Profitability of Solar Photovoltaic Rooftop Systems in Buildings with Medium Sized Loads

摘要

In Sweden, it is generally most feasible to install solar photovoltaics (PV) primarily for self-consumption, as long as there either is a large enough load when the sun shines or that over-generation is generously compensated. Currently there are two support schemes for PV: a capital subsidy and a tax rebate for grid feed-ins. However, the latter is not available for systems above 100A, thus making self-consumption highly important for these systems. This paper studies the profitability of systems connected to loads from 100 to 700 MWh, most of them above 100A. In particular, it compares multi-family buildings to other building types. Analyses were based on measured electricity use matched to simulated PV yield and current market conditions. Calculations were conducted with and without consideration of existing roofs. In general, the supply points in multi-family buildings had less favorable load profiles than the ones in other buildings, which resulted in lower self-sufficiencies as well as relatively lower profitability and smaller system sizes. The support schemes turned out to be crucial for the profitability in most cases, but not all. For supply points in other building types with loads above 300 MWh profitable systems were found also without a subsidy. Taking areas and orientations of existing roofs into consideration drastically decreased the share of profitable systems.