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Reasons for Heat Generation in Photovoltaic Inverters and the Hazards of Insufficient Cooling
Photovoltaic (PV) inverters are the core components of solar power generation systems. They convert direct current (DC) generated by PV modules into alternating current (AC). In this process, power devices (such as IGBTs and MOSFETs), inductors, capacitors, and transformers all produce heat.
1.Three Main Sources of Heat
More than 90% of the heat in inverters comes from three key components, each with clear theoretical support and measured data:
1.1 Power Semiconductors (IGBT/MOSFET): The primary heat source, accounting for over 70%.
IGBTs (Insulated Gate Bipolar Transistors) handle high-frequency switching for AC/DC conversion. Due to material limits, their energy conversion efficiency is below 100%, and the unconverted energy becomes heat (switching and conduction losses).
Typical overall inverter efficiency is 95%–98%, but local efficiency of power semiconductors is lower (90%–95%) because IGBTs endure high voltage and current, causing switching losses.
Example: A 200 kW string inverter with eight 25 kW IGBT modules. At 97% efficiency, heat loss per module is 0.75 kW, totaling 6 kW. Without cooling, IGBT temperature can rise from ambient to 140°C within 15 minutes, exceeding the 120°C safety limit.
1.2 Reactors/Inductors: Electromagnetic heat sources, 10%–15% of total.
Reactors (DC and AC) filter current harmonics and stabilize grid voltage. Heat comes from copper loss and iron loss. Copper loss results from current passing through the coil resistance (60–70% of total), while iron loss comes from hysteresis and eddy current losses in the magnetic core (30–40%).
Example: An 800 A AC reactor with 0.01 Ω resistance produces 6.4 kW copper loss and over 8 kW total with iron loss.
1.3 Filter Capacitors and Auxiliary Circuits: Minor heat sources, ~8%.
Filter capacitors (electrolytic/film) smooth voltage ripple but produce dielectric loss during high-frequency charge/discharge (~5%). Auxiliary circuits (MCUs, programmable chips) contribute ~3%. Though small, they raise temperatures in the sealed inverter.
2.Hazards of Insufficient Cooling
PV inverters are mostly installed outdoors (on rooftops, ground-based power stations), and the surface temperature of the equipment can exceed 60℃ in summer. Extreme environments amplify the hazards of insufficient heat dissipation:
2.1 Sharp Drop in Power Generation Efficiency
High temperatures trigger the over-temperature protection of IGBTs, which automatically reduce the switching frequency or limit output power—directly reducing power generation.
Real Case: A distributed PV power station (with an installed capacity of 1MW, using 10 units of 50kW string inverters) experienced a noon ambient temperature of 45℃ in summer 2023. The internal temperature of the inverter rose to 68℃, and the output power of each inverter dropped from 50kW to 42kW (a 16% attenuation), resulting in a significant reduction in power generation.
2.2 Shortened Service Life of Core Components
Electrolytic capacitors are the “service life bottleneck” of inverters, and their service life is strictly negatively correlated with operating temperature—the higher the temperature, the shorter the service life:
Service Life Comparison:
At 105℃: Approximately 2000 hours
At 85℃: Approximately 8000 hours
At 70℃: Extendable to 20000 hours
Real Case: A ground-based power station (with an installed capacity of 50MW, using 200 units of 250kW centralized inverters) had its heat sinks clogged with dust due to strong winds in the desert area, which was not cleaned in a timely manner. As a result, the operating temperature of the electrolytic capacitors was maintained at 92℃ for a long time. Among the inverters originally designed with a 10-year service life, 30 units suffered capacitor breakdowns after only 3 years.
2.3 Vicious Cycle of the Heat Dissipation System
If active heat dissipation equipment (such as fans and air conditioners) is relied on, high temperatures will cause the heat dissipation system to operate at full load, further consuming electrical energy and forming a cycle of “high temperature → heat dissipation power consumption → lower efficiency”.
2.4 Occurrence of Safety Accidents
Long-term high temperatures cause aging of insulation materials inside the inverter and detachment of solder joints. In severe cases, it may lead to the burnout of IGBTs, capacitor breakdowns, and even ignite surrounding cables and PV modules.
