1. Case Study on Distributed Generation Rate Options: From Both Sides of the Meter
Presented by
Douglas Danley at
36th UASEE/IEEE North America Conference
24 September 2018 Washington, DC

2. My Goal Today
Evaluate various residential rate structures using a year’s worth of real data from a residential PV system in Maryland.

3. My Goal Today
Evaluate various residential rate structures using a year’s worth of real data from a residential PV system in Maryland.
Each rate is analyzed from both the customer perspective (i.e., total bill)

4. My Goal Today
Evaluate various residential rate structures using a year’s worth of real data from a residential PV system in Maryland.
Each rate is analyzed from both the customer perspective (i.e., total bill) and the utility perspective (i.e., distribution revenues)

5. Solar Rate Structures in the News

6. Cost of Solar Energy

7. Cost of Solar Energy
365 Wp x $0.41/Wp
$149.65

8. Cost of Solar Energy $149.65 ÷ 13,028 kWh =
Location: Baltimore, MD
Single Axis Tracking
25 Year Life
0.8% annual degradation
365 Wp x $0.41/Wp kWh x 25 yrs x 0.9
$ ÷ 13,028 kWh =

9. Cost of Solar Energy Unit Energy Cost $149.65 ÷ 13,028 kWh = 1.1 ¢/kWh
Location: Baltimore, MD
Single Axis Tracking
25 Year Life
0.8% annual degradation
Unit Energy Cost
365 Wp x $0.41/Wp kWh x 25 yrs x 0.9
$ ÷ 13,028 kWh = 1.1 ¢/kWh

10. 1.1 ¢/kWh

11. Standard Metering
Retail
One Meter. Power flows in one direction – from grid to house.

12. Avoided Cost / FIT / Value of Solar
Production Metering
Retail
Avoided Cost / FIT / Value of Solar
Two Meters
Power flows in two directions – from PV to grid and from grid to house. Metered at separate rates.

13. Net Energy Metering
Retail
One Meter. Power flows in both directions between grid and house. Production is credited at retail rate.

14. Excess Energy Metering
Retail
Avoided Cost / FIT /
Value of Solar
One Meter.
Power flows in both directions between grid and house, but there are separate rates for consumption and production.

15. Zero Export Metering One Meter.
Retail
No export!
One Meter.
Power flows in one direction between grid and house. Home automation senses excess and uses within the house to prevent export.

16. My Residential PV System
Location: Germantown, MD
Array: 6.89 kWp
Inverter: SolarEdge
Net Metered usage 3,673 kWh
PV generation 7,347 kWh, of which 3,686 kWh was exported to the grid.
Net energy usage 11,020 kWh
PV contribution 67% of annual household load

17. Rate Structures To Be Analyzed
Baseline Bill (no solar)
Retail Net Metering
Distributed Energy Buyback / Value of Solar
Adjusting the Fixed Cost of Service
Demand Charges
Time-of-Use Rates
Distribution System Charges

23. Conclusions
Increased fixed charges when combined with lower energy charges will disincentivize energy efficiency as well as distributed generation
Demand rates and TOU rates will be targets for increasingly advanced home automation combined with residential energy storage
“DG surcharges” are likely to be viewed as anti- environmental as well as antagonistic towards customers who choose to install solar
Solar costs are still falling and adoption will increase, continuing to change the economics
Ratemaking is an difficult challenge and utilities need to look “more than one move ahead”

25. Doug Danley doug.danley@gmail.com