Overview#
The Generac SG045 is a 45 kW standby natural gas and LP vapor generator set built on Generac's 4.5-liter naturally aspirated inline-4 spark-ignited engine. Rated at 56 kVA standby and 51 kVA prime at 60 Hz, the SG045 uses the same engine platform as the SG035 but is tuned to a higher output — the engine runs at higher BMEP (113 psi standby vs 88 psi on the SG035), which is worth noting at service intervals.
Standard equipment includes the Power Zone Pro controller with NFPA 110 Level 1 compliance, a factory-installed radiator rated for 50°C (122°F) ambient, and dual fuel shutoffs. The SG045 carries UL 2200, UL 6200, and CSA C22.2 listings and EPA stationary emergency certification. Level 1 and Level 2 sound-attenuated enclosures are available in steel or aluminum, rated for up to 200 mph wind loads by factory order.
The Power Zone Pro controller supports Modbus RTU, Modbus TCP/IP, and Ethernet 10/100, with SNMP and remote software update capability — making the SG045 straightforward to integrate into BMS or remote monitoring platforms.
Technical Specifications#
Power Ratings (60 Hz, 1800 rpm)
| Rating | kW | kVA |
|---|---|---|
| Standby | 45 | 56 |
| Prime | 41 | 51 |
Engine — Generac 4.5L Inline-4 SI
| Parameter | Value |
|---|---|
| Displacement | 4.5 L (275 in³) |
| Configuration | Cast iron inline 4-cylinder |
| Aspiration | Naturally aspirated |
| Compression ratio | 9.94:1 |
| Rated speed | 1,800 rpm |
| Emissions | EPA Certified Stationary Emergency |
| Oil capacity | 21 qt (20 L) |
| Fuel type | Natural gas, propane vapor |
| Fuel inlet pressure (NG) | 5–14 in WC (1.2–3.5 kPa) |
| Fuel inlet pressure (LP) | 7–14 in WC (1.7–3.5 kPa) |
Fuel Consumption — Natural Gas (standby rating)
| Load | Consumption |
|---|---|
| 25% | 195 scfh |
| 50% | 322 scfh |
| 75% | 427 scfh |
| 100% | 554 scfh |
Physical (Open Set)
| Dimension | Value |
|---|---|
| Length | 78.1 in (1,984 mm) |
| Width | 37.3 in (947 mm) |
| Height | 44.4 in (1,128 mm) |
| Dry weight | 1,675–1,748 lbs (760–793 kg) |
Level 1 acoustic enclosure: 94.8 × 38.0 × 57.5 in, steel 2,258–2,329 lbs.
Control System — Power Zone Pro
Power Zone Pro provides NFPA 110 Level 1 compliance, digital voltage regulation (±0.25% steady state), electronic governor control, and a 4.3-inch color touch screen. Communications: Modbus RTU, Modbus TCP/IP, Ethernet 10/100, SNMP. Built-in programmable logic, expandable analog and digital I/O, and remote software update. Alarm and event logging with real-time stamping standard.
Our Service Experience#
The SG045 shares its engine with the SG035 but runs it at meaningfully higher load — 113 psi BMEP at standby vs 88 psi on the SG035. In practice this means we pay closer attention to spark plug condition at the 1,000-hour mark and fuel quality on SG045 units. Natural gas quality varies by region, and a higher-BTU or wetter gas supply will push combustion temperatures up on an already harder-working naturally aspirated engine. We inspect plugs at every 500-hour oil change and replace at 1,000 hours regardless. The Power Zone Pro control is well-suited to BMS integration — the built-in Ethernet and Modbus TCP/IP make commissioning with building management systems straightforward without third-party converters.
Frequently Asked Questions#
What is the difference between the SG035 and SG045? Both use the same Generac 4.5L inline-4 engine and Power Zone Pro controller. The SG045 is tuned for higher output (45 kW vs 35 kW) and consumes more fuel at full load (554 vs 446 scfh NG). The physical footprint and enclosure sizes are identical. For installations where future load growth is likely, the SG045 provides meaningful headroom over the SG035.
What voltages does the SG045 support? 120/240V single-phase at 1.0 pf, and 120/208V, 120/240V, and 277/480V three-phase at 0.8 pf. The 346/600V configuration available on the SG035 is not listed in the SG045 spec sheet.
Does the SG045 meet NFPA 110 Level 1 requirements? Yes. The Power Zone Pro controller is NFPA 110 Level 1 compliant as standard. The unit accepts full rated load transfer per NFPA 110 requirements for Level 1 emergency power supply systems.
What fuel pressure does the SG045 require? Natural gas supply pressure of 5–14 in WC at the generator fuel inlet. LP vapor requires 7–14 in WC. Verify that the gas meter and utility regulator can deliver adequate pressure and flow at 554 scfh full-load consumption.
What enclosure options are available? Open set, weather-protected, Level 1 acoustic, and Level 2 acoustic in steel or aluminum. Wind load rating up to 200 mph is available by factory special order. Enclosure heaters, motorized dampers, and AC/DC lighting kits are available options.
