Indicative investment: about €8,000 (5 kWp) to €12,600 (10 kWp)
Expected output: around 1,038 kWh per year per kWp installed
Payback: typically 8-12 years
Self-consumption is what matters
The economics of a solar array today stand or fall on how much of the generated electricity you consume yourself, at the moment of generation. Electricity you use directly saves you the full retail price, whereas electricity exported to the grid is worth considerably less. For a household without particular loads, self-consumption is typically around 30 %. That share is raised significantly by a heat pump, an electric vehicle, a thermal store, or simply shifting washing and drying cycles to the middle of the day.
Roof and siting
A south-facing orientation at a 30-35° pitch is optimal, but south-east and south-west roofs give results only a few percent lower while spreading generation more evenly across the day. Before investing, check for shading from neighbouring buildings and trees - even partial shading of a single panel can disproportionately reduce the output of an entire string. The structural capacity of the roof and the condition of the covering should also be checked: if the roof is near the end of its life, renew it before mounting panels.
Grid connection
Connection requires the consent of the electricity distribution operator. The procedure varies between distribution areas and usually takes several months, so start it early. The terms on which exported electricity is settled change over time in Slovenia, so verify the current arrangement with your supplier before signing a contract.