When I bought the solenoid for my latch I speced a continuous duty type, not really knowing why but the price was the same as intermittent duty. I never used it with storms approaching etc. but there is nothing I can do to protect myself against some idiot taking out a power pole or a substation fire. When I figured out to set the mechanics up to default to unlatch I experimented with power always on to said solenoid. It got entirely to warm for my satisfaction. Also, sometimes the solenoid will buzz when powered and I intended to attach it to a wall. (Can you say soundboard?)
Battery power is ok but the solenoids available are 12 volt and above. I did toy with the idea of using a motorcycle battery as it is small easily recharged and can deliver the necessary amps. I think I rejected this idea because of the addition of the battery and charger. And, just when will the battery power run out? Before the capacity of the diaper? Will you be late for work?
Anondl
PS As for saleability, diaperboyMKE is right, you couldn't buy enough liability insurance.