Home backup systems are often described in terms of kilowatt-hours — how long they can power your home. But a specification that rarely gets enough attention is transfer time: the gap between when grid power fails and when backup power takes over. That number matters more than most homeowners realize.
The Problem With "Backup Power"
Traditional home backup systems — including most first-generation home battery products — use an automatic transfer switch (ATS) that must detect a grid failure, physically switch the power source, and re-energize the circuits. This process typically takes 20–200 milliseconds. Some systems take longer.
That gap is invisible to the human eye. You won’t see the lights flicker. But sensitive electronic devices notice it acutely.
A computer that experiences even a 50ms power interruption will typically restart. A smart home hub may lose its Wi-Fi connection and take minutes to reconnect. Digital clocks reset. In-progress transactions on point-of-sale terminals can fail. Medical devices that rely on continuous power — oxygen concentrators, infusion pumps, certain CPAP machines — may alarm or momentarily interrupt therapy during longer transfer gaps.
UPS-Class Protection at Home Scale
Uninterruptible power supplies (UPS) are standard equipment in data centers and hospitals precisely because they eliminate the transfer gap. They work by continuously running loads through an inverter powered by batteries, keeping the inverter hot and ready. When grid power fails, nothing switches — the inverter was already powering the load. Transfer time is effectively zero.
Until recently, UPS-class transfer protection at whole-home scale was prohibitively expensive. The inverter technology required to run a 200-amp residential service continuously through an inverter was simply too costly and inefficient for residential use.
Kora’s Smart Panel uses a different approach: a hybrid online-interactive topology that maintains a hot standby inverter synchronized with the grid, allowing switchover in under 20 milliseconds — fast enough that the vast majority of sensitive electronics never experience an interruption. Your clocks don’t reset. Your computers don’t reboot. Your gaming session doesn’t disconnect.
Why 20ms Is the Magic Number
The tolerance threshold for most modern electronics is defined by the ITI (ITIC) curve, an industry standard established by the Information Technology Industry Council. Devices designed to this standard will tolerate power interruptions of up to 20ms without any disruption. The vast majority of consumer electronics, smart home devices, and home medical equipment are designed to this threshold or better.
At 20ms transfer time, Kora sits right at the boundary that protects essentially all residential electronics. At 50ms — the transfer time of a fast ATS — a meaningful fraction of sensitive devices will experience disruption. At 100ms or longer, you’ll notice it in computers, clocks, and smart home devices throughout your house.
The Medical Device Case
For households with members who depend on home medical equipment, transfer time is not an abstract specification — it’s a health consideration. Oxygen concentrators draw 150–600 watts continuously and are sensitive to power interruptions. Home dialysis machines run multi-hour cycles that can be disrupted by power gaps. CPAP and BiPAP machines may alarm on brief interruptions, waking users at night.
Traditional generator backup fails the medical device test because most generators take 10–30 seconds to start and transfer — an eternity for equipment that expects continuous power. Even fast ATS systems with 50–100ms transfer times can trigger equipment alarms.
With sub-20ms transfer, Kora provides the same class of protection that hospitals use for critical care equipment. For families with medical needs, this specification can be the deciding factor.
The Home Office Case
The rise of remote work has made home power reliability a professional issue. A dropped video conference call during a client presentation, a corrupted file saved during a power event, or a lost VPN connection during a critical security update are not just inconveniences — they are professional liabilities.
UPS devices on individual computers are common in home offices, but they add cost, require maintenance, and don’t protect the router, modem, and other network infrastructure that the computer depends on. A whole-home sub-20ms backup system protects every device simultaneously without requiring individual UPS units at each workstation.
The EV Charging Case
Level 2 EV chargers draw 7–19 kilowatts — a significant portion of a home’s total load. Many EV charging sessions happen overnight, and most EV chargers are designed to resume automatically after a brief power interruption without requiring user intervention.
However, some vehicles — particularly certain European EVs — will not restart charging after any interruption without the owner physically going to the vehicle and re-initiating the session. For an owner who relies on a full charge before a morning commute, a 3am power blip that stops charging can mean arriving at work with a half-charged vehicle.
With sub-20ms transfer, the EV charger doesn’t see an interruption. The charging session continues through a grid outage as long as sufficient stored energy is available.
The Engineering Behind It
Kora’s fast transfer time comes from the integration of the panel and inverter in a single unit. Traditional systems use a separate battery inverter connected to the main panel through an external transfer switch. The communication between these components introduces latency. Kora eliminates this by integrating the bidirectional inverter directly into the Smart Panel’s bus architecture, reducing the switching path to a single set of solid-state devices that operate in microseconds.
The practical result is a system that monitors grid power at 10,000 times per second, detects a failure event within one AC cycle, and completes the switch to battery power in less than half the time that most competing systems take to even detect the outage.
Zero-Gap in Practice
Kora customers consistently report the same experience during their first real outage: they didn’t notice it. The app records the event — timestamp, duration, circuits affected — but the only sign during the event was that the usual ambient hum of refrigerators and HVAC units continued without interruption while neighbors’ homes went dark.
That’s zero-gap power in practice. Not "backup power that kicks in quickly." Power that simply never stopped.