Solar Turbines Centaur 40

3,515 kWe ISO generator set, the highest-volume Solar package in the used equipment fleet

Solar Turbines Centaur 40 is one of 21 gas turbines tracked in the SecondWatt catalogue, each with specifications, lead times and indicative secondary-market pricing.

Solar Turbines Centaur 40 gas turbine: 3,515 kWe rating, SoLoNOx emissions data, overhaul guidance, and verified used pricing from about 79 dollars per kW.

The Centaur 40 is Solar Turbines' entry-level power-generation package: a single-shaft industrial gas turbine, main reduction gearbox, and synchronous generator built onto one skid-mounted enclosure, rated 3,515 kWe ISO base load at a heat rate of 12,240 Btu/kWe-hr and 27.9% thermal efficiency. It shares its common engine skid with the Centaur 50 and Taurus 60, and both 1500 rpm (50 Hz) and 1800 rpm (60 Hz) reduction-drive outputs are offered. Both conventional and SoLoNOx (dry low-emissions) combustion are sold as factory options on current production. The used market for this class runs deeper than for any larger Solar frame, and it runs under more names than the current catalog suggests. Nameplates including 4701, T4701, and Type H all describe engines converging on the same 3.0-3.5 MW class from earlier points in Solar's naming history, with no OEM crosswalk table connecting them to "Centaur 40." A buyer searching only the current model name can miss real inventory listed under a legacy tag. SoLoNOx became a factory option in 1992, carrying a 9 ppm NOx warranty; a real California BACT permit for this model, with SCR added, runs 5 ppmvd NOx, while the federal NSPS floor sits at a much looser 42 ppm. No overhaul interval in fired hours was sourced for this model; the best proxy is a 32,000-fired-hour rotor life figure from a third-party overhauler.

Why it matters

This is the most numerous Solar generator set in the secondary market, which makes it the fastest to deliver, a real advantage for a data center buyer who cannot wait for a Titan or Mars slot. That depth comes with a real cost: a wide spread of legacy nameplates and pre-1992 non-SoLoNOx units means emissions compliance and parts sourcing both demand more diligence here than on a newer, single-designation model.

Who buys it

Oil and gas operators, industrial cogeneration sites, and increasingly data center developers who need power sooner than a Titan- or Mars-class order can deliver buy the Centaur 40 for its combination of low unit cost and fleet depth. A buyer priced out of larger Solar frames, or unwilling to wait on new-build lead times, can often source two or three Centaur 40 units in place of one larger machine.

Key specifications

Technical summary

ISO base-load electrical output: 3,515 kWe Heat rate: 12,240 Btu/kWe-hr (12,910 kJ/kWe-hr) Thermal efficiency: 27.9% Pressure ratio: 10:1 Exhaust flow / temperature: 150,715 lb/hr (68,365 kg/hr) at 830F (445C) Combustion system: SoLoNOx (DLE) or conventional, factory option SoLoNOx emissions warranty: 9 ppm NOx / 15 ppm CO / 15 ppm UHC Main reduction drive output speed: 1,500 / 1,800 rpm (50 / 60 Hz) Package weight / height: 67,150 lb (30,460 kg) / 10'5" (3.2 m) Legacy nameplates in the used fleet: 4701, T4701, Type H

Compatibility and dependencies

The generator-set (single-shaft) Centaur 40 is a distinct product from the Centaur 40 mechanical-drive package, which uses a two-shaft, free-power-turbine arrangement to drive a gas compressor rather than a generator, sharing only the core engine. The generator-set version shares its common engine skid and reduction-gearbox family with the Centaur 50 and Taurus 60, which broadens parts availability for the shared components but not for the turbine hot section itself.

Pricing and availability

Published price range: $270,000 - $2,800,000. Trend: flat No time-series data exists in the sources checked, so a directional trend cannot be established, and price_trend is set to flat as a neutral default pending more observations over time. Lead time, used or refurbished: Not established from sourced listings; several used units were offered zero-hours-since-rebuild or immediately available..

Lifecycle and maintenance

The best available proxy is EthosEnergy's third-party rebuild spec, not an OEM interval: 32,000 fired hours of expected rotor life after a factory-equivalent overhaul. Against used-unit prices as low as $270,000, a six-figure overhaul consumes a far larger share of asset value on a machine this size than the same work on a 15-30 MW frame.

Common failure points

• Combustor liner and fuel nozzles — elevated or uneven exhaust temperature spread across cans, visible coking on borescope
• Hot gas path blades and nozzles (3-stage reaction turbine) — coating spallation, tip rub marks, or cracking visible on borescope images
• Main reduction gearbox — rising bearing temperature or metal particulates in oil analysis
• Generator windings — falling insulation-resistance trend or hot spots on thermal scan
• Control console and Turbotronic electronics — obsolete card sets or no vendor firmware support on pre-2005 consoles
• Fuel system and dual-fuel changeover hardware — sticking valves or failed changeover on units idle for years
• Enclosure and inlet/exhaust ductwork — corrosion or acoustic panel degradation on outdoor-stored units

Inspection checklist

Total fired hours since new — compare against the 32,000-hour rotor life benchmark cited by third-party overhaul shops Fired hours since the last hot section inspection — request the logged number, not a verbal estimate Total starts logged — each start-stop cycle drives more thermal fatigue than an hour of steady running Borescope images dated within the last 12 months — request the actual photo set, not a summary paragraph Combustion system type in writing — SoLoNOx trims NOx to roughly 9 ppm versus 40-plus ppm uncontrolled SoLoNOx conversion date if retrofitted — factory SoLoNOx was not standard across the line until 1992 Turbine blade and nozzle condition across the 3-stage reaction turbine — check for coating loss or cracking Fuel nozzle count and condition — 10 injectors on the annular combustor; check for coking or erosion Main reduction gearbox oil analysis — shared 1500/1800 rpm gearbox design across 3 Solar model lines Generator insulation resistance test result and date — a megohm reading, not a pass/fail claim alone Generator bearing vibration trend over the last 12 months — a trend line, not a single data point Control system generation — pre-2005 consoles predate Solar's InSight remote-diagnostics platform Enclosure and skid corrosion — package weighs 67,150 lb; outdoor or coastal storage accelerates this Number of prior installation sites — a relocated package carries more requalification risk than a single-site unit Nameplate cross-check against legacy designations — Centaur 40, 4701, 4701S, and Type H tags describe overlapping hardware with different parts and SoLoNOx eligibility

Procurement channels

Machinio-aggregated prices did not always reconcile with a seller's own live inventory page checked the same day, so a buyer should confirm any aggregator price directly with the seller before relying on it.