Listed are terms applied in customer reports and studies.

Quantity | Full name | Measure unit | Definition |
---|---|---|---|

Lifetime | Project lifetime | a | Total lifespan/duration of the project (in years) |

DER | - | Distributed energy resources (DERs) are electricity-producing resources or controllable loads that are directly connected to a local distribution system or connected to a host facility within the local distribution system. |

Full name | Measure unit | Definition |
---|---|---|

Estimated life time | a (years) | Total time of system/technology during which it can technically perform/function before it must be replaced |

Operational Power | kW | Amount of electric or thermal generation capacity (rated values) |

Nominal capacity - maximum value | kW | Highest power allowed in operation |

Nominal capacity - minimum value | kW | Minimum power allowed in operation |

Conversion efficiency | % | Ratio between useful output of an energy conversion machine and the input, in energy terms |

Maximum (positive/negative) power gradient | 1/h | The time needed for a system to go from 0% to 100% power output (viceversa, when negative). 1/h means that the systems needs 1 hour to reach rated capacity, 0.5/h means 2 hours, 4/h means 15 minutes, etc. |

Self-discharging ratio | 1/d | The energy losses of a (heat/cold/electric) storage that occur independently from its operation, expressed as daily rate. 1/d means that the storage loses 100% of the stored energy per day, 0.5 means 50%, etc. |

Minimum SOC | % | An expression of the minimum energy of a storage system, as a percentage of its nominal capacity |

Roundtrip efficiency | % | Round-trip efficiency is the fraction of energy put into the storage that can be retrieved |

Heat loss | kW | The wasted heat or power |

Start-up wind speed | m/s | Rated (minimum) start-up speed of a wind turbine |

Rated wind speed | m/s | The wind speed at which the turbine can generate electricity at its maximum, or rated, capacity |

Inverter efficiency (Euro efficiency) | % | The "European Efficiency" is an averaged operating efficiency over a yearly power distribution corresponding to middle-Europe climate |

Quantity | Full name | Measure unit | Definition |
---|---|---|---|

CAPEX | Capital expenditures | € | Investment costs for building project-related assets. Those can be upfront costs (at project begin), as well as costs related to hardware substitution along the project lifetime |

OPEX | Operational expenditures | €/a | Opex means operational expenditure i.e. the expenses incurred yearly after the system/technology has been commissioned (e.g. fuel costs). This does not include replacement costs, which are part of the CAPEX |

Grants | € | Grants or funds available from state or government which do not have to be paid back | |

Debt term | a (years) | Pay back payment schedule over several months or years for the loan | |

ROI | Return on investment | % | On a single system:
$$ ROI = \frac{Rev - OPEX - \left( CAPEX - Res \right) } { CAPEX } \cdot \frac{1}{100} $$ When comparing two systems:$$ ROI = \frac{Rev_{S2} + Sav - \left( CAPEX_{S2} - Res_{S2} \right) } { CAPEX_{S2} } \cdot \frac{1}{100} $$ |

Break-even | a (years) | The year when the cumulative benefit (OPEX savings against reference case) exceeds the cumulative effort (CAPEX increment). ROI at break-even is 0 %. | |

Rev | Revenues | € | Profit earned from system operation (e.g PPA) |

Res | Residual Value | € | The residual value is the estimated value of a fixed asset at the end of its lease or at the end of its useful life or project lifetime |

Sav | Savings | € | Given two systems S1 and S2:
$$Sav = \left( OPEX_{S1} - OPEX_{S2} \right) + \left( CAPEX_{S1} - Res_{S1} \right) - Rev_{S1}$$ |

LCOE | €/kWh | The net present value of the unit-cost of electricity over the lifetime of a generating asset | |

Cash flow | € | Incomings and outgoings of cash, representing the operating activities of a system in a given time period | |

Net present value | € | The difference between the present value of cash inflows and the present value of cash outflows over a period of time | |

Inflation | % | The annualized percentage change in a general price index over time | |

Price change rate | % | The percentage change in a price between two periods | |

Internal interest rate | % | The internal rate of return is a discount rate that makes the net present value (NPV) of all cash flows from a particular project equal to zero | |

Equity share | % | A main source of finance for a project giving investors rights to vote, share profits and claim on assets |