The electricity retail industry is becoming increasingly competitive, and retailers are looking for innovative ways to attract and retain customers. One potential strategy is to offer retail packages that include electricity pricing based on the single pendulum equation (SPE). This article discusses the design of a retail package system for electricity retailers based on the SPE. The system utilizes real-time data on electricity supply and demand to create a dynamic pricing system that adjusts prices based on changes in the market. This article present the single pendulum equation model and data obtained from Residential Electricity End-use Demand Dataset of Costa Rica (REEDD-CR). It outlines the key steps in designing the system, including gathering data on electricity supply and demand patterns, creating a pricing algorithm based on the single pendulum equation, and integrating the system with billing and customer management systems. The article also emphasizes the importance of considering customer preferences and behavior in the design of the system. The study findings stated that single pendulum model has provided an evaluation time of 1.5s and price and demand value of 0.6. A well-designed dynamic pricing system based on the single pendulum equation has the potential to provide customers with cost savings and increased flexibility while allowing retailers to optimize their pricing strategies in a competitive market.