INTERACTIVE WEB SERVICE FOR COMPARING ENERGY EFFICIENCY INVESTMENT PAYBACK PERIODS USING TYPESCRIPT, NEXT.JS, NESTJS AND PRISMA

Abstract

The article presents the results of the development and research of an interactive web service for automated comparative evaluation of investment payback periods in energy-efficient technologies. The relevance of the research is driven by the consequences of full-scale military aggression against Ukraine, which caused a crisis in critical infrastructure facilities and formed a strong demand for decentralized energy supply solutions (solar power plants, heat pumps, thermal modernization). The parameters of Ukrainian state and international financial support programs for 2025–2027 ("Energodim", "GreenDIM", "5-7-9%", UNDP, EIB) are systematized for three categories of consumers: homeowners, OSBB (condominium associations), and SMEs. The aim of the study is to increase the efficiency of investment decision-making by automating calculations of economic indicators. An extended mathematical model is proposed, which parameterizes the grant co-financing share, energy tariff growth rate, and discount rate for the simultaneous calculation of five key indicators: Payback Period ( ), Discounted Payback Period ( ), Net Present Value ( ), Internal Rate of Return ( ), and Profitability Index ( ). The design of a three-level C4 architecture, a relational ER data model with seven entities, and a declarative Prisma schema are described. Features of the full-stack implementation based on TypeScript, Next.js 14, NestJS 10, PostgreSQL, and the Recharts library are presented. Results of multi-level testing (38 tests, 87% code coverage) and calculation examples confirming a 1.7-fold reduction in payback period for OSBB with a 70% grant are provided. Limitations of the system and prospects for further development are identified, including integration with Open Banking APIs and the implementation of an LLM-based AI module.The article presents the results of the development and research of an interactive web service for automated comparative evaluation of investment payback periods in energy-efficient technologies. The relevance of the research is driven by the consequences of full-scale military aggression against Ukraine, which caused a crisis in critical infrastructure facilities and formed a strong demand for decentralized energy supply solutions (solar power plants, heat pumps, thermal modernization). The parameters of Ukrainian state and international financial support programs for 2025–2027 ("Energodim", "GreenDIM", "5-7-9%", UNDP, EIB) are systematized for three categories of consumers: homeowners, OSBB (condominium associations), and SMEs. The aim of the study is to increase the efficiency of investment decision-making by automating calculations of economic indicators. An extended mathematical model is proposed, which parameterizes the grant co-financing share, energy tariff growth rate, and discount rate for the simultaneous calculation of five key indicators: Payback Period ( ), Discounted Payback Period ( ), Net Present Value ( ), Internal Rate of Return ( ), and Profitability Index ( ). The design of a three-level C4 architecture, a relational ER data model with seven entities, and a declarative Prisma schema are described. Features of the full-stack implementation based on TypeScript, Next.js 14, NestJS 10, PostgreSQL, and the Recharts library are presented. Results of multi-level testing (38 tests, 87% code coverage) and calculation examples confirming a 1.7-fold reduction in payback period for OSBB with a 70% grant are provided. Limitations of the system and prospects for further development are identified, including integration with Open Banking APIs and the implementation of an LLM-based AI module.