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h2009 asked

AC PV and DC PV sync, or am I seeing something else?

Dear All

Let me list my system out first so there’s no confusion.

My system is grid disconnected (relay) between 5:30am and midnight. MP2's are set to deliver 240v rather than 230v. Currently testing out DESS, but even before this same results.


3 phase set up, 3x MP2 48v10KVA

  • With perfect DC wiring and completely balanced busbar
  • PV cabling is all 6mm
  • 16x Pylon US5000 4.- 8kWh batteries, wired in sets of 2x
  • 2x RS450/100 charge controllers (see attached for string layout)
    • All of the above using the following panels; 18x JAM72S20 460/MR - Max theory output = 8.280kw

  • AC Inverter: Solis S5-GC-30k
  • AC solar panels in 3x strings
    • All of the above using the following panels; 24x JAM72S-30-555-GR-F30-EVO2 - Max theory output = 13.32kw
    • There are Tigo optimisers (TS4-A-O) on all of string 2, 3 and some on string 1 where it's possible to get tree shading (not sure this is even needed). These Tigos are not TAP connected and I have no monitoring (but I will be setting this up soon).


  • DC panel layout
  • AC panel layout
  • Wiring diagram

The issue(s):

1) It could be me but 90-95% of the time the AC panels wattage output seems to match the DC panel output, very rarely will is be vastly different.

  • This seems to be regardless of battery SOC (Noting that frequency shift shuts down AC/DC as needed if when SOC is nearly full)

  • There appears to no difference to this when AC load is high or low.

  • The 'AC/DC matching' occurs when frequency is below 50hz

  • There are times when the AC over-shoots the DC PV system; but only happens for a few minutes in most cases.

  • Could there be an issue with Frequency shifting causing this apparent sync?

2) On the DC panels, panel 4 can get shading after midday and morning sun; but I wonder would I get better results combining strings 1 and 2 for a higher voltage?

3) Anyone have any AC suggestions for me to get better output?

4) Tigo Optimisers - I've have been watching and reading so many comments/tests. As mentioned above, they are not TAP connected but I've purchased one so will be checking the firmware on the Tigo's to see if there is any buggy firmware present.

Reference 1
Reference 2
Reference 3

5) Tigo Optimisers - I'm unable to determine if they even work correctly with my panel type or not. Again if anyone has suggestions that would be good.

Thank you.



MPPT Controllerssolarfrequency
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