Motor VFD Installation Payback Calculator
Estimate the financial case for adding a variable frequency drive by comparing baseline motor input power with a proposed variable-speed operating profile.
Estimate VFD savings
VFD economics
How VFD payback is calculated
The baseline input represents electrical power consumed without the proposed drive scenario. The proposed motor-side power is adjusted for the VFD's stated efficiency to estimate power drawn at the electrical supply.
VFD supply power = Proposed motor-side power ÷ VFD efficiency
Annual energy saving = (Baseline power − VFD supply power) × Savings hours
The calculator then multiplies the annual energy saving by the entered electricity price and adds annual maintenance savings.
Why the savings-hours input matters
Many variable-load applications do not operate at the reduced operating condition all year. Using a percentage of annual hours allows you to model a more realistic duty profile rather than assuming the VFD produces maximum savings continuously.
Application caution
VFD energy savings depend heavily on what the driven equipment actually does when speed changes. A user-entered proposed motor-side power should therefore come from a credible operating model, field measurement or equipment information rather than an assumed percentage reduction.
Not included
- VFD purchase incentives or rebates.
- Financing costs and taxes.
- Downtime or commissioning costs beyond the project cost input.
- Motor derating, harmonic effects or control-system interactions.
FAQs
Does installing a VFD always save energy?
No. The economic benefit depends on the load profile, control method, speed requirement and actual proposed power.
Why include drive efficiency?
A VFD has its own conversion losses, so the electrical input should not simply equal the motor-side power.
Can the proposed power be zero?
Yes mathematically, although a zero-power operating condition normally represents no useful load and should be checked before using it as a project case.
Is payback a guarantee?
No. It is a simple estimate using the assumptions supplied.