Full Load hour is a measure of the degree of utilisation of a technical system.
Full load hours refer to the time for which a plant would have to be operated at nominal power in order to convert the same amount of electrical work as the plant has actually converted within a defined period of time, during which breaks in operation or partial load operation can also occur. The figure usually refers to a period of one calendar
year
A year is a unit of time based on how long it takes the Earth to orbit the Sun. In scientific use, the tropical year (approximately 365 Synodic day, solar days, 5 hours, 48 minutes, 45 seconds) and the sidereal year (about 20 minutes longer) ...
and is mainly applied to
power plants
A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid.
Many power ...
.
The annual utilisation rate or
capacity factor
The net capacity factor is the unitless ratio of actual electrical energy output over a given period of time to the theoretical maximum electrical energy output over that period. The theoretical maximum energy output of a given installation is def ...
derived from the number of full-load hours is the relative full-load utilisation in a year, i.e. the number of full-load hours divided by 8760 hours, the number of hours in a year with 365 days.
Description
Typically technical plants are not constantly operated at full load, but depending on various factors (see below) the system can be under a partial load. The total
work
Work may refer to:
* Work (human activity), intentional activity people perform to support themselves, others, or the community
** Manual labour, physical work done by humans
** House work, housework, or homemaking
** Working animal, an ani ...
converted by the plant in a year is therefore less than the maximum possible work in the same period.
The degree of utilisation of a technical plant can be expressed in full load hours if a nominal capacity can be specified and an adequate conversion from partial load operation to nominal load operation exists (e.g. on the basis of the amount of energy or material converted).
The number of full load hours of a plant varies from year to year due to different
technical inspection durations, power plant operating schedules,
maintenance
The technical meaning of maintenance involves functional checks, servicing, repairing or replacing of necessary devices, equipment, machinery, building infrastructure and supporting utilities in industrial, business, and residential installa ...
, unplanned disturbances and outages and due to different weather conditions, especially for
renewable energy
Renewable energy (also called green energy) is energy made from renewable resource, renewable natural resources that are replenished on a human lifetime, human timescale. The most widely used renewable energy types are solar energy, wind pow ...
sources.
The value must not be confused with
operating hours. These refer to the entire period of time during which the system has been operated and can
has been operated and may include periods of partial load operation.
Definition
The number of full load hours of a generator is calculated by dividing the (expected) annual energy output (e.g. in
kWh) by the nominal
power
Power may refer to:
Common meanings
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power, a type of energy
* Power (social and political), the ability to influence people or events
Math ...
of the generator (e.g. in kW or
kWp).
:
It indicates how many hours the plant would have run to achieve the same annual energy production if it had been running either at full load or otherwise have been completely inactive.
References
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Solar energy
Wind power
Energy measurement