I'm very interested in this. I spent awhile a year or so ago researching and speccing out a similar project. I was thinking potentially you could offer a product like this for free or very cheap in a deal where the home owner pays their normal current utility rates but you switch them to time of use rates and offload enough of their usage during peak to make a profit. I was also thinking potentially utilities would pay to use devices like these for demand response if you were able to get decent scale which could also be part of the model to offering them for free/cheap.

Some random thoughts:

- I really like the industrial design on your device. The form factor for right above the fridge is exactly what I was envisioning.

- I would love a lower than 20 ms switching time. This is right on the border of might keep your machine on or not. I don't understand why battery backups for hardware have been so stuck and mediocre for so long. Last i checked there was only really one company selling LiFePO for this target. A Pila mini 200-300 Wh with a faster switching time would be amazing and would sell a lot i think if under $300.

- I was hopeful when I first saw this that you had sorted out some way to easily have this run on mains or at least a single circuit. Which i understand would require some level of electrical work but i don't understand why that has to be such a big barrier and why it can't be simplified and standardized enough to the same level as like installing a smart thermostat so even if you are renting it is just a minor inconvenience/cost thing.

- There are significant diminishing returns to the amount of battery backup in my opinion. There is a huge advantage to having any system at all even just a few hundred Wh just to run some lights and charge devices or fridge for a bit. I don't have the data but anecdotally most outages are in the hours range not days range. Still for some reason a HUGE percent of people have absolutely no battery backup at all. And then on the other end full sized power your whole home with no lifestyle adjustments for days systems that costs tens of thousands are equally ridiculous. The sweet spot is a couple kWh in terms of giving you still a lot of flexibility but reasonable prices, oddly to me this seems the most underserved segment.

On my original idea I was thinking of a device similar to your form factor but target squarely at running fridges for ~8-12 hours. Fridge alone won't work for time of use but if you could manufacture this as cheap as possible and make a deal with utilities from the demand response angle and some sort of special time of use deal I think there could be a sweet business. You would have to target specific utilities/regions at a time but if you could get 50k plus units in a region and at under $200 to the consumer I think utilities would be interested.