Most renewable energy auctions prioritize price-only selection criteria to minimize procurement costs. However, some countries have introduced multi-criteria auction systems to pursue additional policy goals beyond cost efficiency. This study investigates the trade-offs between these approaches by simulating the Korean solar PV auction market, where PV module carbon footprint certification is included as a non-price evaluation criterion. The findings show that multi-criteria auctions significantly increase the adoption of low-carbon PV modules and reduce overall carbon emissions, although total support costs also rise compared to price-only auctions. The paper further discusses whether such auction mechanisms represent the most cost-efficient pathway for achieving carbon reduction goals relative to alternative policy instruments.