The natural variability of weather makes long-term planning an essential prerequisite for reliable electricity systems that are based on weather-dependent wind and solar power. A new study involving CMCC researcher Enrico Antonini finds that 40 years of weather data are required to plan highly reliable systems, although similar levels of reliability can be achieved with 15 years of weather data when traditional dispatchable generation is incorporated. 

The road to a net-zero emissions world requires rigorous planning of renewable energy installations and detailed knowledge of weather conditions spanning over decades, particularly when it comes to wind and solar energy development.

New research reveals that ensuring the reliability of wind- and solar-based systems will require using considerably more weather data in system planning than is the current practice. This was done by investigating how the number of years of weather data affects reliability when designing electricity systems that rely on wind, solar, and energy storage.

“We found that nearly 40 years of weather data are required to plan highly reliable systems that experience zero lost load when tested over 10 out-of-sample years,” says co-author of the study and CMCC researcher Enrico Antonini. “In comparison, this same degree of reliability could also be attained with 15 years of weather data, when adding dispatchable generation (natural gas) to supply up to 5% of electricity demand.”

The lost load during system operation for each studied scenario (panel a) and the system levelized cost of electricity (LCOE) from the original planned systems (panel b). Source: Ruggles et al. 2024

The study reveals that using more years of weather data during planning of solar- and wind-based systems decreases lost load (i.e. unmet demand), but also increases the cost of the electricity system such that the marginal benefits of planning with more years of data diminishes.

Previous studies in the long-term system planning space, where capacity expansion models are applicable, largely neglected an analysis of how reliability improves as models are optimized over longer periods of time. However, this new study assesses the trade-offs among cost, asset capacities, and reliability of idealized solar- and wind-based electricity systems, as well as the incremental cost of increasing reliability as a function of the number of years of weather data used in electricity system planning.

“As we transition to deeply decarbonized electricity systems, the increasing reliance on wind and solar power will make energy generation more sensitive to weather patterns,” says Antonini. “Unlike traditional power plants, which provide steady output, renewable sources like wind and solar fluctuate due to changing meteorological conditions. This growing dependence on variable weather will necessitate a significant transformation in the way we design, manage, and operate electricity grids, particularly by making greater use of meteorological data to improve system resilience.”

For more information:

Tyler H. Ruggles, Edgar Virgüez, Natasha Reich, Jacqueline Dowling, Hannah Bloomfield, Enrico G.A. Antonini, Steven J. Davis, Nathan S. Lewis, Ken Caldeira,

Planning reliable wind- and solar-based electricity systems, Advances in Applied Energy, Volume 15, 2024, 100185, ISSN 2666-7924, https://doi.org/10.1016/j.adapen.2024.100185