Reverse Active Energy (kWh Electrical Meter)

This would be most common when speaking of a co-generator setup when power generation is intermittent...A meter can be used to tweak output during peak usage hours and reversed during off-peak hours to maximize output monetarily...

http://www.szstar.com/en/product/product_97.aspx

I may be a bit late here.

Reverse energy is a common fact, if there is a generator producing some output power there is a current that may be in phase with the Vac being generated - if another power source is place in parallel and synchronized with the first generator the current in this case will flow toward the fist if the voltage is at a higher level, if there is a load applied to the Vac the load will start receiving energy from both power sources if both are synchronized and in PHASE to each other, if the second power source has a higher Vac voltage then this unit will be supplying the power that the load attached to the circuit is receiving and the first generator is there idling and not supplying power to the load -- This is the basic arrangement used by the power plants to synchronize and to share power when needed .