II. Types of Heatsinks for PV Inverters and Application Cases
(1) Extrusion Heat Sink
Structure: Made from 6063 or 6061 aluminum alloy by extrusion, with continuous parallel fins. Surface anodizing enhances radiation and corrosion resistance.
Advantages: Lowest cost, high production efficiency, light weight, high reliability, and easy installation—suitable for household scenarios.
Suitable Inverter Type: Household/small commercial string inverters with power < 30kW (e.g., household rooftop PV, balcony PV).
Real Application Case:
Equipment Model: Sungrow SG15KTL-M (15kW household inverter)
Heat Dissipation Design: The heat sink base plate is 280×160×12mm, with 42 fins (each 35mm in height);
Test Data: At an ambient temperature of 25℃, the IGBT junction temperature is 78℃; even when the ambient temperature rises to 40℃, the junction temperature is still controlled at 95℃ (below the 110℃ protection threshold).
- Die Casting Heat Sink
Structure: Made from ADC12 or A380 aluminum alloy via high-pressure die casting. Enables complex 3D structures and embedded copper sleeves/heat pipes.
Advantages: High design flexibility (capable of high fin density and special-shaped structures such as curved surfaces or needle-shaped fins), surface sandblasting and anodization, IP65 protection rating (dustproof and waterproof), and can also serve as the inverter housing (with impact resistance and salt spray resistance). It combines heat dissipation and outdoor protection functions—suitable for outdoor scenarios with heavy rain and high humidity.
Suitable Inverter Type: Outdoor commercial string inverters with power ranging from 30kW to 100kW (e.g., factory rooftops, commercial complexes, gas station PV).
Real Application Case:
Equipment Model: Huawei SUN2000-50KTL-C1 (50kW commercial inverter)
Heat Dissipation Design: The die-cast housing is 450×320×80mm, with 200 needle-shaped fins (2mm in diameter, 55mm in height), integrated with 2 units of 60mm silent fans;
Measured Effect: At an ambient temperature of 45℃ and a gentle wind (1m/s), the IGBT temperature is 92℃; after 1000 hours of salt spray testing (5% NaCl solution), there is no corrosion on the surface, and the heat dissipation performance does not attenuate.
(3) Skived Fin Heat Sink
Structure: Thin fins are skived directly from a solid aluminum or copper base, forming a monolithic structure with no contact resistance.
Advantages: Large fin aspect ratio, extremely thin fin thickness (less than 0.3mm), high density, and a heat dissipation area 30%-50% larger than that of extruded heat sinks. It is suitable for narrow spaces and balances small size and high efficiency.
Suitable Inverter Type: Inverters with power ranging from 50kW to 100kW and narrow installation spaces (e.g., rooftop container PV, compact energy storage inverters, integrated charger-inverters).
Real Application Case:
Equipment Model: Ginlong Technologies GW80KTL-H
Heat Dissipation Design: The skived fin base plate is 220×180×10mm, with fins 45mm in height and 1.5mm in spacing;
Measured Effect: At an ambient temperature of 55℃ and a wind speed of 2.5m/s, the maximum heat flux density is 12W/cm², and the IGBT temperature is 105℃; the overall volume is 25% smaller than that of die-cast heat sinks of the same power, making it suitable for scenarios with limited rooftop load-bearing capacity.
(4) Heat Pipe Heat Sink
Structure: Copper heat pipes embedded in baseplate transfer heat via phase‑change (evaporation/condensation).
Advantages: Extremely high equivalent thermal conductivity (up to several thousand to tens of thousands of W/m·K), fast thermal response speed, excellent temperature uniformity, which can significantly reduce the thermal resistance of the heat sink, and enable long-distance heat transfer and special-shaped structure design. It solves the problem of uneven hot spots in multi-IGBT modules and has low maintenance costs.
Suitable Inverter Type: Medium-sized ground-based power station string/centralized inverters with power ranging from 100kW to 500kW (e.g., agrivoltaic systems, fishery-solar hybrid systems, county-level PV power stations).
