TJ, I think that is a really cool system. When we were considering renting out out granny flat, I found out about putting in a prepaid meter there, but shucks, it would have be really expensive (new cables, municipality, bla-de-bla). Your solution would be perfect.

I think it is a really useful service to offer to landlords who don't want to go through the schlep of installing a whole new cable for a granny flat. I'm not sure how difficult it is to have a prepaid meter installed into a house and connected to the municipality's system, so there may even be scope for landlord's renting out whole houses?

Do you have a website?