The European energy landscape has evolved to include the concept of energy communities in most countries. In order to fully benefit the entire value chain, from consumers to producers, particularly including renewables, integration with electricity markets should be considered and further explored. This paper presents the results of methods and simulations conducted within the scope of the TRADERES project, which aims to develop "New Markets Design & Models for 100% Renewable Power Systems". The focus will be on the operational context of energy communities in Portugal, including integration with MIBEL (Iberian Electricity Market). The implemented methodology will involve the following steps: - Energy management of an energy community, considering available renewable-based generation, storage, and flexibility; - Negotiation of energy between energy communities; - Negotiation of energy from communities in MIBEL; - Updating energy management in each community according to market results. The numerical case study will consider actual bidding scenarios in MIBEL, with real bids and prices. Various scenarios will be discussed at the community level within a specific market context.