Spring is nowadays the best time for the grid and renewables. Low consumption as heating period is coming to and end, air conditioning is not required yet and the sun can be strong already providing lost if solar power output. I can imagine with a grid and a huge growth of solar generation that there are a myriad tripping stones that can upset the balance.

For areas utilizing hydro, spring tends to bring the strongest annual flows due to snow melt.

In the UK we're having one of the hottest springs on record. Spain and Portugal may be similar.