Method to Measure Wholesale Stored Energy

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Eugene Andrews
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1 Method to Measure Wholesale Stored Energy Andrew Levitt Senior Market Strategist, Emerging Markets Jan 31 DER Subcommittee

2 Intro to Pigtail Some generators connect directly to adjacent or on-site loads, esp. for emergency backup. Generator could be same owner as adjacent load, in which case self supply. Or Generator could be LSE whose sale through the pigtail is regulated by the state. Or Generator could fall under a state rule that exempts such direct sales from regulation (e.g., On Site Generator rules. With storage: what s the method to measure wholesale stored energy vs. retail stored energy? SOLR STOR Utility grid PIGTAIL LOAD

3 Definition For current discussion, Wholesale Stored Energy is energy that is both: 1. Withdrawn from the grid.. Later released to the grid as part of a wholesale transaction. 3

4 Use Case: Storage Alone

5 Utility grid Definitions POI LOAD STOR PIGTAIL 5

6 Definitions MWh Battery discharge to grid Battery charge from grid Net POI 50 MWh 6

7 Definitions MWh Battery discharge to grid Battery charge from grid Net POI 50 MWh 7

8 40MWh of Energy That s Not Wholesale Stored Energy MWh Battery discharge to grid Battery charge from grid Net POI MWh 8

9 Method To Determine Wholesale Stored Energy General principle: Energy that the battery takes off the grid and later returns to the grid is Wholesale Stored Energy. The remaining energy is Not Wholesale Stored Energy and should be accounted for accordingly. Monthly net of (battery charge from grid) and (battery discharge to grid) = Not Wholesale Stored Energy = (battery station power withdrawals + other). The remaining withdrawals are Wholesale Stored Energy MWh Battery charge from grid Battery discharge to grid Net POI MWh 9

10 Meters and Method Details: Storage alone Monthly net of MWh: (battery charge from grid) - (battery discharge to grid) = (battery station power withdrawals + other). Battery charge from grid = integrated POI value when POI withdraws Battery discharge to grid = integrated POI value when POI injects Possible measure of battery station power = monthly integral of POI meter MWh MWh Battery charge from grid Battery discharge to grid Net POI STOR M POI Meter Utility grid PIGTAIL LOAD Other + Battery Station Power is net monthly negative energy position after all injections are netted against withdrawals.

11 Use Case: Storage + Generator

12 Utility grid Definitions Net POI SOLR LOAD STOR PIGTAIL 1

13 Example 1: Solar to grid :00 6:00 1:00 18:00 Solar to grid Battery charge from solar Battery discharge to grid Battery charge from grid Net POI 13

14 Example : Battery Charge from Grid and Battery Discharge to Grid :00 6:00 1:00 18:00 Solar to grid Battery charge from solar Battery discharge to grid Battery charge from grid Net POI 14

15 Example 3: Battery charge from solar :00 6:00 1:00 18:00 Solar to grid Battery charge from solar Battery discharge to grid Battery charge from grid Net POI 15

16 Example 4: Battery charging from solar & grid at the same time :00 6:00 1:00 18:00 Solar to grid Battery charge from solar Battery discharge to grid Battery charge from grid Net POI 16

17 Example 5: RegA + Solar :00 6:00 1:00 18:00 Solar to grid Battery charge from solar Battery discharge to grid Battery charge from grid Net POI 17

18 Example 6: RegD + Solar :00 6:00 1:00 18:00 Solar to grid Battery charge from solar Battery discharge to grid Battery charge from grid Net POI 18

19 Method To Determine Wholesale Stored Energy General principle: Energy that the battery takes off the grid and later returns to the grid is Wholesale Stored Energy. The remaining energy is Not Wholesale Stored Energy and should be accounted for accordingly. Monthly net of (battery charge from grid) and (battery discharge to grid) = Not Wholesale Stored Energy = (battery station power withdrawals + other). The remaining withdrawals are Wholesale Stored Energy Battery charge from grid Battery discharge to grid Battery charge from solar Solar to grid Net POI 19

20 Meters and Method Details: Storage + Generation At Same Site Monthly net of MWh: (battery charge from grid) - (battery discharge to grid) = (battery station power withdrawals + other). Battery charge from grid = integrated POI value when POI withdraws Battery discharge to grid = integrated battery submetered value when battery discharging and POI injects Possible measure of battery station power = monthly integral of POI meter 1 POI Meter M Utility grid SOLAR LOAD Battery charge from grid Battery charge from solar Net POI Battery discharge to grid Solar to grid STOR Battery submeter SM PIGTAIL 0

Grid Integrated Resources. Update to Energy/Ancillary Services. DERS March 2, 2018

Grid Integrated Resources. Update to Energy/Ancillary Services. DERS March 2, 2018 Grid Integrated Resources Update to Energy/Ancillary Services DERS March 2, 2018 1 Energy Accounting At stakeholder request, the next three slides present EDC/LSE energy accounting under the GIR proposal.