Ground Power Units (GPUs) keep aircraft powered during turnaround, maintenance and pre-flight checks. Choosing between diesel, battery-electric, and hybrid models is no longer only a technical decision—it’s a strategic one that affects operating cost, emissions, working conditions and infrastructure planning. This guide summarizes what buyers should know in 2025, from power standards and duty cycles to total cost of ownership (TCO) and charging strategy.

1) What a GPU actually supplies

Most commercial operations need one or both of the following outputs:

• 400 Hz AC (typically 115/200 V, 3-phase) for main onboard systems. Power bands: 40–180 kVA for narrow- and wide-body applications.
• 28.5 V DC for avionics and starting, often 600–1200 A peak. Business aviation and rotorcraft rely heavily on this.

Modern GPUs may combine both outputs or specialize in one. Always match peak and continuous loads, connector types, cable lengths, and ambient conditions (hot/cold/high altitude) to your fleet mix.

2) The options: diesel, battery, hybrid

Diesel GPUs

• Strengths: Highest autonomy, works everywhere, easy to refuel, robust in harsh climates. No charging infrastructure required.
• Trade-offs: Exhaust and noise, idling penalties, fuel price volatility, more preventive maintenance (engine, fluids, filters, aftertreatment).
• Best for: Remote stands, small airports without power upgrades, high seasonal variability, “bring-your-own-power” operations.

Battery-electric GPUs

• Strengths: Zero local emissions, very low noise, minimal daily maintenance. Excellent for night operations, noise-sensitive terminals and indoor hangars.
• Trade-offs: Requires charging strategy and grid capacity; range depends on ambient temperature and duty cycle; higher upfront CAPEX (offset by OPEX savings).
• Best for: High-utilization gates with power access, airports with decarbonization targets, long-term OPEX reduction plans.

Hybrid GPUs (engine + battery)

• Strengths: Engine runs at optimal efficiency while battery covers peaks and short stops. Lower fuel consumption and noise than pure diesel, less dependence on chargers than pure battery.
• Trade-offs: More complex system; still has engine emissions; needs periodic charging or regenerative strategies to keep the battery healthy.
• Best for: Phased transitions to electric, mixed operations with irregular access to power.

3) Quick comparison

4) Duty cycle and energy sizing

Duty cycle defines how long the GPU supplies power per turnaround and how many turns you run per shift. For battery models, convert your kVA × duration or DC current × duration into energy (kWh) and add a buffer for temperature and degradation. For diesel and hybrid, keep an eye on idling time—hybrid systems can drastically reduce it by letting the battery handle light loads.

5) TCO model (5–7 years)

• CAPEX: unit price, optional outputs, cable management, charger(s) and infrastructure, telematics.
• Energy: diesel (L/h × hours × price) vs. electricity (kWh × price). Consider tariffs and potential PV/green PPAs.
• Maintenance: diesel PM vs. electric PM; hybrid is in-between.
• Availability: downtime cost, spares, technician training, warranty terms.
• Residual value: depends on battery SOH and engine hours.

Rule of thumb: Above ~2,000 operating hours per year per unit, battery-electric GPUs often beat diesel on TCO—provided your electricity price and charger utilization are reasonable.

6) Standards & compliance

• Electrical quality: steady 400 Hz frequency, voltage regulation, THD limits; ripple for DC.
• Aircraft connectors and safety interlocks; cable heating; overload protection.
• Certifications & QA: ISO 9001/14001/45001, CE/UL where relevant, EMC compliance, OEM approvals.

7) Charging strategy for battery/hybrid GPUs

• Power levels: overnight L2 vs. fast charging during slack times. Avoid frequent 100% fast cycles if not necessary.
• Placement: close to gates to reduce dead mileage; weather-protected; intuitive cable management.
• Smart charging: schedule against peak tariffs; use load management to protect the substation.
• Battery care: keep within friendly SoC bands for longevity; thermal management matters in cold/hot climates.

8) Decision flow (simple)

9) Common pitfalls

• Undersized battery packs for winter operations → plan for temperature derating.
• Ignoring cable/connector life → check bend radius, strain reliefs, reels, and spare sets.
• No telemetry → visibility of usage, faults, and charging improves uptime and TCO.