10 kW PV System House Inverter Build

[bigolbug]

I am working on a solar system for my house. I would like to build the inverter and would appreciate some input. The base specs of the inverter need to be 10 kW inverter two phase running off of 48V DC. It can be 5000W on each phase. I would like it to sync with and switch over to mains if the battery's drop below 50% capacity. I am very familiar with raspberry pi and Arduino. I have so many questions but for starters I need to know what would be a suitable transformer and would any of the software and schematics that are available be usable in my build. Thank you for you time and consideration.

[joromy]

I can imagine a whole world of regulatory problems if you want to do a grid tie inverter.
UL 1741 and IEEE 1547 are the standards you need to follow, for a grid tie inverter.

I haven't thought about, switching between grid and your own power, but a grid tied one would work better, I think....

[bigolbug]

I do not intend to build a grid tied inverter. I just want it to sync with the grid so that if the inverter needs to switch the system over to grid power (Batteries deplete to 50%) it can do so with minimal fluctuation. It really is more of a luxury vs a necessity. I would think with a Op amp comparator it would not be to much circuitry.

[NiHaoMike]

I'm working on a "zero export" inverter based on a Gen 3 Prius inverter. (It supplies power to the AC lines like a grid tie inverter but it carefully controls how much it supplies so that none of it goes onto the grid, rather everything injected is immediately used by the loads.) The low level control is based around a FPGA since that allows the fastest response to the load signal. Adding even more to the complexity and the need for the FPGA is that the current sensors connect via PLC in order to minimize the changes to home wiring needed.

If you want to take the easy route, you could just connect the mains input to the DC bus through a rectifier. Then the inverter itself only needs to output AC all the time, easily done with a STM32. Some V/Hz control is very worthwhile if there are any large motor loads.

At 5kW, I would suggest going for more than 48V on the battery, since such a large pack will almost certainly have multiple cells in parallel, at which point you'll do better having more cells in series and fewer in parallel in order to reduce the current and the conversion ratio needed for the buck/boost stage.