Building-integrated photovoltaics (PVs) is one of the most promising and elegant ways of producing on-site electricity. The compact and cost-effective PV integration system needs to be developed to convert dc voltage into ac compatible with the grid. A single-stage PV inverter is proposed, and its design and control system implementation are focused on. The proposed system is able to transfer active power to the grid with maximum power point tracking. At the same time, the PV inverter can control reactive power and suppress harmonics due to non-linear loads. By coupling to grid via a series LC branch, the proposed system operates on a dc bus voltage much lower than that of the conventional PV inverter, so that less PV panels need to be connected in series. Therefore, the proposed system is a low-cost and multi-functional alternative to PV inverters in building-integrated applications. Simulation and experimental results are provided to validate its effectiveness.