negativepower

Negative power is not a single formal concept with a universal definition, but a term used in several disciplines to describe a flow of energy in the opposite direction to a reference convention. In electrical engineering and energy systems, negative power usually refers to power that leaves a device or network rather than consuming it.

In circuit theory, instantaneous power is defined as P = v(t) i(t). Under the standard passive sign convention, P > 0 means the element absorbs or consumes power, while P < 0 indicates the element delivers power to the rest of the circuit. Thus negative power indicates energy flow from the element to the source or to the grid. Examples include a solar inverter exporting energy, regenerative braking feeding energy back into a drive train and then to the grid, or a battery discharging into a load when described from the device’s point of view.

In broader energy systems, negative power can occur during periods of excess generation or when storage devices feed energy back during low demand; net metering and grid-tied inverters treat negative power as generation rather than consumption.

In mathematics, the term negative power is less common and often replaced by negative exponent, where x^-n equals 1/x^n. The phrase may appear informally in discussions of reciprocal relations or power laws, but is not standard mathematical terminology.

See also: Power (physics), Electrical power, Active power, Reactive power, Apparent power, Inverter, Net metering.