Real Application Case:
Equipment Model: GoodWe GW100K-MT (100kW medium-power inverter)
Heat Dissipation Design: The base plate is 350×250×15mm, with 6 built-in 8mm copper heat pipes, matched with aluminum fins (heat dissipation area of 1.2㎡), and assisted by 1 unit of 120mm high-speed fan;
Measured Effect: At an ambient temperature of 50℃ and a wind speed of 3m/s, the junction temperature is controlled at 103℃ (12℃ lower than that of traditional aluminum profile heat sinks); after 1000 hours of continuous operation, the heat pipes show no performance attenuation.
(5) Liquid Cold Plate Heat Sink
Structure: The inverter module is directly installed on a metal plate (usually aluminum or copper) with built-in flow channels. The cooling liquid (a mixture of deionized water and ethylene glycol) flows through complex flow channels (such as parallel flow channels, serpentine flow channels, and pin-fin microchannels) driven by a pump, and efficiently dissipates heat through convective heat transfer.
Advantages: Extremely high heat dissipation efficiency, large power density, extremely low thermal resistance, precise temperature control, and good temperature uniformity—suitable for high-temperature and high-power scenarios.
Suitable Inverter Type: Large-scale ground-based power station centralized inverters with power > 500kW (e.g., northwest desert PV bases, plain large-scale power stations, UHV-supported PV projects).
Real Application Case:
Equipment Model: Jinzhi Technology GNSS-2500K (2500kW centralized inverter)
Heat Dissipation Design: The liquid-cooled plate is made of 6-series aluminum, with internal microchannels of 1mm×3mm, a circulation flow rate of 50L/min, and matched with an air-cooled heat exchanger;
Measured Effect: At an ambient temperature of 40℃ and full-load operation, the IGBT temperature is stably maintained at 88℃, and the power consumption of the heat dissipation system accounts for only 2% of the total power consumption (compared to 8% for traditional air-cooled systems); after 1 year of continuous operation, the conductivity of the cooling liquid remains < 5μS/cm (meeting industry standards).
III. Recommended Heatsink Selection Table
To help you quickly find the right heat sink for your equipment, we have compiled the following recommended selection table for reference:
| Inverter Type | Power Range | Typical Application Scenarios | Recommended Heat Sink Type | Core Advantages (Including Cost/Protection/Applicability) |
| Household Type | < 30kW | Household rooftops, balcony PV, small guesthouses | Extrusion Heat Sink | Extremely low cost, no noise from natural convection, light weight, easy installation—suitable for household scenarios. |
| Commercial Outdoor Type | 30-100kW | Factory rooftops, commercial complexes, gas stations | Die Casting Heat Sink (with fan) | IP65 protection (resistant to rainwater/salt spray), high fin density, moderate cost—suitable for harsh outdoor environments. |
| Medium-Sized Ground-Based PS Type | 100-500kW | Agrivoltaic systems, fishery-solar hybrid systems, county-level power stations | Heat Pipe Heat Sink | Good temperature uniformity (base plate temperature difference < 5℃), solves hot spot issues, low maintenance cost—suitable for multi-module designs. |
| Large-Sized Ground-Based PS Type | > 500kW | Deserts, plain bases, UHV projects | Liquid Cold Plate Heat Sink | Extremely high heat dissipation efficiency, supports full-power output, low proportion of heat dissipation power consumption—suitable for high-temperature and high-power scenarios. |
| Compact Space Type | 50-100kW | Rooftop containers, integrated energy storage inverters | Skived Fin Heat Sink | Compact volume (30% smaller than die-cast type), large heat dissipation area—suitable for narrow installation spaces. |
| High Heat Flux Special Type | 80-200kW | High-frequency inverters, energy storage converters (PCS) | Combined Heat Sink (Skived Fin + Heat Pipe) | Copes with local high heat flux (> 20W/cm²), balances compactness and efficiency—suitable for high-density component layouts. |
This table can be used as a reference for preliminary selection. For actual selection, it is recommended to conduct detailed thermal simulation and experimental verification based on specific operating parameters. We are a heat sink manufacturer based in Guangdong, China, providing customized design services—with a focus on high-power heat dissipation solutions. We can also conduct thermal simulations based on the specificities of actual application scenarios to determine fin sizes, the shape of internal flow channels in liquid-cooled plates, etc. Customers with relevant needs are welcome to consult us at any time, and our engineering team will provide you with professional technical support.
