Is it possible to change the ESS settings to enable the use of just one 2.4kwh or 3.0kwh Pylon battery. We need to keep cost down but really want to use Victron as it’s been so good in our VW California camper van!
Thanks
Andrew.
asked
One Pylon Battery with Multiplus II ESS
There are no ESS settings which have to be changed whether you have 1 or 10 batteries.
You haven't said which multi, a single battery isn't recommended for larger inverters, especially off grid.
The recommendations are here: https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom
You can reduce inverter limits in ESS to keep the battery discharging within limits, that's about it.
Many thanks for your response, we were considering the Multiplus II 3000VA 48v with either one pylon 2000 2.4 kWh or one pylon 3000 3.5kwh.
This would be for a grid tied system ac coupled on a uk feed in tariff.
Does anyone know what the safe maximum discharge rate would be for either of the above two batteries and where the settings are changed in the multiplus software?
Thanks
Andrew.
The battery will set its own limits via the BMS. You can't limit discharge on the multi, only charge but that is overridden anyway. ESS can limit how much power it will use versus grid.
Read the link I sent, it has the setup and everything you need.
The only time there can be an issue is if grid is lost and the battery has to sink or supply sudden changes in load.
2 batteries are recommended, but one is ok for grid attached, trade off is the possibility of instability if grid is lost or at low states of charge.
We never get grid failures in this part of the UK so if you think one battery is a possibility, that sounds very promising for what we need. Please can you explain why one battery is a possibility when it is recommended two are used?
I see the attachment recommends: "These are suggestions for reliable operation for single phase off grid and are not specified by Pylontech".
So do you have to limit the amount of instantaneous power the Multiplus II takes from the battery? I understand the 3000VA multi can give approx 2.4kw at any given time, does this have to be reduced in any settings if one battery is used?
Are there any schematic wiring diagrams available for AC coupling to an existing solar PV system with Sunnyboy SMA inverter on a UK feed in tariff?
Thanks for all your advice, i's much appreciated and is why we want to go for Victron.
Andrew.
As @nickdb says, the recommendations are quite conservative and for good reasons. A good rule of thumb is 2hrs endurance at rated power.
We have a Multi 5k with 7.1 kWh of Pylontech which is approx twice the system capacity you are proposing so about the same ratio of battery to inverter. I would ideally add another 3.55kWh module but they are not available atm. Our experience is that the battery cannot meet the full inverter draw if the SoC is less than 20%, and quite often runs out in the evening, but it recovers automatically and its State of Health is still 100% after 5 months.
If you are concerned to protect the battery more then you can always reduce the inverter power setting in ESS to less than the max 2.4kW, this will reduce the battery drain but not affect the passthrough power capability.
To be clear I would encourage you to use 2.
Inverters can deliver peaks and while 1 pack is sufficient to cover a "normal" inverter load, you need to consider a broader operating environment.
Batteries tend to have voltage drop at lower levels of charge and under higher loads, so if you intend taking the battery down to it's lower limits, you may find ESS or the BMS cutting out.
With a reliable grid, the system can manage exceptions in load via that connection. If it were to fail, your battery must take up the slack, and in some circumstances this can trigger BMS intervention.
So your compromise for saving cost is risking stability at the edges of the performance envelope.
This is why the recommendations exist - to guarantee stability.
If you find you are draining the battery too quickly or hitting limits, the ESS inverter limit sets the max (while grid is operational) it will use, and tops up from grid.
There are plenty of docs on PV inverters:
https://www.victronenergy.com/live/ccgx:ccgx_sma
https://www.victronenergy.com/live/ac_coupling:start
If you aren't used to victron, sign up on the professional site and run through all the training videos. There is good stuff in there - annoying aussie bloke aside ;)
Many thanks for your expert opinions it's really helpful. We may consider a pylon us5000c now to cover stability and the performance envelope. Just one more question....
What is the minimum amount of excess solar generation (watts) required for the Multiplus II to divert to charge the batteries? Our solar immersion diversion takes even low levels of excess, possibly as low as 100w.
Thanks,
Andrew.
Here are some specs for the US5000 against the US2000, does the US5000 look ok?
Pylon 5000 single 4.8kwh battery spec
| Charge rate (A) | 80A recommended continuous, 100A maximum continuous, 101-120A for 15min, 121-200A for 15s |
| Discharge rate (A) | 80A recommended continuous, 100A maximum continuous, 101-120A for 15min, 121-200A for 15s |
Pylon 2000 2.4kwh battery spec (minimum of two as recommended)
| Charge rate (A) | 25A continuous, 50-89A for 60s, 90-200A for 15s |
| Discharge rate (A) | 25A continuous, 50-89A for 60s, 90-200A for 15s |
The max charging current of the 48/3000/35-32 is 35A so either battery choice is fine on that score.
AFAIK there is no minimum power, it is not quantised.
You may want to consider whether to give the priority to the immersion heater or the batteries, each has its merits. You can achieve the latter by making sure the i/h diverter's current sensor is nearer to the grid connection point than the inverter's is (and conversly).
Another major system consideration is whether to have your solar inverter on the AC-In or AC-Out side of the inverter. If the latter it will continue to operate in a power cut, but cannot be higher in power than the inverter itself (1:1 rule). If you have already got more than 2kW of PV it would exceed the charging power limitation (35A x 48V + some conversion loss) so you have no choice!
