Precise/low-cost active, apparent and reactive energy calibration

Here is a complete and fully operational open source application to upstream energy data from the Olimex Energy Shield (based on ADE7753) to Pachube using the Nanode 5 board, or equivalent Arduino with ENC28J60 ethernet IC.

Unfortunately I had to disable the apparent and reactive channels at this stage as I have not found a precise and economical way of performing the calibration. Dedicated energy meter calibration instruments such as Fluke are hugely expensive.

Any suggestion to achieve precise and low-cost active, apparent and reactive energy calibration?

Kind regards - Thierry

PS: refer to the "Pachube/Nanode/ADE7753 - Energy Metering to Pachube" discussion for more details on this project.