The grid tie solar inverter SMA Sunny Boy SB2500 is a beautifully designed transformer isolated grid tie inverter. It is probably possible to convert it to an off grid batter inverter by reprogramming or redesigning the logic board
Checkout my [hackaday.io](https://hackaday.io/project/183357-grid-tie-inverter-sma-sunny-boy-sb2500-openlogic) page for pictures of the inside of the inverter and a project log.
The inverter has an H-bridge with 4 IGBTs (SKW30NF60) driven by IR2113S mosfet drivers. These drive an 2mH inductor + 4.7uF capacitor step down converter and then a isolation transformer 153V primary/230V secondary 9.6A. On the grid side are three safety relais, EMC filtering and a measurement transformer for the logic board the measure the grid voltages.
All the logic is powered from the DC side, several voltages are generated using a switching power converter which generates all the drive voltages for the IGBT drivers and the logi board.
The logic board contains an SAFC808 microcontroller, probably with an interchangable AT70C020, 2 MBit memory chip, for grid monitoring and sequencing. A DSP56F803 from Freescale provides the switching waveforms.
The src folder can contain the Freescale DSP code.
The datasheets folder contains datasheets of most of the electronic parts in the inverter.
# Already known
* Switching frequency 16khz
* 250 - 600VDC max input voltage range
* 2200W nominal power
* It is probably challenging to reuse the logic board, as one of the microcontrollers is OTP, maybe it can be bridged and only the DSP used. But then you need a [Freescale USB TAP](https://www.nxp.com/docs/en/user-guide/CWH-UTP-UG.pdf) JTAG programmer to program the DSP. The development environment is not easy to download, but it looks easy to use.
* The [DEFCON 18 badge](https://media.defcon.org/DEF%20CON%2018/DEF%20CON%2018%20badge/) has used the same development environment and might be a good place to download the development environment and some general guide.
# Already done
* Basic pinout of the logic board connection in Kicad
* Basic layout of the power board important parts in Kicad
# TODO
* Check if pinout is correct by measuring the voltages on the logic board connector
* Check all voltage ranges of the voltage measurements on the logic board connector
* Try to reprogram logic board
* Or design new logic board
# Interesting links
* [Arduino based grid tie inverter repo](https://github.com/MartinStokroos/openMicroInverter)
* [Pic based grid tie inverter repo](https://github.com/rajeshfarswan/UDQ-GRID-1P
* [STM based grid tie inverter repo](https://github.com/fotherja/Grid_Tie_Inverter)
* [STM based grid tie inverter 2 repo](https://github.com/fotherja/Grid_Tie_Inverter_2)
* [TIVA-C based grid tie inverter](https://github.com/srpoyrek/NIVAS)
