I am planning the following system,
2 x VICTRON MULTIPLUS-II 48/5000/70-50 connected in parallel.
24 x 530W JA solar panels controlled by 2 x SMARTSOLAR MPPT 250/100 VICTRON.
A Battery bank made up of 6 x 4.8KWH 48V PYLONTECH US5000.
My questions are as follows
1, I have read that Victron can use the BMS used in the Pylontech batteries, so do I need a shunt as the system is able to tell the various states of the battery bank.
2, Do I need a Cerbo unit ?
As far as I am know, the inverter talks directly to the battery bank. Can the MPPT controllers talk directly to the inverter as well ?
Am I able to access all the settings of the system using a computer or do I need the Cerbo to be the access hub ?
Finally, I hope to add 2 small wind turbines to this system to improve winter performance.
Has anyone any experience of that ?
Can the MPPT wind controllers link and communicate with the solar MPPT controllers and inverters or do they need to be able to communicate ?
You certainly need a Venus GX unit, be it a Cerbo or other device.
The Multiplus DOES NOT “talk” to the battery bank, it has no CAN bus input. This is what the Cerbo /GX device does. It also controls the Solar charger too.
OK, so using MPPT’s with wind turbines - there are a lot of posts here about that topic. Basically it depends on the wind turbine type: most of these will over-speed in strong winds with no load - this means a dump load or other breaking system needs to be used. The Victron MPPT’s reduce the load on the source as the battery gets to full charge and they have no way of triggering the dump load or break system. This can be done with adding node red code to the Cerbo.
Some Wind gens come with their own controllers including the dump load. However, you also need a remote input to them so as the Cerbo can shut the charging down when the BMS requests this.
When lithium batteries get to full charge, one cell always gets to full charge before the others, the balancing usually takes care of this. However, it can mean that the charge needs to be limited BEFORE the absorption voltage is reached. This is why all charge sources need to be controlled by a central device that processes the BMS data.
It will answer most questions.
Then familiarise yourself with the ESS design manual and the wiring unlimited guide.
It will allow you to ask more focused questions.
There are also few questions that haven’t already been asked, so digging around on the community will provide a wealth of information.
My peak load could be 10 or 11 kw but normal operation it will be below 5kw, so I thought 2 x 5kw would be better. I can swap them over from slave to master regularly to ensure similar number of hours work and also if one does break down, we can still keep our system running which an important consideration as we are going to be offgrid.
If you have an better ideas or reasons why you think my method is not as good as a 10kw inverter then I would love to hear them.
As I have said at the beginning of this thread, I am learning
Understood. Which is why there is the warning, a parallel set up is not for beginners. They are headaches especially getting the current sharing right. So basically you don’t you don’t have 2x5kVa you may end up with 7.5kVa. it is possible to get it much closer but if you soend time reading up you will see headaches from these types of set ups. Then over time one unit 'weaes faster than the other. You idwa of swapping them will literally mean a physical swap in wiring position and a re set up.
Agree, with a parallel system, one inverter fails, the whole system shuts down anyway - until reconfigured. Doing that is a pain.
However, I’ve never found setting up a parallel system to be a problem as long as the basic requirements are met. Been using parallel systems for last 10 years.
if you use 2 x 5kVA, and want a little more power, it is cheaper to add a third. With the 10kVA, then you have to increase power by a factor of 2: so end up with 20kVA instead of 15. Also other hardware is needed to parallel the larger inverters.
It shuts down until reconfigured, and you then need to get out the laptop and Mk3 to do that. you may also need to consider an emergency standby inverter of a few '00 W to provide ac whilst this goes on; should you get a failure, Murphy’s law says middle of a black night.
I have seen, that for parallel connection, all invertors have to be the same make and model with the same version of firmware. So if I am purchasing all at the same time, that shouldn’t be an issue but I will talk to the distributor just to be sure.
Not just the same make and model but within 6 months of each other in production. There are sometimes hardware revisions and then a parallel set up becomes less sharey…
So if you do decide then at a later date to add a further 5 you need to know the distributor that you intend to do so, so they keep a model in the manufacturing date range.
Time based additions also become a thing, after a certain amount of time/use also adding in parallel becomes a bit more problematic because of components aging.