The present disclosure describes an energy device with a solar module having a form factor configured to be inserted into and to match an inner portion of a coin-type cell holder of an electronic device. The solar module includes one or more photovoltaic cells to capture energy from ambient light and a pair of electrodes. The energy device may be configured to provide, to the electronic device via contact with the coin-type cell holder, electric energy produced from the ambient light energy. The solar module may include a converter module to convert the ambient light energy into the electric energy. The energy device may also include an energy storage module and/or a power management module that are stackable below the solar module with electrical connectivity to the solar module, and that combined with the solar module have the appropriate form factor for the coin-type cell holder.