1. Differences in Core Working Principles

1.1 Traditional Braking Resistor Solution (Energy Dissipation Type)

As a standard industry basic solution, the traditional elevator braking resistor is a passive heat-dissipating energy-consuming device. During elevator heavy-load downward operation, light-load upward operation and deceleration braking, a large amount of regenerative power is generated. This solution has no energy recovery function and converts all regenerative power into heat energy through the braking resistor, which is directly dissipated into the machine room air.

It only fulfills the basic functions of stabilizing inverter voltage and protecting electrical equipment, completely wasting the regenerative energy generated by elevator operation. Meanwhile, it continuously increases the ambient temperature of the machine room, serving as one of the core causes of high elevator energy consumption and overheated machine rooms.

1.2 Supercapacitor Energy-Saving System (Energy Storage and Reuse Type)

The elevator supercapacitor energy-saving system is an active energy storage and reuse solution, equipped with bidirectional DC/DC conversion modules and a supercapacitor energy storage array. The regenerative power generated by elevator braking and inertial coasting is no longer wasted as heat, but is real-time stored in the supercapacitor module. When the elevator requires peak power for starting, accelerating and heavy-load upward operation, the energy storage system preferentially releases stored power for equipment use, forming a closed-loop energy-saving system of "power generation – energy storage – reuse".

The system realizes full DC-side energy interaction without grid-connected filtering, featuring high energy conversion efficiency. It also suppresses instantaneous grid impact caused by elevator start-stop, delivering dual values of energy saving and grid voltage stabilization.

2. Comparison of Measured Power-Saving Effects

2.1 Braking Resistor Solution

Power Saving Rate: 0%

It has no energy recovery and power-saving capability, with 100% loss of all braking regenerative power. Instead of saving energy, the continuous heat generation of resistors raises the machine room temperature, indirectly increasing additional energy consumption of air conditioning and ventilation equipment. It is a pure energy-consuming basic solution with zero energy saving and secondary energy loss.

2.2 Supercapacitor Energy-Saving System

Comprehensive Measured Power Saving Rate: 28%–45%, stable and traceable energy-saving effect suitable for high-frequency start-stop elevator scenarios

• Low-frequency elevators in residential buildings: average power saving rate of 28%–32%

• High-frequency start-stop elevators in office buildings and shopping malls: average power saving rate of 35%–40%

• High-frequency no-load and light-load working conditions: the optimal measured power saving rate reaches approximately 45% (affected by elevator load ratio, start-stop frequency and floor height)

Field case verification: After renovating high-frequency elevators in commercial complexes, the daily power consumption of single elevators is significantly reduced with long-term stable energy-saving performance. For elevator cluster renovation projects in large office buildings, the annual comprehensive power saving exceeds 150,000 kWh with considerable energy-saving benefits. Meanwhile, the system reduces transformer peak load by about 15%, effectively cutting grid impact loss and peak-period electricity costs.

3. Detailed Full-Life Cycle Cost Comparison (One-Time Investment + Annual Operation and Maintenance)

3.1 Initial Investment Cost

Braking Resistor Solution: Extremely low initial cost with the lowest procurement and installation cost for single equipment. No complex supporting equipment is required, making it a low-cost temporary adaptation solution.

Supercapacitor Energy-Saving System: The one-time initial investment is higher than that of braking resistors. It requires supporting supercapacitor modules, bidirectional DC/DC converters and intelligent control modules. Featuring high equipment integration, its overall investment is higher than traditional resistor solutions.

3.2 Annual Operation and Replacement Cost (Core Gap)

Braking Resistor Solution (High Operation and Maintenance Cost)

Long-term high-temperature heating and repeated thermal expansion and contraction cause shell aging, resistance drift and wire breakage faults, making resistors common high-frequency wearing parts for elevators. Under conventional commercial high-frequency working conditions,inspection or replacement is required every 1–2 years. Long-term operation brings potential safety hazards such as insulation aging and overheating fire risks. The average annual cost of single elevator for accessory replacement, line inspection and fault handling is about RMB 3,000–5,000, and the operation and maintenance cost of multi-elevator clusters accumulates year by year. In addition, continuous heat accumulation in the machine room increases energy consumption of heat dissipation equipment such as air conditioners and ventilators, leading to continuous superimposed hidden operating costs.

