Simeunovic, JelenaSchubnel, BaptisteAlet, Pierre-JeanCarrillo, Rafael E.2022-04-112022-04-112022-04-112022-04-0110.1109/TSTE.2021.3125200https://infoscience.epfl.ch/handle/20.500.14299/186964WOS:000772458800053Accurate forecasting of solar power generation with fine temporal and spatial resolution is vital for the operation of the power grid. However, state-of-the-art approaches that combine machinelearning with numerical weather predictions (NWP) have coarse resolution. In this paper, we take a graph signal processing perspective and model multi-site photovoltaic (PV) production time series as signals on a graph to capture their spatio-temporal dependencies and achieve higher spatial and temporal resolution forecasts. We present two novel graph neural network models for deterministic multi-site PV forecasting dubbed the graph-convolutional long short term memory (GCLSTM) and the graph-convolutional transformer (GCTrafo) models. These methods rely solely on production data and exploit the intuition that PV systems provide a dense network of virtual weather stations. The proposed methods were evaluated in two data sets for an entire year: 1) production data from 304 real PV systems, and 2) simulated production of 1000 PV systems, both distributed over Switzerland. The proposed models outperform state-of-the-art multi-site forecasting methods for prediction horizons of six hours ahead. Furthermore, the proposed models outperform state-of-the-art single-site methods with NWP as inputs on horizons up to four hours ahead.Green & Sustainable Science & TechnologyEnergy & FuelsEngineering, Electrical & ElectronicScience & Technology - Other TopicsEnergy & FuelsEngineeringforecastingconvolutionpredictive modelsproductionweather forecastingcorrelationdata modelsphotovoltaic systemsforecastingmachine learninggraph signal processinggraph neural networkstext::journal::journal article::research article