PV is an important element of the energy transformation of the residential construction sector. This paper presents a comparison of the actual performance of two PV micro-installations (up to 10 kWp) located on neighbouring single-family buildings with a different orientation: south (roof tilt angle 42°) and east-west (30°). The buildings are located in a cold climate area, in north-eastern Poland. The analysis was based on actual measurements of electricity production and electricity costs incurred according to invoices for the period 2022–2024. Despite the same climatic conditions and lack of shading, the south-facing PV installation achieved 16% higher electricity production per 1 kWp than the one facing east-west. This PV installation also provides 27% higher monthly savings per 1 kWp, resulting from the installation of the PV. In both cases, the installation of the PV system contributed to a drastic reduction in electricity costs at the level of 93–94%. The SPBT for the PV installation with the south orientation is lower that east-west system: 6.3 versus 7.6 years. In order to ensure energy self-sufficiency of the buildings in both cases it is necessary to use electricity storage facilities.