Film Capacitors Move Into the Mainstream

For decades the DC link of a power converter was built from aluminum electrolytic capacitors, chosen for their high capacitance per unit cost. In 2026 that default is changing. Metallized polypropylene film capacitors, once reserved for high-end and high-reliability designs, are moving into mainstream inverters, driven by electric vehicles, renewable energy and the demand for a longer product life. The reason is straightforward: a film capacitor has far lower equivalent series resistance, tolerates a much higher ripple current, self-heals a local breakdown and does not dry out, so it lasts far longer than the electrolytic it replaces.

Electric Mobility

The most visible driver is electric mobility. A traction inverter and an on-board charger both need a DC link that handles high ripple current at high temperature, and the film capacitor meets that need without the dry-out mechanism that limits an electrolytic. As 800 V vehicle platforms spread, the DC-link voltage class rises and film capacitors cover the range comfortably. The larger inverters and chargers also benefit from the low self-inductance of a screw-terminal film capacitor bolted to laminated busbars, which keeps the bus voltage clean at high current.

Solar and Storage

Solar string inverters and battery storage converters run outdoors for years, often at high ambient temperature, where an electrolytic would dry out and lose capacitance. A film capacitor is far more tolerant of heat, so its life is measured in decades rather than a few thousand hours, and that directly cuts maintenance and warranty cost. Analysts expect photovoltaic and storage to be among the fastest-growing film-capacitor segments through 2026 as manufacturers chase higher efficiency and longer life.

Industrial Drives

Industrial motor drives were the first volume market for the film DC link and remain a large one. Here the film capacitor earns its place through a combination of long life, low ESR and self-healing, and through the ability to replace an electrolytic bank with fewer parts and a simpler thermal design. A drive built around a film DC link has fewer wear-out components, which matters in continuous industrial duty.

Where Electrolytics Still Fit

Electrolytic capacitors remain cost-effective where capacitance per unit volume and low cost dominate and the ripple current is modest, such as in low-cost consumer supplies. The sensible approach is to choose the technology that minimises total system cost and lifetime risk, not to replace every electrolytic. The film capacitor earns its place where ripple current is high, the ambient is hot or the product must last, and that describes a growing share of power electronic designs.

What Changes for Designers

For a design team, moving to a film DC link changes the selection method. Capacitance is set by the allowable bus ripple, but the decisive check becomes the ripple current at the hot case temperature, and the placement and loop inductance become as important as the value. Sizing the part on ripple current rather than capacitance is the practical habit that gets the thermal design right, and it is a common source of early field failures when it is missed.

The Outlook

The direction is clear: film capacitors are becoming the default DC-Link part for high-reliability and high-ripple converters, while electrolytics remain appropriate for simple, cost-driven designs. Faratronic covers the full range with PCB and aluminum-case DC-Link capacitors, snubbers and motor capacitors, and BeiLuo supplies them with stock, documentation and FAE support for drive, solar and appliance manufacturers.

What to Watch in 2026

Three things are worth watching through 2026. First, the continued move to film DC links in mainstream industrial drives, where the ripple-current advantage lowers field-failure rates. Second, the rise of 125 C automotive-grade film capacitors as 800 V platforms spread, which will push both the film and the packaging further. Third, the growing importance of the connection and the layout, because a low-ESR capacitor on a long lead delivers little of its benefit, and designers increasingly ask about loop inductance before choosing a part.

The Practical Effect for Designers

For a design team, the shift to film changes the selection method. Capacitance is set by the allowable bus ripple, but the ripple current at the hot case temperature becomes the deciding check, and placement becomes as important as value. Teams that adopt that method early avoid a DC link that runs hot or fails in the field, which is exactly the outcome a longer-life capacitor is meant to deliver.