Smart Grids: Capacity Credit of Wave and Solar PV

Towards the development of Smart Energy Systems

The Executive Summary, Final Project Report and Project’s Final Presentation (ppt) can be downloaded here:


Executive Summary    Final Project Report   Final ppt



The aim of this project is to determine how new renewable energies, such as wave power and solar photovoltaics (PVs), can be included in the planning and operation of electricity systems as a substitute for conventional base-load and intermediate-load electricity generation.


A capacity credit has been associated with wind power in Denmark, but not with solar PV and wave power.

Provided that the capacity credit is the amount of thermal capacity that would be displaced by a variable renewable energy portfolio, it is the purpose of the project to find the capacity credit for three different scenarios in 2020, 2035 and 2050, including wind, wave and solar PV.

The results of the project can ultimately lead towards an improvement of existing rules and methods of system planning and system operation.




Project description

In Europe, there will be more and more electricity generated through renewable energy sources and the share of conventional power plants will decrease. More variable renewable energy sources partially imply that the need for reserve capacity will increase.

In Denmark, there is a need to examine whether the new renewable forms of production can be included in the planning of future energy systems. Today, both conventional power plants and wind turbines have a capacity value, which is included in long-term system and operational planning at (the Danish TSO, the Transmission System Operator).

New renewable energy production methods, such as wave power and solar photovoltaic (solar PV), are not represented by a capacity value today. For wave power, this is due to the fact that electricity production exists only pre-commercially. The reason why solar panels PV currently have a capacity credit of 0% is because solar energy is seen as a negative consumption.

While conventional power plants are aging, it is essential to get the capacity value of new technologies calculated and utilised. The parameter capacity credit or capacity value measures the contribution that variable renewable energy generation can make to system reliability.

This project addresses specifically the capacity credit of a renewable energy portfolio including solar PV, wind and wave energy.

Electricity generated by solar cells, which happens in the low voltage system, can both help to reduce transmission and distribution losses, and to add generation in the load side where consumption is highest. Solar PV panels are currently regarded as a negative consumption, and the control options that solar cells provide are not utilised system-wise.

Electricity generated by wave energy converters can increase the utilisation factor of an offshore wind farm and simultaneously minimise the percentage of time when there is no production, reduce peak production and smooth out the electricity produced especially at high wind speeds. Benefits that may create systemic synergies and increase the capacity credit of combined energy parks.

Waves and sun are natural resources and both, in the same way as wind, have their natural limits. Combined with wind, they also bring complementary benefits. An energy system consisting of a certain amount of wind, wave and solar energy is a more robust system than the wind-only system.

Any facility producing electricity and/or receiving money for regulating services is included in operational planning. For this, the plant’s production must be forecasted with reasonable accuracy. The capacity credit of power plants based on coal and gas are normally high. Wind energy also has a capacity credit above zero, of different values depending on its penetration. Based on this background, wave energy may also have a capacity credit above zero, since it is based on the same meteorological data than wind. The project will investigate how solar PV influences the capacity credit of a combined wave and wind energy system.

Ultimately, this project aims to answer the questions of whether variable renewable energy production can be included in the short-term, mid-term and long-term system planning of, how and with what weight.

Project partners are Consulting Engineer Julia F. Chozas, Wave Star A/S, Aalborg University and Danfoss Solar Inverters. Dansk Energi, who represents Danish Distribution Network companies, and act as external project advisors.

This project has been funded by, under the PSO ForskVE programme and under the Section of Smart Grids.

The project runs from January 2014 to June 2015.