A system for monitoring and maintaining a power distribution network of optically switchable windows of a site, the system comprising: a control panel monitor (649, 652, 660) configured to cause: determining a control panel voltage and current at a terminal of a control panel (302, 322, 641, 651); sense circuitry configured to cause: determining a first window controller voltage and current for a first window controller of a plurality of window controllers (309, 329, 409, 655); and one or more controllers configured to cause: generating voltage network data based on a combination of the control panel voltage and current and the first window controller voltage and current, determining an error condition in the power distribution network based on the voltage network data; the system characterised in that the one or more controllers are further configured to cause: determining a corrective action to address the error condition, wherein: (a) the corrective action comprises decreasing a first voltage provided to the first window controller (309, 329, 409, 655) and increasing an amount of time during which the first voltage is provided to the first window controller; (b) the corrective action comprises increasing a first window controller power for the first window controller (309, 329, 409, 655) while decreasing a second window controller power for a second window controller in association with causing a first switchable optical window coupled with the first window controller to have a first tint state; and/or (c) the corrective action comprises increasing the second window controller power in association with causing a second switchable optical window coupled with the second window controller (309, 329, 409, 655) to have a second tint state. a control panel monitor (649, 652, 660) configured to cause: determining a control panel voltage and current at a terminal of a control panel (302, 322, 641, 651); sense circuitry configured to cause: determining a first window controller voltage and current for a first window controller of a plurality of window controllers (309, 329, 409, 655); and one or more controllers configured to cause: generating voltage network data based on a combination of the control panel voltage and current and the first window controller voltage and current, determining an error condition in the power distribution network based on the voltage network data; the system characterised in that the one or more controllers are further configured to cause: determining a corrective action to address the error condition, wherein: (a) the corrective action comprises decreasing a first voltage provided to the first window controller (309, 329, 409, 655) and increasing an amount of time during which the first voltage is provided to the first window controller; (b) the corrective action comprises increasing a first window controller power for the first window controller (309, 329, 409, 655) while decreasing a second window controller power for a second window controller in association with causing a first switchable optical window coupled with the first window controller to have a first tint state; and/or (c) the corrective action comprises increasing the second window controller power in association with causing a second switchable optical window coupled with the second window controller (309, 329, 409, 655) to have a second tint state. generating voltage network data based on a combination of the control panel voltage and current and the first window controller voltage and current, determining an error condition in the power distribution network based on the voltage network data; the system characterised in that the one or more controllers are further configured to cause: determining a corrective action to address the error condition, wherein: (a) the corrective action comprises decreasing a first voltage provided to the first window controller (309, 329, 409, 655) and increasing an amount of time during which the first voltage is provided to the first window controller; (b) the corrective action comprises increasing a first window controller power for the first window controller (309, 329, 409, 655) while decreasing a second window controller power for a second window controller in association with causing a first switchable optical window coupled with the first window controller to have a first tint state; and/or (c) the corrective action comprises increasing the second window controller power in association with causing a second switchable optical window coupled with the second window controller (309, 329, 409, 655) to have a second tint state. (a) the corrective action comprises decreasing a first voltage provided to the first window controller (309, 329, 409, 655) and increasing an amount of time during which the first voltage is provided to the first window controller; (b) the corrective action comprises increasing a first window controller power for the first window controller (309, 329, 409, 655) while decreasing a second window controller power for a second window controller in association with causing a first switchable optical window coupled with the first window controller to have a first tint state; and/or (c) the corrective action comprises increasing the second window controller power in association with causing a second switchable optical window coupled with the second window controller (309, 329, 409, 655) to have a second tint state.