Solar Lattice

Concept

Reactive power

ID
concept:reactive-power
IRI
https://solarlattice.org/kb/concept/reactive-power
Status
active
Also known as
kvar, VAr, Q
Category
Grid
Concept kind
electrical

Reactive power, written Q and measured in VAr, is the imaginary part of complex apparent power, while active power in watts is the real part; together they form the power triangle. Injecting reactive power raises voltage at the connection point and absorbing it lowers voltage, so an inverter running at an absorbing power factor can offset the voltage rise caused by exporting real power. In constant VAr mode the inverter generates or absorbs a fixed amount of reactive power on command, much like utility switched capacitors; if the inverter's MVA rating would be exceeded, reactive output is capped without cutting active power. Large PV plants may be told by grid operators to absorb or supply reactive power at the grid connection point to help regulate voltage and stabilize the grid. Inverters and plant controllers expose reactive power as both a measured value and a setpoint, for example manual VAr setpoints, maximum reactive power limits, and Volt-VAr curve points set in percent under each grid code setting.

Claims

related_to

c1 drafted · lead Apparent power

Reactive power is the imaginary part of complex apparent power.

c2 drafted · lead Active power

Active power is the real part and reactive power the imaginary part of apparent power.

c3 verified · fact Power factor

Changing the power factor setpoint changes the inverter's reactive power output.

verified by: review-workflowverified on: 2026-10-24

c5 drafted · lead Constant reactive power mode

c6 drafted · lead Constant power factor mode

c7 drafted · lead Volt-VAr

Volt-VAr curve points are set as reactive power percentages; one vendor limits output to 60% of nameplate.

review note: support check: partial - Q(U) points as percentages and 60% nameplate limit are stated, but the 60% limit is not attributed to one vendor and curve-point wording is implicit.

explains

c4 drafted · lead Voltage rise

Injecting reactive power raises voltage at the point of injection; absorbing it lowers voltage.

Referenced by

Data