Absorption Fridge Running on Solar/Battery/Inverter System

A little correction to your understanding. There is no solar power going to waste. You have excess capacity, so the potential to produce power is going unused. Power is not produced until there is a load to use it. So, I suppose in one sense you either have a wasted opportunity, or an overbuilt system for your needs. Since you already have the system, finding ways to use the capacity is good, however you have to weigh the costs of having that system vs the cost of a couple of tanks of propane.