If you’re comparing an APC Smart-UPS or Easy-UPS Online against a line-interactive unit, price and VA rating aren’t the only numbers that matter — the online UPS running cost over its working life can be significant for a business operating servers 24×7. Online (double-conversion) UPS systems are more expensive to run than line-interactive models because every watt of power is converted twice. This guide explains why, how to estimate the extra electricity cost before you buy, and when that cost is worth paying.
Why Online UPS Uses More Power Than Line-Interactive
A line-interactive UPS (like an APC Back-UPS or Back-UPS Pro) normally passes mains power straight through an AVR circuit to your load, and only switches to battery/inverter during an outage. An online UPS does the opposite: it continuously converts incoming AC to DC, charges the battery, then inverts it back to clean AC — all the time, even when mains supply is perfectly fine. This
Shop what this guide covers
- Which APC UPS for Servers & Server Racks?Load table, VA sizing and the genuine APC units we stock for it.
- APC Back-UPS — for home & small officeLine-interactive UPS for desktops, Wi-Fi routers, CCTV and billing machines.
- APC Smart-UPS & online UPSDouble-conversion, pure sine-wave power for servers, racks and critical loads.
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