This contribution documents the development and validation of open source, model-based control applications for IEC 61499 compliant programmable logic controllers (PLCs) intended for the employment in solar energy systems, such as photovoltaic (PV) systems with a battery and/or heat pump (see Fig. 1). Communication interfaces were created between the simulation tools Polysun and Matlab and the PLC's runtime environment, 4diac RTE (FORTE). This allowed for the development and pre-validation of IEC 61499 control applications in co-simulations with established simulation models. The applications implement the PVprog algorithm, which uses locally sourced PV and load forecasts for charging optimized battery operation (Bergner, et al. 2016), combined with an optional PV curtailment and demand-side management (DSM) of SG Ready heat pumps. For validation, a control application was deployed to a Raspberry Pi 2 and employed in a field test.