I went with a IotaWatt for measuring my home energy usage. It is based on the ESP8266 and is completely opensource hardware and software. You retain control of your data or you send to an external server.
A toy, in other words. It might be good enough to get a rough idea what eats more or less and when, but it'll never match the utility power meter which is what you're paying by.
cdrc: I rewire my houses myself, because those licensed loons can't be trusted with a 12V light bulb. At least that way _I_ am sure it won't blow up or burn or whatever.
Still, inductive current measurement with the sizes of the clamps they show and typical currents they're measuring isn't accurate at all. Not even considering that voltage measuremens via a wall wart would depend on what load is currently sharing the same wiring.
This might be my bias since I design similar stuff for solar offgrid, where a percent or ten off are that much in capex divided by battery lifetime, then multiplied by battery cost. It bites.
I don't trust inductive clamps at low currents. I would never trust measuring voltage on the same line as a load.
Hall sensors or current shunts; voltage dividers - all driving MCU ADC channels via optoisolated opamps. Everything measured as near to the source as possible. Otherwise you're getting nearly worthless data.
That's actually not correct. Clamps / current transformers are totally fine.