This paper develops a framework for buildings-to-distribution network (BtDN) integration. BtDN couples buildings, photovoltaic (PV) generation, and battery energy storage systems (BESS) to the power distribution network, using model predictive control to solve a joint optimization problem which minimizes building energy use while implementing reactive power control of PV and BESS inverters to maintain nodal voltage within prescribed limits at all times. The framework is tested in a pilot simulation study and improves upon a naïve control algorithm, showing 24% reduction in building energy usage, 40% reduction in network losses, and a complete elimination of voltage deviation.