Nicholas Hall, the starter of the SUNBOX project, wants to discuss fault tolerance design with you.
In an embedded system, the voltage being supplied to the integrated circuit may be measured and used as feedback for an embedded program.
Behavior of this program may be driven according to rules that do not depend on state, allowing an integrated circuit to be designed that can have rapid fluctuations in power but still sequentially execute a program.
Please observe this lowpass filter circuit.
If execution of the program is stateless, your only state is your program counter. The absolute worst case, even if you had no capacitative ability in your circuit, is that you lose your position in your program. Using a very simple capacitative design, a program may be designed that ensures it will not run unless it has sufficient capacitance to save the program counter.
This allows a circuit to be designed that is fault tolerant enough to run low-powered programs using only a very large capacitor and somewhat faulty and unreliable electrical generator.
This design can be generalized to suit almost any application with a desired predefined halting condition that does not depend on state or can shut down cleanly without power.