1. AC COUPLE

2. AC Coupled Systems Growing market segment Can be confusing!
Can be complicated!
Numerous ways to go
MidNite has taken most of the mystique out of the equation

3. One inverter capable of AC coupling The SMA Sunny Island is the most difficult inverter to hook up to pass inspection More on that later

4. OutBack inverters were the first to AC couple, but each inverter is only 120VAC
Grid tie inverters are 240VAC
2 inverters required in this setup

5. It is interesting to note that 90% of this system would be the same for off-grid or battery backed up grid tie.
Can you tell which type this is?

6. 120V Magnums are also not easy to AC couple

7. Yes, you can even screw up a MidNite E-Panel for the XW inverter
Yes, you can even screw up a MidNite E-Panel for the XW inverter. This is functional, but messy

8. Before we show how to make AC coupling easy, let’s see just what AC coupling is

9. Why AC Couple 1. a way to use those expensive grid tie solar panels during a power outage 2. Provides limited power during a power outage 3. Allows the installer to go visit their grid tie customers with something useful to sell

10. What is AC Couple
AC Coupling is a controlled back feed to a battery based inverter
A back feed is hooking up AC to the output of an inverter
Normally when you back feed an inverter, they blow up (try it sometime, smile)
AC coupling is a synchronized back feed
The grid tie inverter shifts frequency to match the battery based inverter before connecting. This makes it ok to do

11. AC Coupling of inverters
Battery-less grid tie inverters require a grid to be connected before they will turn on. The grid must meet certain voltage and frequency parameters.
You have all heard about anti-islanding requirements that the inverters must meet
Battery based sinewave inverters can meet these requirements
Inverters do not need to be grid tie listed

12. AC Coupling of inverters
Not all battery based sinewave inverters are capable of backfeed.
Your choices in North America are:
SMA Sunny Island
Outback FX, VFX and Radian
Magnum PAE series
Schneider XW series

13. SMA Sunny Island

14. AC Coupling of Inverters
The Sunny Island and Sunny Boy communicate with each other to insure proper battery charging during a power outage.
No other inverter combination can claim this

15. SMA Sunny Island Since the Sunny Boy output is 240VAC and the Sunny Island input is 120VAC, a step down autoformer is used

16. SMA Sunny Island Notice that the output of the SB connects to the output of the SI The autoformer changes 240V to 120V

17. SMA Sunny Island The SI inverter has only one AC input
SMA Sunny Island The SI inverter has only one AC input. We provide an optional ATS that5 fits inside our SMA E-Panel

18. The Sunny Island/Sunny/ Boy combination was designed to be AC Coupled They thought of everything (from a European point of view)

19. SMA in Germany still has problems with the US NEC code
SMA in Germany still has problems with the US NEC code. The Sunny Island is not easy to install to meet code

20. SMA had been requesting that MidNite Solar make them an E-Panel for years. We finally did We did not realize how big a deal this was going to be!

21. The pre-wired system shown here is as plug and play as they come The top piece is the autoformer Battery box and cabling is included and drop ships where you want it

22. E-Panel with ATS option installed All SMA E-Panels come wired for 240VAC (2 SI inverters)

23. E-Panel shown with AC bypass switch, 500 amp shunt and sub panels breakers installed

24. Dual systems do not require an autoformer

25. Need a large AXC coupled system?

26. We even designed a 1000 amp battery combiner for this system

27. SMA AC Coupled systems SMA AC Coupled solutions for 1 to 4 inverters
4,500 watts to 24,000 watts
Purchase pre-wired and tested or parts
Remember those tech service people we mentioned? You may need to involve them on your first system.

28. Enphase AC Coupled systems
Enphase systems are pretty much the same as all others
When using a Magnum PAE inverter, you must limit the PV array to less than 4000 watts.
Failure to do this will result in inverter failure
Magnum is the easiest for Enphase AC coupling

29. This exact system is now on our price list and available for order

30. The disco combiner is there for reference only We do have a three string AC disco combiner

31. The Grid Tie inverter shown can be Enphase or any 240VAC grid tie up to 4000 watts of actual output

32. Since the two different inverters have no communication, we install a SSR to knock the grid tie off line as required

33. This is a pictorial wiring diagram

34. Uncontrolled battery charging
Magnum and OutBack inverters charge batteries from AC connected to their outputs
The inverters sense circuits that control charging are on the AC inputs not the output, therefore cannot control charging
These inverters charge wide open and cannot taper off.
A relay is required to disconnect the GT

35. Uncontrolled battery charging
SMA has controlled battery charging and tapers off as the batteries get charged
This requires that the AC coupled system is comprised of a Sunny Island and Sunny Boy. They were designed to work together.
No external relay required

36. Uncontrolled battery charging
Schneider WX shifts frequency to knock the grid tie inverter off line for 5 minutes.
The XW does this with any brand grid tie inverter, but battery charging does not taper off.
No external relay required

37. Uncontrolled battery charging
OutBack inverters do not taper off like the SMA, nor do they shift frequency like the XW
You must add an external relay between the grid tie inverter and the battery based inverter
The OutBack aux output can supply the power & control to drive an external relay

38. Uncontrolled battery charging
Magnum inverters do not taper off like the SMA, nor do they shift frequency like the XW
You must add an external relay between the grid tie inverter and the battery based inverter
The Magnum router can supply the control to drive an external relay, but not the power

39. The solid state relay eliminates battery over charging

40. Hook up the output from your grid tie inverter here

41. Hook up the sub-panel here This is the AC output of the inverter

42. Hook up the mains utility connection here

43. Hook up the neutral and ground connections from the main distribution panel here

44. 4000 watt limit This limit only applies during power outages
We have another method that allows larger arrays, but reduces the array power during outages
This is a radical modification, but works

45. A solid state relay is placed inside the combiner to reduce quantity of strings

46. This is a self contained pre-wired AC coupled system

47. All wiring is behind the breaker panel

48. All required over current and disconnects are in place, wired and tested

49. Multiple battery configurations available. Shown is just one

50. The enclosure for this system is made from aluminum and is suitable for outdoor locations

51. Nice looking AC coupled addition to an existing grid tie system

52. OutBack and Schneider 2 OB inverters are required for AC Coupling.
OB offers superior regulation during outages and has a built in aux circuit
Schneider offers a good inverter for AC coupling. The XW will shift frequency to knock the GT offline

53. Install responsibly, always use protection

54. SPD 600’s installed in Montana

55. The MNBCM is very inexpensive ($69 list) It offers at a glance assurance that the batteries are full. Do not waste your money on a shunt based battery monitor for an AC coupled system. The batteries are always full.

56. Three technical support people
All three will be able to help answer your questions. Ryan, Tom and Kim
Beware, Kim will try to sell you something

57. MADE IN USA

58. The MidNite kitty