Profitability of Investment in Photovoltaic Panels with Energy Storage for Households: A Case Study

Abstract

Theoretical background: Poland, committed to an energy transition and to increasing the share of renewable energy sources (RES), has experienced dynamic growth in photovoltaics (PV), particularly within the sector of prosumer micro-installations. This development is driven by declining technology costs, rising energy prices, increased consumer awareness, and supportive government programs. Self-consumption has become a critical factor in determining investment profitability, especially under the net-billing system. There is growing interest in energy storage solutions, whose falling prices have made it possible to further increase self-consumption. The profitability of individual investments depends on installation costs, electricity prices, and the applicable settlement system.

Purpose of the article: The aim of this article is to conduct an economic analysis of the profitability of a prosumer photovoltaic installation combined with an energy storage system. The study focuses on current conditions in Poland, including the net-billing system and available support programs (e.g., “Mój Prąd”). The objective is to provide a detailed evaluation of costs, benefits, and profitability indicators (Payback Period, Discounted Payback Period, Net Present Value, and Internal Rate of Return). The analysis is based on a case study, with the goal of delivering a reliable economic assessment for potential individual investors.

Research methods: The study was conducted as a case study of a two-story residential house in Kraków (approx. 220 m²), heated electrically with a heat pump. In 2023, a 9.96 kWp PV installation and a 9.2 kWh energy storage unit were installed. The investment was financed with own funds, with a grant covering 50% of the capital expenditures. The household operates under the net-billing system. The profitability analysis uses actual production and consumption data from 2024, assuming the start of system operation in 2025. Savings were calculated as the difference in energy costs with and without PV, plus 30% of the value of electricity fed into the grid at wholesale prices. The assessment of profitability employed the discounted payback period method, Net Present Value (NPV), and Internal Rate of Return (IRR).

Main findings: The analysis demonstrated that the investment in a PV system with energy storage is economically viable for the examined case. The discounted payback period is approx. seven years. The NPV is positive, amounting to PLN 49,580, while the IRR stands at 13%, significantly exceeding the assumed opportunity cost of capital. The investment generates profits after the payback period. The study suggests that such a solution is particularly advantageous for households with higher electricity consumption, such as those using heat pumps. The results are subject to uncertainty regarding future electricity prices and regulatory changes, highlighting the need for ongoing analysis.