Energy harvesters are an evolving technology for the Internet of Things and for all areas in which devices and sensors are operated with low power consumption. In general, they utilize energy sources from the environment to harvest electrical energy. One way of doing this is via the piezoelectric effect, which enables the utilization of ambient vibrations. Besides piezoelectricity, it is also possible to harvest electrical energy from temporal thermal fluctuations, which is known as pyroelectricity. Since ambient vibrations and thermal fluctuations are often present in the same devices, it is logical to utilize both effects to increase the amount of energy harvested. The combination of utilizing piezo- and pyroelectricity is called pyropiezoelectricity. Even when combining both effects, the energy harvested is usually too low to continuously power devices. Therefore, the harvesting structure must be connected to an electrical circuit that rectifies, accumulates and stores the electrical signal from the base structure. The simulation of such a pyropiezoelectric harvesting structure together with the attached electrical circuit is the main topic of the presentation. While the base structure is modeled via linear thermopiezoelectricity [1], the connected circuit is taken into account by suitable boundary conditions. All three fields (mechanical, electrical and thermal) are fully coupled and solved simultaneously so that all coupling phenomena can be taken into account. In [2], this method was already used to compare experimental results for a cantilever beam with simulation results for a simplified model with an attached single resistor. The extension of the simulation framework to be able to simulate more complex structures is part of the presentation.