70–2.10 RMB/kWh
Strengths: excellent efficiency, high reliability, strong global support
Best for: data centers, hospitals, critical loads

2. Volvo Penta

  • Fuel consumption: 0.22–0.24 L/kWh
  • Outstanding low-vibration and low-noise performance
  • 500-hour service interval

Operating cost: 1.65–2.00 RMB/kWh
Strengths: best-in-class fuel economy, very stable for long-term operation
Best for: factories, commercial buildings, continuous loads

3. Perkins

  • Fuel consumption: 0.24–0.26 L/kWh
  • Strong durability
  • Parts cost slightly higher

Operating cost: 1.80–2.20 RMB/kWh
Strengths: extremely reliable under harsh conditions
Best for: mining, oil fields, heavy-duty projects

4. Hyundai

  • Fuel consumption: 0.25–0.27 L/kWh
  • Easy maintenance, reasonably priced parts

Operating cost: 1.85–2.30 RMB/kWh
Strengths: reliable performance and competitive pricing
Best for: construction, industrial areas, commercial power supply

5. Chinese Brands (Shangchai / Weichai)

  • Fuel consumption: 0.26–0.30 L/kWh
  • Lower equipment cost
  • Inexpensive spare parts

Operating cost: 1.90–2.40 RMB/kWh
Strengths: excellent price-to-performance ratio
Best for: large-scale projects, cost-sensitive applications

5. Brand Comparison Summary

BrandFuel Consumption (L/kWh)Cost per kWh (RMB)Summary
Volvo Penta0.22–0.241.65–2.00Best fuel economy
Cummins0.235–0.2551.70–2.10Strong all-around performance
Perkins0.24–0.261.80–2.20Durable and stable
Hyundai0.25–0.271.85–2.30Cost-effective
Shangchai / Weichai0.26–0.301.90–2.40Budget-friendly

6. How to Reduce the Cost per kWh

1. Maintain a load of 70%–80%

Generators are least efficient at low load.

2. Use high-quality diesel

Poor-quality fuel increases consumption and speeds up wear.

3. Follow regular maintenance intervals

Clogged filters alone can raise fuel use by 5%–15%.

4. Choose generator models with better fuel efficiency

For long-hour applications, fuel savings far outweigh equipment price differences.

5. Consider parallel (synchronized) systems

Multiple units can automatically adjust to match load demand and improve overall efficiency.

7. Conclusion

Based on fuel consumption and overall operating cost:

  • Volvo Penta offers the lowest long-term cost per kWh.
  • Cummins provides the best balance of reliability and efficiency.
  • Domestic brands offer strong economic value for budget-focused projects.

Summary:
For fuel economy: choose Volvo.
For critical reliability: choose Cummins.
For cost-sensitive projects: domestic engines are the best value.