Introduction / Important Note
The Sol-Ark inverter is a powerful, flexible, USA-grid-approved device.
This article explains how to interface the Sol-Ark 'Low Voltage' (48V DC battery bus) product line to Redflow BMS+ZBM clusters.
This documentation is limited to explaining the differences and requirements to interface Redflow ZBMs rather than Lead-Acid or Lithium batteries into an otherwise standard Sol-Ark based energy system.
If you plan to integrate Sol-Ark products into energy systems, you need to obtain appropriate training to do so from Sol-Ark directly. Redflow does not offer Sol-Ark training.
Note that Sol-Ark offers online training (both live and pre-recorded) on their web site:- start here
For successful operation:
- The Redflow BMS must be running BMS version 1.12 or later
- The Sol-Ark inverter/charger must be running Sol-Ark version 6216 or later
The Redflow BMS must be cabled to the Sol-Ark device using a CANBus cable.
Wire this cable in accordance with Sol-Ark manual for your chosen product and the labelled BMS CAN_H, CAN_L and Ground terminals.
There is an RJ45 CANBus socket on the Sol-Ark device. The pinout of the Sol-Ark RJ45 CANBus socket various between Sol-Ark models, so check the manual for your specific model to ensure you are wiring the correct pins to the BMS.
For instance, on the 'Outdoor' Sol-Ark 5k/8k/12k models, CAN_H, CAN_L and Ground are pins 4, 5 and 6 respectively:
The ground pin is actually optional - CANBus cables will work without it.
Redflow BMS Configuration
There is no special configuration requirement on the Redflow BMS side!
Just make sure the CANBus control output is enabled (it is enabled by default) and 'it just works'.
Review all configuration pages and consider appropriate settings for your Redflow battery array.
Visit especially all tabs under the 'Batt Setup' page, and make sure that values are appropriate for your situation.
Some key and critical values to configure are on the first ('Batt') tab (as per the image below):
- Batt Capacity in Ah set to "Number of ZBM's x 200"
- Max A Charge set appropriately (it acts as a global constraint that overrides CANBus-sent values)
- Max A Discharge set appropriately (same point)
- 'Use Batt % charged' is checked
- 'BMS Lithium Batt' is checked (The numeric value specified should remain at the default, i.e. '00')
- 'Activate Battery' is checked
Verifying CANBus Communication
You can verify that the Redflow BMS is sending CANBus data and that the Sol-Ark is properly 'hearing' it by using the 'Li-Batt Info button' on the main menu page. If communication is operating correctly, you will see a set of CANBus values consistent with the information rendered on the Redflow BMS status web page (see example below).
A page display here that is showing a different output format to the below (and a lack of useful data) indicates that the CANBus communication process is not yet operating correctly.
Battery "Activation" (starting up a discharged Redflow array)
The Sol-Ark product has a 'Battery Activation' function, designed to recover batteries that have run flat. This function operates to successfully bring up a Redflow battery array from empty (zero volts).
This 'Activation' function must be enabled in the Sol-Ark on-screen interface ("Batt Setup" page, "Activate Battery" checkbox).
The battery 'Activation' function does not commence operation until the Sol-Ark unit has been powered up for ten minutes.
At the ten minute mark (from either AC grid power or DC Solar Power), and providing the unit has a reason to charge generally (see next point), the system starts to slowly ramp up the DC battery bus voltage.
The process of ramping this voltage can take a few minutes, before the voltage rises to the point where the Redflow system is able to complete its normal 'bubble purge' and 'pre-charge' functions and then commence normal battery functionality.
The activation function will not commence at the ten minute mark (or later) until the Sol-Ark has a reason to charge the battery.
Two examples of conditions that will lead to the Sol-Ark charging the battery are:
- DC solar is present at a power level exceeding local site energy demands (i.e. 'surplus solar' exists)
- There is an AC grid connected and the system has been programmed to undertake a time-of-day based AC grid charging period (via the "Grid Param" page, "Limiter" tab).
Here's an example of the 'Limiter' tab - configured for a set of time-based periods of grid charge and grid discharge of the battery:
- If the battery electrolyte temperature is below 15C the system won't be able to complete the initial activation from empty until that temperature rises above 15C. Once the battery starts to charge, it can keep itself warm 'on its own' from then on (even if the ambient temperature falls far below 15C).
- If the unit is being tested in a 50hz country (ie. not in the USA) and will not "grid charge", please note that changing the grid frequency to 50hz ("Grid Param" page, "Grid Input" tab) is not sufficient on its own; You also need to change the acceptable frequency limits in Hz (on the same page), as they do not automatically change to '50Hz appropriate' values on their own.