Using DIY LifePo4 batteries with Solar Edge inverter...

[quakershaker]

Hi all, hope someone can advise here. Here in the UK (London) I have 4kw solar with Solar Edge inverter (model SE3680H) and I want to build & connect my own battery storage to this system using LifePo4 batteries to store the excess solar production that I dont use during the day so i can power my home after sun has gone down. Has anyone done this previously with Solar Edge inverter ro know if it is possible/doable? I contacted a supplier and he advised against using a DIY battery:

"Dont even think about the DIY option. Especially not with SolarEdge.This is like mixing an Audi with a Renault Engine. Usually doesn't end well. In other words, it wont work. I know this from practice. SolarEdge Works with the 7kW and the 10kW High Voltage LG Resu Chem. If you looking for a cost effective option, try the AC Coupled Solis or (my preference) the AC Coupled Solax."

Any suggestions would be greatly appreciated before I go and buy some LifePo4 batteries from China!! Many thanks, Peter

 

[kernel]

If you ac couple the machine it will work in tandem with a hybrid battery based inverter with ac coupled modes. I dont see why it wouldnt be able to be switched on and off with grid line freq shift. I have not integrated a battery with solar edge yet though either.....

Lithium should be way better than trying to charge lead.

 

[JoeHam]

The supplier is a wanker (the only UK insult I know).

DC volts are DC volts and any inverter could care less where they came from.

If you match the amp hour capacity and voltage of whatever battery he is trying to sell you there cannot be a difference.

You will need BMS of course.

 

[kernel]

The supplier is a wanker (the only UK insult I know).

DC volts are DC volts and any inverter could care less where they came from.

If you match the amp hour capacity and voltage of whatever battery he is trying to sell you there cannot be a difference.

You will need BMS of course.

Wanker, i love it... brit slang.

Many of the inverter systems with a battery partnership have control communications and other hardware and software schemes to control dc output to the battery. Not sure of what ways and languages they are using, but if you want an enphase, magnum, sma or solaredge system with mlpe on the panels to modulate dc output from the array based on load and battery requirements he could definitely be right.

Any listed grid tie inverter will be able to be ac coupled to a hybrid battery inverter.

The magnum with microinverters works this way but can throttle individual module output to keep everything happy instead of cutting pv power for 5 minutes.

In the case of solaredge it uses 400-500v so needs a 400-500v battery and charger and bms or an ac coupled charger.......hybrid inverter. Then you can use whatever battery voltage inverter you like. Also some of the whole house power wall type batteries cannot ouput large power flows amd need to be paralleled.

 

[Gmac04]

Hi Quakershaker
I'm probably looking at the same system here in Dunstable UK.
I believe the Solaredge inverter is a DC to AC device that only converts Solar panel voltage to the mains. I also have 16 panels (4Kw) and my inverter is an SMA inverter. I too have been looking to harvest the spare solar capacity for use in the evening. I presume you receive Feed In Tariff payments and if this is the case you need to leave you system as it is. Once the AC has gone through your FIT meter and gets to the consumer unit you can now connect to a separate AC coupled inverter and battery. A simple all in one solution is available from SOFAR but the battery component is twice the cost of building one yourself

I've watched shed loads of videos and have just ordered 300x 18650 cells to build a battery bank myself. I looked at a couple of AC coupled inverters from Solax and Sofar but both showed a comms link to the batteries (Pylontech and Amass) I contacted the inverter manufacturer and was told the comms link is required to enable the inverter to establish the state of charge via the battery BMS. I couldn't find any videos that showed how this might be done. One option suggested by the manufacturer is to set up the inverter as if the batteries are lead acid as these don't used the comms link, but no details available on how to set up the max charge voltage and low voltage discharging limit. Perhaps someone can shed some light.

 

[Sunshiner]

Hi, did you find a solution to this? I am looking to do the same thing and acknowledge the need for a G98 type approved ac coupled inverter but I dont want to be tied into the manufacturers badged battery cells.

 

[Gmac04]

I did buy the 18650 cells and started to connect them together to form a powerbank. However, once I started to look at the BMS/Inverter communication protocols, I went round in circles tying to get matching information. I sold the cells on eBay. This year, I bought the Sofar AC coupled ME3000SP inverter and the Sofar AMASS GTX5000 battery. Job done.
The reason I went for this solution is threefold:

1. My experience with the "unused" 18650 modem cells wasn't good. Only 85% actually held their rated charge.
2. When I costed in the price of NEW prismatic LiFPO cells, BMS, shipping, Import duty and VAT; the saving from a DIY setup didn't save that much. The big saving comes from installing the system myself.
3. There are so may complaints about buying the prismatic grade A cells and receiving grade B product.

My existing 4Kw panels/inverter setup is untouched so I still get the FIT.
Last month I fitted an extra 2.8Kw of panels and a second small inverter so the AC coupled device now picks up the spare power from both sets of panels. The total grid usage in May was less than 10Kw and at the new cost/Kw rates for electricity in the UK, the payback has reduced considerably.


PS GivEnergy also have a good ready made solution.

 

[loobosh]

The 400 volt batteries are 48v inside it uses a buck inverter bidirectional so if you have a powerwall 1 or LG chem you could tap into it. Or if you are lucky enough to find a dead pack put your own batteries in it or use the electronics on your diy pack. Someone should of made a external buck inverter a long time ago that communicates with storedge. Here in the states 48vdc is the highest volts by code to use on residential systems that's how they can install the battery in the first place.