In the context of the 2009 debate on reforming the Italian market, a realistic agent-based computational
model of the day-ahead market session of the Italian wholesale electricity market is simulated to compare
market performances between uniform-price and pay-as-bid clearing mechanisms. An empirical validation
of computational results at a macro-level is performed to test for accuracy of simulated outcomes with
historical ones. The level of prices are accurately reproduced except for few peak hours. As far as concerns
pay-as-bid auction, the computational experiments point out that it results in higher market prices than the
uniform-price auction. In the pay-as-bid mechanism, sellers’ endeavours to maximize their profits are more
costly thus leading to higher price levels.
