ENTSO-E defines a Bidding Zone as the largest geographical area where market participants can trade electricity without needing capacity allocation. The CACM Regulation introduced this concept to manage structural congestion across European electricity markets. Relevance to EACs is multifaceted: If you work in sustainability, bidding zones are worth understanding because they are a frequent presence in discourse around higher-precision boundaries for market-based Scope 2 instruments, specifically Guarantees of Origin (GOs) in Europe. The key idea within certain schemes, such as RE100, is to prioritise regulatory alignment and physical interconnectivity between regions - precise geographic matching via bidding zones is a highly adjacent topic to this discussion. When GO procurement aligns with the bidding zone where the electricity is actually bought and delivered, reporting a strong and credible claim via locally matched GOs easier. Tracking all of this happens across separate national registries, one per country, which gets messy quickly when you're operating across borders. Soldera pulls these into a single platform so you're not logging into five different registries to manage certificates.