Thread Derail apology!
TimI to clarify, it's not matching voltage between 2 separate PV strings, it's matching voltage with the same string it's connected to - which is then connected to the Givenergy Inverter.
In my case String 1 is a normal bunch of 9x 340W panels
String 2 is an identical string of 9x panels with this magic box (& batteries) connected between them & the GE Inverter.
It operates as pass through essentially (I can disconnect the battery and it just carries on as if the magic box isn't there) but because it can voltage match it can add in more "virtual PV" to the string - the same as if I had an extra 2.5kW of panels attached to the 9 real ones on that same string.
The GE is none the wiser, all it sees is anywhere between 0 & 5.5kW string of panels (if I want) - I did suggest to GE that a similar magic box could be built for Gen1 people to boost the output of their batteries (basically looping back to the GE Battery) but then Gen 2 kind of negates the need. (Although I can still beat Gen 2 by 1.4kW Discharge)
For how it knows when to hand out additional power there is yet another CT on the incoming supply. If I'm exporting, it sucks up power from the panels (so the GE just thinks it's a bit cloudier than it really is) likewise if i'm importing it pushes out power (so the GE thinks it's sunnier than it really is) - it does however mean my panels often show 2.5kW of solar at 11pm but has required no input from me since i fitted it over a year ago.