In harsh sunlight, the Pokémon's Sp. Atk stat is boosted by 50%, but it loses 1/8 of its max HP at the end of every turn.
Solar Power (Japanese: サンパワーSun Power) is an Ability introduced in Generation IV.
Effect
In battle
During harsh sunlight, Solar Power increases the Pokémon's Special Attack by 1.5×, but the Pokémon loses 1/8 of its maximum HP at the end of each turn, if harsh sunlight does not end that turn.
In Explorers of Time, Darkness and Sky, Solar Power increases the Pokémon's Special Attack by one stage in sunny weather. The Pokémon loses 3HP every 9-10 turns, but does not prevent the natural HP recovery.
In Pokémon Super Mystery Dungeon, Solar Power sharply boosts the Pokémon's Special Attack when the weather is sunny or in harsh sunlight. The Pokémon also loses 1 HP every 10 turns and is unable to recover HP naturally.
During Sunny weather or in Extremely Harsh Sunlight, the Pokémon's Sp. Atk goes up sharply, but the Pokémon can't restore its HP naturally and keeps taking damage.