In solar battery charger systems, the battery requires less power when nearing the end of charge, but the solar panels (or turbines) can still deliver useful power. This could be exploited for heating, cooling, pumping, lighting etc. However, most potential power consumers draw a fixed power, often more than is available, so a system will cycle or tend to draw power from the battery, depending on how it is configured. For resistive loaded (eg heating elements and led lights) a "dimming" function could be implemented to match the excess power to the load. The dimming PWM output is already available in streetlight mode.
What I am proposing is a software addition that comes into play when the battery reaches float charge. It would implement a control loop to adjust the PWM output so as to maintain the float voltage while maximising the power into the load. The SmartSolar MPPT chargers already have all the input data required to generate the control signal.
The PWM signal could drive a standard dimmer, but might also a Victron new product opportunity. For example, I have a need to direct surplus energy to an 800W 240Vac heating element in a camper-van.