Supercapacitor Energy-Saving System (Nearly Maintenance-Free)

Adopting the pure physical energy storage principle of electric double-layer supercapacitors, the system has no chemical loss or memory effect, adapting to the high-frequency shallow charge and discharge characteristics of elevator operation. The core module achieves a million-level cycle life. Under normal working conditions, no replacement of core energy storage units is required for 15–20 years. Without high-frequency wearing parts, only annual routine inspection is needed with extremely low maintenance costs. Meanwhile, it completely eliminates the continuous high-temperature heat source in the machine room, effectively reducing energy consumption of temperature control equipment and optimizing the machine room operating environment.

3.3 Full-Life Cycle Comprehensive Cost (5-Year Calculation)

Braking Resistor Solution: Low initial investment but high continuous cost. Multiple resistor replacements and line maintenance are required within 5 years, coupled with additional energy consumption of machine room air conditioning. It generates high comprehensive full-cycle expenditure with zero energy-saving revenue, belonging to a passive solution of "continuous cost and continuous energy consumption".

Supercapacitor Energy-Saving System: Relatively high one-time initial investment, nearly zero full-life cycle maintenance and remarkable sustainable energy-saving benefits. No frequent accessory replacement cost after equipment deployment, and electricity expenses are continuously reduced through stable energy-saving performance. Most high-frequency commercial elevator projects recover the initial investment within 1.5–2 years and achieve pure long-term profits, with far superior full-cycle cost performance than traditional braking resistor solutions.

4. Additional Values and Operational Differences

4.1 Equipment Safety and Machine Room Environment

The continuous heat dissipation of braking resistors leads to perennial high temperature and stuffiness in the machine room, accelerating the aging of elevator inverters, control cabinets and cables, increasing equipment failure rates, and bringing hidden dangers of high-temperature fire and line short circuit.

The supercapacitor system has no heat-generating energy-consuming components, completely eliminating high-temperature heat sources in the machine room. It optimizes the machine room operating environment, delays the aging of the elevator's overall electrical equipment, reduces elevator shutdown failure probability, and improves operational safety and stability.

4.2 Grid Adaptability

The braking resistor solution has no grid optimization capability, resulting in large instantaneous impact current, obvious grid load fluctuation and high peak power consumption during elevator start-stop.

The supercapacitor system suppresses instantaneous grid impact during elevator start-stop, realizes peak clipping and valley filling, stabilizes voltage fluctuation, reduces transformer peak load, and adapts to scenarios with tight grid load such as old communities, commercial complexes and office buildings.

5. Scenario Adaptation and Selection Conclusion

Priority for Traditional Braking Resistor Solution: Low-frequency use, idle old elevators, temporary transition equipment, scenarios with no requirements on energy consumption and operation cost, and equipment with service life less than 3 years.

Priority for Supercapacitor Energy-Saving System: Elevator clusters with high-frequency start-stop and year-round operation in office buildings, shopping malls, hotels, parks and high-rise residential buildings; projects pursuing low operation and maintenance, low energy consumption, high safety and green energy-saving renovation; scenarios requiring grid peak load reduction, equipment aging mitigation and annual high electricity cost control.

6. Overall Summary

Traditional braking resistors only meet the basic needs of elevator electrical voltage stabilization and equipment protection, with structural shortcomings including zero energy saving, machine room heat accumulation, frequent maintenance, high hidden energy consumption and accelerated equipment aging. They are only suitable for low-demand, short-term transition scenarios. With multiple core advantages including regenerative energy recovery and reuse, ultra-long maintenance-free life, machine room environment optimization and grid load optimization, the supercapacitor energy-saving system leads comprehensively in energy-saving benefits, full-cycle cost, equipment safety and operational stability, becoming the mainstream optimal solution for current elevator green energy-saving renovation, cost reduction and efficiency improvement, and low-carbon operation.