GTI Inverter headaches

Just a quick post to update readers on the avenues I'm exploring about this problem.

One possible solution I have found is that some Chinese inverters use an ATMega controller CPU. There are a group of great guys in Germany who have discovered these, interfaced to the CPU (this type of CPU is easy to reprogram) and written their own version of the firmware that allows the GTI to be reliably used with a battery.

I found this post here that refers to the German forum and details the code a little
OpenEnergyMonitor.org
http://openenergymonitor.org/emon/node/1658#comment-21742

The German forum is dasWindrad.de, here is the linked post
http://www.daswindrad.de/forum/viewtopic.php?f=19&t=860&sid=b206245d4f6cf8c43dd314799e57875a&start=80

which could quite possibly be the answer to my problems if I spoke German, which I don't.

The GTIs which they say use these ATMega CPUs are made by PowerJack.

A blog from what appears to be a PowerJack employee (in the design dept?) is here
http://powerjack888.blogspot.co.uk/2014/05/lf-psw-power-inverter-from-power-jack_26.html

And I've send a message to the fellow, Chang Jack, asking if he can point out which 2014 products use the ATMega CPU.

Another possibility is REUK:-
http://www.reuk.co.uk/Grid-Tie-Inverters.htm

This chap built his own GTI and has made all the designs and source code available for anyone to build their own GTI, and obviously that will be easy to disable MPPT and optimise it to work off a 24V battery, but it's not exactly scalable if I want 10 inverters.

I will keep this blog updated when / if I hear back from my enquiries.

Oh, one last thing I intend to try with the little 500W inverters I have (that don't recognise the 26V from the battery as enough voltage to start working) is to adjust their voltage divider (there's a convenient potentiometer) to see if I can persuade them to at least start, and then see how their MPPT behaves with a low resistance (the battery) supply.