What goes into UPS TCO
UPS total cost of ownership has four primary lines: capital cost (the unit plus installation), energy cost over the operating life, scheduled maintenance (vendor PM contracts and parts), and battery replacement (typically every 3–7 years depending on chemistry and room temperature). This calculator computes all four, applies present-value discounting at your cost of capital, and reports a single horizon-aligned NPV.
Why energy dominates
A 40 kVA UPS at 50% load and 0.9 PF puts roughly 18 kW through the unit. At 94% efficiency, the UPS dissipates about 1.1 kW continuously — which adds up to ~10 MWh/year. At $0.18/kWh, that is ~$1,700 every year, every year. Over a 10-year horizon (even at 6% discount), it is ~$12,500 in NPV — often greater than the CapEx of a small UPS.
Battery economics
VRLA batteries at 5-year design life cost roughly 15–25% of the UPS CapEx to replace. In a 10-year horizon you typically pay for one replacement; in 15 years, two. LiFePO4 packs cost more upfront but typically last 10–15 years — saving the second replacement and the associated dispatch cost. This calculator's default assumes one replacement event for every batteryLifeYears elapsed in the horizon.
Discount rate
For SMB customers without a published WACC, 6–10% is a reasonable proxy. Higher-growth businesses with limited access to capital can be at 12–18%. The discount rate matters disproportionately for long horizons — a 15% rate compounds aggressively and tilts the calculation in favour of efficiency at the time of purchase.