BangBits

My wife got a luxury greenhouse this spring and while I certainly enjoy the crops coming out of it, it's not exactly aligned with my own geeky hobbies. While unfortunately it's not in the cards for me to invest in a solar system generating green electricity for my entire household, I *can* at least construct a system for a 14m2 greenhouse. The goal is to build an off-grid system for lighting the greenhouse at night using energy provided by the sun in the day, as cheaply as possible. Sourcing components There are many small solar system packages complete with panel, charger and battery; but the price typically starts up around US$200 and that's without the light. For me, part of the fun in something like this, is doing it yourself with cheap COTS components. After some browsing around, ordering and waiting for things to arrive, I ended up with the following: 2x 5W amorph solar panels from local hardware store (US$45). No-name Chinese 10A MPPT charge controller ...

My utility company provides me with ways to see historic consumption of electricity up to a few days ago. However, by that time I have long forgotten when, what and why I did to consume as I did. In order to save power and money on the utility bill, one needs to have some way of monitoring and discovering usage patterns *immediately* as they take place! When I saw you could buy cheap US$50 used industrial strength electricity meters in the form of the Kamstrup 685-382, I decided to buy a few of those. The idea was to have it installed as a secondary meter in my house and try to hook up some sort of communication interface, connected to a low power computer responsible for data acquisition, analysis and presentation. It has to be said up front, that I am far from the only one looking into this. On a Danish engineering discussion forum , I came by other people experimenting with the Kamstrup 382, except that none of the info I came by there seemed to apply to my version of the meter. ...