At last a teardown of a 6 kW solar inverter, the Fronius IG Plus 2LT-2. Two phased system split into two inverter boards, based on TO-247 devices in the power electronics section. As always I would like to invite you to join the discussion of this project. And many other exciting DIY electronics projects at https://highvoltageforum.net
If you want to read about more and other solar inverter teardowns, check out. 10 kW Sirio 10000P Solar Inverter Teardown. Or ABB TRIO 20 kW Solar Inverter – Unboxing and Teardown. Or my own 750 Watt solar panel setup with battery charger and inverter. 750W Victron Solar Project – 60 Days Performance – Part 4.
Inside the Fronius IG Plus 2LT
The 2LT-2 model is connected to mains grid on two phases. The inverter is made up from two identical single phase inverters, connecting to L1+N and L2+N. Each inverter capable of 3 kW output power, for a total of 6 kW. A qualified guess would be that the 3 phase version can output 9 kW.
All magnetic components are nicely placed on a metal plate on top of the heat sink tunnels. Whereas an internal fan cools the magnetic components with the surrounding air. The heat sink tunnel for the power electronics is cooled with external intake air and external exhaust.
The DC and AC busses, run as bare copper busbar underneath the printed circuit boards. The copper busbar runs in a standard plastic cassette prepared for the larger 3 phase versions. Overall design seems to scalable from 1 phase to 3 phase. 1 phase 3 kW, to 2 phase 6 kW and 3 phase 9 kW, adding multiples of identical components.
To sum up the power electronics, it’s MOSFET to Schottky Diodes to IGBT. Firstly it is Microsemi APT94N65B2C3G MOSFET driving a isolation transformer from Solar DC BUS to boost voltage. APT94N65B2C3G specifications: 650V, 94A, 282A pulsed, on-resistance of 35mΩ and total gate charge 580nC. Secondly rectifying diodes is Cree Schottky C2D10120 with specifications of 1200V, 18A and 100A pulsed. Thirdly it is Fairchild FGH40N60 IGBT FGH40N60 from boosted DC BUS to output inductors. FGH40N60 specifications: 600 V, 80 A, 120 A pulsed, Vce(sat) voltage of 2.5 V and total gate drive energy 1.61 mJ.
