# Installed capacity

Installed power is a term from the electricity industry. It marks the maximum power (the rated power ) of a power plant installed generators or in a country or a state installed total capacity of all power plants. It is given in watts and multiples such as megawatts (MW) or gigawatts (GW).

## meaning

Some power plants only work for hours or at times in partial load operation, which is why the average switch-on duration over a longer period of time, usually one year, must be known in order to calculate the energy generated. The realistic, average yield determined in this way is referred to as the standard energy capacity and is decisive for assessing the profitability of a system. In this context, it is usually specified as a unit of energy in watt hours or a multiple thereof.

The quotient of the actual generated energy E is , the standard capacity, and from the installed capacity over a time interval, usually a year given the maximum possible energy output E max is referred to as annual efficiency Q . This quotient Q is always between 0% and 100%:

${\ displaystyle Q = {\ frac {E _ {\ mathrm {is}}} {E _ {\ mathrm {max}}}}}$

Sometimes the annual degree of utilization is also specified in full load hours , which indicate the number of hours in the billing interval, assuming a constant decrease in power over time, with the value of the installed power.

If the nominal voltage is known, the installed power gives the maximum generated current and thus the necessary cross-section of the power cable when installing the system.

### example

Consider a wind power plant with a nominal output of 2 MW that produces 4.5 GWh of electrical energy over a year with 8760 hours and a total of 8000 operating hours  . The theoretical maximum annual production that cannot be achieved in practice is 8760 h × 2 MW = 17.52 GWh. A capacity factor of 25.68% or 2250 full load hours is calculated from the percentage of annual production in relation to the theoretical maximum production .

## restrictions

Only in the case of power plants operating at base load can the installed capacity be used to determine the annual energy output into the grid ( specified in GWh ). Here must at thermal power plants , the accruing own needs in the amount of five to ten percent and the losses due to revisions in the amount of ten to fifteen percent are considered. In the case of run-of-river power plants running at base load , losses due to weather-related low water levels , maintenance work or ice drifts must be included in the calculation.

In the case of power plants that are designed to cover peak loads , no conclusions can be drawn about the permanent yield from the installed capacity; some of them are only operated for a few minutes or hours per day, while others could technically contribute significantly more to the base load, but are only needed and switched on for peak loads. Pumped storage power plants also need electrical power in order to be “charged” for peak demand.

## Installed capacity in Germany

The power plant capacities that feed into the German grid are listed below. 11.6 GW of the listed 214.1 GW in 2019 come from power plants outside the electricity market . These power plants are provisionally closed, are in security readiness or serve the power reserve .

Net electricity generation capacity in 2014 and 2019
2014 2019
Energy source GW % GW %
Hard coal 26.9 14.7 23.7 11.1
Brown coal 20.9 11.4 21.2 9.9
Mineral oil products (2014 heating oil) 3.7 2.0 4.3 2.0
Natural gas (2014 gases) 22.5 12.3 29.4 13.7
Nuclear energy 12.1 6.6 9.5 4.4
water 14.4 7.8 14.6 6.8
Wind (onshore) 34.0 18.5 50.3 23.5
Wind (offshore) 0.6 0.3 5.4 2.5
Solar radiation energy (2014 photovoltaics) 37.4 20.4 42.3 19.8
Biomass 7.2 3.9 7.7 3.6
Others renewable 3.9 2.1 1.3 0.6
Not renewable 4.4 2.1
All in all 183.6 100 214.1 100

## Individual evidence

1. ↑ In 2002 the average of the German wind power plant park near the German North Sea coast was approx. 7500 operating hours per year, individual plants achieved up to 8000 operating hours. Proof: Electricity from wind energy for up to 8,000 hours per year . In: Innovations Report , November 19, 2002. Retrieved December 15, 2012.
2. a b Federal Network Agency: power plant list; As of March 7, 2019 (EEG systems evaluated as of December 31, 2017)