Richard Stovall's (SolPowerPeople CEO, Instructor) review of the new 2014 rules for interconnection of solar PV systems.

1. 705.12(D) Point of Connection
Utility Interactive Inverters
By
Richard Stovall, CEO SolPowerPeople
#SolarMOOC Webinar 12/19/13
12PM CST

2. 705.12(D)(1)
This change is meant to accommodate
microinverters and AC module systems where
there may be more than one inverter feeding
one OCPD.

3. 705.12(D)(2)
(1)Feeders
(2)Taps
(3)Busbars

4. 705.12(D)(2)(1)

5. 2014: Utility Interactive Inverters
Feeder Conductor Ampere Rating
705.12(D)(2)(1)(a)
225A
100A
200A
400A
.
..
.
..
..
PV – 160A
Continuous
.
.
200A
MLO
200A
200A
200A
200A + (160A x 1.25) =
400A
600kcmil
225A
30A
50A
200A
1000A Bus
200A, 3/0 AWG rated at
200A at 75ºC, Table
310.15(B)(16)
50A
.
.
..
..
50A
50A
400A Bus
The feeder conductor on the load side of the inverter AC output connection
must have an ampacity not less than the feeder overcurrent protective device,
plus 125% of the inverter output AC circuit rating.

6. Table 310.15(B)(16)

7. Table 310.15(B)(16)

8. PV – 160A
Continuous
100A
225A
200A
1000A Bus
200A
200A
200A
225A
200A
200A
200A
400A
.
..
.
..
.. .
.
.. .
2014: Utility Interactive Inverters
Feeder Conductor Ampere Rating
705.12(D)(2)(1)(b)
200A, 3/0 AWG
rated at 200A at
75ºC, Table
310.15(B)(16)
200A Bus
The feeder conductor on the load side of the inverter AC output
connection must have overcurrent protection on the load side of the
inverter output AC connection sized not greater than the ampacity of the
feeder.

9. Table 310.15(B)(16)

10. 705.12(D)(2)(2)

11. Feeder – 10 Ft. Tap
705.12(D)(2)(2)
PV – 160A
Continuous
Minimum Feeder Tap
[200A + (160A x 1.25)] x .10 = 40A, but
in no case less than the rating of the
100A OCPD
225A
100A
200A
200A
.
.
. .. .
. .
. .. .
100A
200A
225A
3 AWG rated
100A33 75ºC
at
LOAD
LOAD
30A
20A
200A
1000A Bus
200A
20A
20A
15A
LOAD
LOAD
LOAD
200A
400A
.
..
.
..
..
.
.
.
. .
. .. .
. .. .
30A
50A
50A
50A
50A
LOAD
LOAD
LOADS
100A Bus
400A Bus
Feeder tap between the feeder overcurrent protection device and the
inverter AC output protection device, must have an ampacity not less than
the feeder overcurrent protection device, plus 125% of th e inverter output
AC circuit current rating in accordance with 240.21(B).

12. Table 310.15(B)(16)

13. Taps not over 10ft long
• 240.21(B)(1)

14. Feeder – 25 Ft. Tap
705.12(D)(2)(2)
PV – 160A
Continuous
Minimum Feeder Tap Size
[200A + (160A x 1.25) x .33 = 133A
.
.
200A
225A
100A
.
.
. .. .
. .
. .. .
100A
200A
225A
1/0 AWG rated
33
150A at 75ºC
LOAD
LOAD
30A
20A
200A
1000A Bus
200A
20A
20A
15A
LOAD
LOAD
LOAD
200A
400A
.
..
.
..
..
200A
.
. .
. .. .
. .. .
30A
50A
50A
50A
50A
LOAD
LOAD
LOADS
100A Bus
400A Bus
Feeder tap between the feeder overcurrent protection device and the
inverter AC output protection device, must have an ampacity not less than
the feeder overcurrent protection device, plus 125% of the inverter output AC
circuit current rating in accordance with 240.21(B).

