Figures of Merit for Wind and Solar PV Integration in Electricity Grids

In future electrical grids, high levels of Variable Renewable Energy (VRE) penetration including solar photovoltaics (PV) and wind energy is expected. This poses a challenge in system operation and planning especially in balancing electricity demand and supply. This paper examines figures of merit for wind and solar integration in electricity grids. Quantitative tools such as load duration curves, correlation analyses, and the Fourier transform were used to study the intermittency/variability of wind and solar PV power. Time series data on power production from the European Network of Transmission System Operators for Electricity (ENTSO-E), and Réseau de Transport d'Électricité (RTE) were used for the analyses. The analyses illustrate that despite the valuable amount of energy that can be obtained from wind and solar PV, these energy sources cannot be used as baseload power supply. Solar PV power is available for approximately 50% of the time year-round. Wind power output on the other hand can reach very small magnitudes of just a few megawatts several times in a year. More to that, wind is positively correlated over long distances, even exceeding 3000 km and aggregating wind fleets over a large geographic area might not guarantee continuous availability of wind power. Nonetheless, these sources can still be integrated in electricity grids in high proportions, provided intermittency mitigation options such as energy storage, curtailment, and demand-response are implemented