Swap Sofar charger for Sofar hybrid inverter to add more

[JC_UK]

Hi,

We have a SMA inverter with 16 panels connected and on FIT.
We have added a Sofar ME3000SP charger and pylontech batteries.

The DNO say we can add another 3kw of generation to the system.

I am thinking of a swapping the 3KW Sofar charger for a 6kw Sofar Hybrid inverter and connect the battery storage to the hybrid inverter.
This will allow a further 6kw of generation, over the 3kw that the DNO will allow with the sofar charger in the system.

Does anyone know if the Sofar Hybrid inverter will direct all surplus power to the connected batteries or only surplus power from the connected solar panels?

Many thanks
JC

[Tinbum]

Not sure but if it doesn't you can always leave the ME3000 in as well but that would require some thinking about 2 chargers on 1 pack.

[nowty]

I have a ME3000SP in my system which I have used as a dumb battery charger in timed mode, in winter, set at an extra 50A of battery charging on top of the 120A I get from my SMA sunny Island battery inverter. I do however, have a battery bank size, cables, fuses and isolators capable of such power and it is set to charge to a lower voltage so it drops out at around 70% SOC.

I love copper and bolt down fuses.


On the Octopus Intelligent tariff I get 6 hours of off peak charging so I don't actually need or use the ME3000SP anymore. But if I had to go back to Octopus Go on a 4 hour slot, then I need the extra charging power for the shorter slot time.

[Ken]

So you are thinking to feed the new panels to the hybrid inverter and then to the batts. If you remove the Sofar charger where/how would you connect the SMA inverter output to the batts ? The hybrid inverter is fed with DC current and you cannot attach the output of the SMA which is AC directly to the batts without a charger.

So the question is can one have 2 chargers supplying one batt bank. I dont know but it seems doubtful ??

[nowty]

So the question is can one have 2 chargers supplying one batt bank. I dont know but it seems doubtful ??

Yes you can but the stats on the inverter(s) will be all over the place and at least one will have to run in dumb mode (no BMS connection) unless you utilise some fancy comms.

Its quite common use a DC charge controller to connect a second charging source to a battery stack, but less so using a second grid tie battery inverter unless they are set up as a master / slave configuration with comms between the two.

As Tinbum has pointed out, you have to know what you are doing and be careful not to exceed charge and voltage limits of your system, like batteries, cables and isolators.

[Tinbum]

So the question is can one have 2 chargers supplying one batt bank. I dont know but it seems doubtful ??

Yes you can. Some inverters are designed for it and have a communication cable between them to control the charging / discharge. My 3 SMA sunny islands are linked like this.

You can just use a junction box on the CAN cable so it has 3 plugs, turn off the CAN resistor in the Pylon Battery DIP switch settings and that should work but current (A) settings will be incorrect. If you have a really large battery pack it probably wouldn't be a problem but certainly not recommended for small packs. Say you had 3 x US3000c the max current that can accept is 111A (37A x 3), now if your inverters were 3KW each they could push out 120A (60A x 2). I know people will say that, for example, the current will taper off anyway, but that's only when nearing fully charged. I work on the principle that the battery pack manufactures put a max charge current in for a reason, and im sure they could see if you had exceeded it if it came to a warranty claim.

I have a very large pack but I still alter the CAN settings so I can't possibly overcharge. The SMA inverters are really good in that they report, over CAN, the current they put out, my Eltek chargers do the same but the Sofar inverters don't so I also have to use RS485 communication with them to get that data. (Sofar do actually transmit on the CAN id but they populate it with 0x00 's and despite asking they won't add the data even though I'm certain it would only require a slight firmware update).