however while numerical results can differ the main trends and effects observed are common to all system and penetration levels in the short term the electricity system is locked in with the existing generation mix and infrastructure and cannot adapt quickly to the introduction of the new technology on the contrary in the long term both the infrastructure and generation capacity can evolve and adapt to the new market conditions resulting from the introduction of the new generation capacity thus system costs are different if assessed in a shortterm perspective with numerous dynamic processes or in a longterm equilibrium perspective