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DIY Grid Tied Storage

Kai

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Joined
Mar 17, 2021
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3
Has Anyone got experience building and connecting a grid tied Lifepo4? and connecting to a 230-250v grid tied inverter.

I have access to the wholesale price for my grid power. This has potential to vary between negative price (they pay you to use power) and occasionally extreme high prices when the grid is under load. I'm going to build a home battery and was looking for ways to grid couple it with an approved grid tie inverter however most of them seem to have battery connections of 100 to 600 volts. for this system I was hoping to use 24V as I have a bunch of 24v components.
 
Welcome to the forums Kai,

I'm surprised you didn't get any hits on this, I guess most of the battery builders are off-grid. You might check out @GXMnow's thread, he's in SoCal and has his setup trying to keep from importing during high tariffs and chronically his struggle with Enphase and Schneider.
 
G'day Kai, I am thinking of doing this.
I have 15kW of grid connected solar, but am export limited to 5kW at the meter by my utility. This means I often have lots of power 'lost' that I'd like to capture and use at night. I already control my electric storage hot water tank to consume free

I looked at building a HV (320V) battery pack and connecting directly to a conventional grid-tie solar inverter at the solar input. Control the battery discharge using the inverter limit over modbus. You can use conventional inverters which you can get dirt cheap second hand here on Facebook marketplace in Australia. Problems are BMS, lots of little batteries are more expensive then a few large batteries and finding a high KW HV charger. I wanted to charge at 5kW peak.

So now I am thinking 48V system with a dedicated storage inverter. Probably a Goodwe GW-GW5000S-BP which I can get for about $AU1450. That can push or pull 100A at 48V. It would probably be cheaper then the cost of the HV charger I would have to build, and is safe and controllable.

We will see how I go, just getting quotes for batteries now and need to sort a BMS that will talk CAN to the storage inverter.

What are you up to?
 
G'day Kai, I am thinking of doing this.
I have 15kW of grid connected solar, but am export limited to 5kW at the meter by my utility. This means I often have lots of power 'lost' that I'd like to capture and use at night. I already control my electric storage hot water tank to consume free

I looked at building a HV (320V) battery pack and connecting directly to a conventional grid-tie solar inverter at the solar input. Control the battery discharge using the inverter limit over modbus. You can use conventional inverters which you can get dirt cheap second hand here on Facebook marketplace in Australia. Problems are BMS, lots of little batteries are more expensive then a few large batteries and finding a high KW HV charger. I wanted to charge at 5kW peak.

So now I am thinking 48V system with a dedicated storage inverter. Probably a Goodwe GW-GW5000S-BP which I can get for about $AU1450. That can push or pull 100A at 48V. It would probably be cheaper then the cost of the HV charger I would have to build, and is safe and controllable.

We will see how I go, just getting quotes for batteries now and need to sort a BMS that will talk CAN to the storage inverter.

What are you up to?
Hey Will

Bit of a thread dig but how did you go with the goodwe inverter setup. I'm about to pull the trigger with the same setup and 15kw of lithium storage. It seems the only viable affordable option for grid tied retrofit of a battery system alongside an already installed solar system?
 
I can tell you that WIll went ahead with this and has it working well. Head over to the Australia Whirlpool forums where will provides some details of his system in a thread that i started about Grid Arbitrage

Craig
 
Sorry, only just saw the question.

Yeah, works well. Went with a Seplos BMS and the Goodwe inverter. I control the whole setup with an ESP8266 and a RS 485 converter to talk modbus to the inverter.
 
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