If you are producing more than you are consuming, then the excess energy goes to the grid. Conversely, if you are consuming more than you are producing, then all of your generated energy is being consumed by you, and any additional energy requirements you have will be provided from the grid (i.e., in-flow kWh). The figures below illustrate two basic scenarios for power flow between the DRG, customer's facility, and the grid.
Why is the generated energy shown on my customer-owned meter different from the Oncor meter out-flow kWh energy register?
Customer-owned metering is installed to measure the total energy generated by the renewable system. Customer generation can serve customer loads or be exported to the grid. The Oncor out-flow kWh register only measures the energy sent to the grid. In the example below you can see that customer generation totaled 1,000 kWh, but only 500 kWh went through the Oncor out-flow (057) register to the grid.
The only time you would expect to have your Customer Owned Meter total generation monthly output be equal with the Oncor out-flow kWh register would be when you have no energy being consumed at your facility. Oncor encourages customers to take monthly meter readings of their customer owned meter at or close to the Oncor end of cycle meter reading dates. Knowing both the amount generated by your renewable system and the amount sent to the grid (out-flow 057) will enable you to estimate how much customer owned generation you used directly from your generating system.
In the example below, the customer consumed 1,500 kWh but only registered 1,000 kWh on his in-flow (001) register. The customer consumed 500 kWh directly from his generating system and returned 500 kWh to the grid.
For additional information, refer to: How do I read my distributed renewable generation (DRG) meter?
Net Metering at Oncor
Oncor utilizes metering that measures in-flow and out-flow energy in separate channels.
"Net metering" is commonly defined as a single channel meter (some say "spins forward and backward" if an analog meter) that allows for off-sets (some say energy banking) and results in one value being reported at the end of the billing period. TDUs in Texas are not allowed to install meters that subtract out-flow from in-flow within the meter. Anytime you simultaneously generate and consume electric energy you are "netting" and avoiding using energy you would have purchased at retail rates.