15. Table 310.15(B)(16)

16. Taps not over 25ft long
• 240.21(B)(2)

17. EC&M Article on Feeder Taps
• Written by Mike Holt
• http://ecmweb.com/code-basics/feeder-taps

18. 705.12(D)(2)(3)(a)
AKA 100% RULE

19. 200A MAIN
PV SUPPLY
OCPD
225A BUS

20. 2011 Code is based on the OCPD of the inverter. Therefore the
MAX OCPD fed to this panel in this location is 25A:
225A(busbar rating) minus 200A (main breaker rating) = 25A
200A MAIN
PV 25A
OCPD
225A BUS

21. 2014 Code is based on the 125% of the inverter continuous
output current. Is there a difference? Yes. There may be more
design flexibility with the new rule.
200A MAIN
PV SUPPLY
OCPD
PV SUPPLY
OCPD
225A BUS

22. Example: 2 branch microinverter circuits. With 25A max
(inverter continuous output x 125%) Assuming M215 (215Wac)
that’s 22 inverters: (25A/(215/240*1.25)=22.32
200A MAIN
PV SUPPLY
OCPD
PV SUPPLY
OCPD
225A BUS

23. Example: 22 microinverters with allowable 20A OCPD per circuit
(11 each). In 2011 Code this is not allowable because it violates
the 25A max OCPD requirement.
200A MAIN
PV 20A
OCPD
PV 20A
OCPD
225A BUS

24. 705.12(D)(2)(3)(b)
AKA 120% RULE

25. 200A MAIN
PV SUPPLY
OCPD
225A BUS

26. 2011 Code is based on the OCPD of the inverter. Therefore the
MAX OCPD fed to this panel in this location is 70A:
1.2 X 225A(busbar rating) minus 200A (main breaker rating) = 70A
200A MAIN
PV 70A
OCPD
225A BUS

27. 2014 Code is based on the 125% of the inverter continuous
output current. Is there a difference? Yes. There may be more
design flexibility with the new rule.
200A MAIN
PV SUPPLY
OCPD
225A BUS

28. Example: 4 branch microinverter circuits. With 70A max
(inverter continuous output x 125%) Assuming M215 (215Wac)
that’s 62 inverters: (70A/(215/240*1.25)=62.51
200A MAIN
PV 20A
OCPD
PV 20A
OCPD
PV 20A
OCPD
PV 20A
OCPD
225A BUS
TOTAL: 80A PV OCPD, OKAY IN 2014 CODE

29. Example: 62 microinverters with 20A OCPD per circuit (15 X 2
and 16 x 2). In 2011 Code this is not allowable because it
violates the 70A max OCPD requirement.
200A MAIN
PV 20A
OCPD
PV 20A
OCPD
PV 20A
OCPD
PV 20A
OCPD
225A BUS

30. 705.12(D)(2)(3)(c)

31. 200A MAIN
20A 2-POLE
PV OCPD
25A 2-POLE
EMPTY
20A 2-POLE
PV OCPD
15A 1-POLE
60A 2-POLE
30A 1-POLE
20A 2-POLE
PV OCPD
50A 2-POLE
225A BUS

32. LINE A
LINE B
25
25
20
20
20
20
20
20
50
50
60
60
30
15
225
210
200A MAIN
20A 2-POLE
PV OCPD
25A 2-POLE
EMPTY
20A 2-POLE
PV OCPD
15A 1-POLE
60A 2-POLE
30A 1-POLE
20A 2-POLE
PV OCPD
50A 2-POLE
225A BUS

33. 705.12(D)(2)(3)(d)

36. 705.12(D)(3)

37. 705.12(D)(4)

38. NOT SUITABLE FOR BACKFEED
LOAD
LINE

39. 705.12(D)(5)

40. 705.12(D)(6)

41. THANK YOU!!
•
•
•
•
•
Richard Stovall
CEO SolPowerPeople
rstovall@solpowerpeople.com
512-825-3051
www.solpowerpeople.com