Various embodiments herein relate to power distribution networks for optically switchable windows. A number of different topologies are provided. In many embodiments, a control panel may be connected with a trunk line, which is connected to a plurality of optically switchable windows. The plurality of optically switchable windows may be powered by the shared trunk line. This topology provides substantial improvements over topologies in which each optically switchable window is connected to the control panel via separate, individual lines. Further, certain embodiments herein relate to installation kits for installing power distribution networks for optically switchable windows.