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Generac 40kW Standby Generator | 4.5L | Liquid-Cooled Gaseous Engine |Model XG04045

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The Generac Standby Generator Model XG04045 is your ultimate solution for reliable backup power. With an impressive 40kW output, this generator is designed to keep your home or business running smoothly during power outages. Equipped with a powerful 4.5L engine, this single-phase generator delivers consistent 120/240V power, ensuring all your essential appliances and sensitive electronics stay operational without interruption. Ideal for large homes and businesses, the Generac XG04045 provides the peace of mind you need.

SKU PCG-10040 Categories , ,


High-Capacity Backup Power for Critical Applications 

The Generac Protector® Series 40kW Standby Generator, model XG04045, offers powerful and reliable backup power to ensure your home or business remains operational during power outages. This high-capacity generator is designed with advanced technology and robust features to maintain essential systems and appliances without interruption. 

Key Features: 

  • Mobile Link™ Remote Monitoring: Stay connected and monitor your generator’s status from anywhere using a smartphone, tablet, or PC. Access real-time updates on operating status and maintenance alerts for complete peace of mind. 
  • True Power™ Technology: Provides superior power quality with less than 5% total harmonic distortion (THD), ensuring smooth operation for sensitive electronics and appliances. 
  • Generac’s Liquid-Cooled 4.5L Gaseous Engine: Built specifically for the demands of generator use, this engine delivers reliable power with minimal maintenance. Assembled in the USA with both domestic and foreign parts, it ensures high performance and durability. 
  • Quiet-Test™ Self-Test Mode: Runs at a lower RPM during self-tests for quieter and more fuel-efficient operation. Schedule tests weekly, bi-weekly, or monthly to ensure your generator is always ready. 
  • Durable Aluminum Enclosure: The RhinoCoat™ powder-coated finish ensures the aluminum enclosure is corrosion-resistant and suitable for all weather conditions, providing long-lasting durability. 
  • User-Friendly Power Zone® 410 Controller: Features a 128 x 64 graphical display with a heater, multi-lingual support, and comprehensive system status updates. Monitor voltage, current, power, oil pressure, coolant temperature, and more. 
  • 5-Year/2,000 Hour Limited Warranty: Enjoy long-term reliability and support with Generac’s comprehensive warranty. 

Innovative Design and Rigorous Testing: 

  • Solid-State, Frequency Compensated Voltage Regulation: Provides fast response to changing load conditions and maximizes motor starting capability with ±1% voltage regulation. 
  • Full Pressure Lubrication System: Ensures pressurized lubrication to vital bearings, enhancing performance, reducing maintenance, and extending engine life. 

Additional Benefits: 

  • Quick and Smooth Starting: The electronic ignition/spark advance ensures reliable and fast starts every time. 
  • Engine Protection: Features such as low oil pressure and high temperature shutdown safeguard the engine from damage. 
  • Voltage Regulation: Prevents harmful voltage spikes with ±1% regulation. 
  • Compliant and Safe: Integral sediment trap meets IFGC and NFPA 54 installation requirements. 
  • Easy Installation: Flexible fuel line connector listed ANSI Z21.75/CSA 6.27 for convenient gas supply connection. 
  • Quiet Operation: The enclosed critical grade muffler minimizes noise and enhances safety. 
  • Compact Design: The small footprint and attractive design allow for installation as close as 18 inches from a structure, fitting seamlessly into any environment. 


  • Model: XG04045 
  • Power Output: 40 kW 
  • Fuel Options: Natural Gas or Liquid Propane 
  • Voltage: 120/240V Single Phase, 208/120V 3-Phase, 240/120V 3-Phase, 480/277V 3-Phase 
  • Phase: Configurable for Single or 3-Phase 
  • Noise Level: 64 dB(A) at normal load, 58 dB(A) in Quiet-Test™ mode 
  • Engine: Generac Liquid-Cooled 4.5L Inline 4-Cylinder 
  • Battery Type: Group 27R, 725 CCA Minimum 
  • Fuel Usage: Natural Gas: 14.0 m³/h (494 CFH) at 100% load; Liquid Propane: 21.7 L/h (5.7 US gph) at 100% load 
  • Max Continuous Amps (Single Phase): 167A 
  • Weight: 1781 lbs (808.0 kg)  
  • Dimensions: 83.5 x 35 x 46 in (212.1 x 88.9 x 116.8 cm) 

Ensure your home or business remains powered and comfortable during any power outage with the Generac Protector Series 40kW Standby Generator, model XG04045. With advanced features, durable construction, and remote monitoring capabilities, this generator provides reliable backup power when you need it most. 

Choose the Generac XG04045 for unmatched power and peace of mind. 


Additional information

Weight 1781 lbs
Dimensions 83.5 × 34 × 45 in
Fuel Type

Liquid Propane or Natural Gas

Oil Type

Check chart in manual

Crankcase Capacity (L (US gal))

11 (2.9)

Battery Included


Battery Type

Group 27R, 725 CCA Minimum

Battery Size


Engine Type

4-cyl In-line

Operating Speed (RPM)


Quiet Test


Controller Type





28 kW –


40 kW

Max. Cont. Amps - 120/240 volts (LP)


Max. Cont. Amps (NG)


Sound Level at Operating Speed & No Load at 7 m (23 ft)

64 db

NG Consumption - 50% (m3/hr)


NG Consumption - 100% (m3/hr)


LP Consumption - 50% (l/hr)


LP Consumption - 100% (l/hr)


LP Vapor Pressue (kPa (in. WC))

1.74 – 3.48 (7–14)

NG Pressure (kPa (in. WC))

0.87 – 3.48 (3.5 – 14)


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