SolarSquare is India's #1 residential rooftop solar D2C brand, and ERPNext v15 is the system of record for 400+ users across supply chain, finance, and warehouse operations — integrated with banking and payment gateway APIs, an AMC (Annual Maintenance Contract) lifecycle automation module, and a custom Order Management System driving end-to-end transactions across both B2B and B2C channels. When the business committed to a 50,000+ installation milestone, our ERPNext instance — a single EC2 monolith — started cracking. This talk is about that migration: splitting the monolith into a Web Auto Scaling Group, a dedicated Worker EC2, ElastiCache Redis with TLS, RDS MariaDB (read/write split), Lambda, and S3 storage.