A processor and power broker for controlling the obtaining, distribution and usage of electrical power for electronic devices such as peripherals of thermostats. Sources of power may incorporate batteries, energy harvesting modules, energy storage capacitors, and power lines. The power broker may maintain charge on the capacitors, operate the energy harvesting modules, control usage of the batteries, and utilize power line sources when available. Loads such as the peripherals may need to request approval for energy usage. Energy usage and conservation may be managed by the power broker according to a power scheme. A power scheme may consist of a set of rules as to how energy usage by the peripherals is to be managed. The rules may also indicate as to how the energy sources are managed.