The paper focuses on the cost-effective design of a grid-connected rooftop photovoltaic (PV) system in Poland. The work aims to find the optimal system configuration, indicated by the highest Net Present Value (NPV), for the scenario of Net-Metering (NM) and Feed-In-Tariff (FIT) support mechanisms. PVsyst software was used to simulate the performance of various system sizes, tilts of the modules, as well as types and capacities of PV panels and inverters. Financial analysis was performed, by treating PV generation data in an economic evaluation model. At first, it was necessary to determine the building’s electricity demand, using the bottom-up method. Preliminary analysis, based on generic components, allowed to estimate the optimal size range of the system. Detailed simulations were later conducted in the specified ranges. Results of the simulation showed that the system capacity-optimized for NM was nearly twice bigger than for FIT, but the NM support system proves to be more beneficial, as it generates significantly larger NPVs. The sensitivity analysis showed that the three parameters most affecting the NPV of the systems studied were: electricity prices, the building's electricity demand, and capital expenditures.

本文重点研究波兰的并网屋顶光伏（PV）系统的经济高效设计。这项工作旨在找到最佳的系统配置，以最高的净现值（NPV）表示，适用于净计量（NM）和上网电价（FIT）支持机制。PVsyst软件用于模拟各种系统尺寸，模块的倾斜度以及PV面板和逆变器的类型和容量的性能。通过在经济评估模型中处理光伏发电数据来进行财务分析。首先，有必要使用自下而上的方法确定建筑物的电力需求。根据通用组件进行的初步分析可以估算系统的最佳尺寸范围。随后在指定范围内进行了详细的模拟。仿真结果表明，针对NM优化的系统容量几乎是FIT的两倍，但是NM支持系统被证明是更有利的，因为它会产生更大的NPV。敏感性分析表明，影响研究系统净现值的三个参数分别是：电价，建筑物的电力需求和资本支出。