A battery-free device is provided with one or more series or parallel capacitive networks. One or more solar panels are used to charge the capacitive networks and one or more charging circuits are used to control the charging of the capacitive networks. One or more DC-DC converters maybe used to provide a voltage to the device, a remote monitoring or controlling function, and, optionally, a user interface. In those instances when it is desired that the monitoring or controlling function remain powered at all times, the control circuitry is preferentially preserved at the expense of the other features of the device such that if, for any reason, the capacitive network is drained after running the other features, there will still be sufficient power stored in capacitive network to maintain the monitoring or controlling function.