Hello,
I am creating a device implementation for the AMPT String Optimizer / ESS DC Charger:
https://www.ampt.com/products/string-optimizers/
This is a system where there are DC-DC converters for each solar string (MPPT trackers) connected to a common DC bus of the ESS. I think the OpenEMS API / Nature that best represents this is EssDcCharger.
The Modbus interface for the system is provided by an AMPT communications unit. This communicates wirelessly with the distributed DC-DC converters and provides all data in one interface.
You can see product information here:
https://www.ampt.com/products/ampt-cu/
And the instructions containing Modbus protocol here:
The Modbus protocol returns data on a per-string basis, and the number of strings is dynamic depending on how many optimizers are connected with the communications unit.
I see two ways to approach the implementation:
- Implement a dynamic system where a device implementing
EssDcChargeris instantiated per string / optimizer. This would require the devices to be created dynamically depending on the valueN(number of strings) that is read in the opening Modbus block. - Add logic into the device implementation to represent all strings together as a single
EssDcCharger. This would sum the current and power across all strings and represent this as a single device.
To my mind, approach 1 would provide enhanced data visibility as the performance of different strings would be more easy to visualise. However, the implementation would be more complex.
I would like to get the community’s views on this question and whether this approach is practical.
Has anyone implemented something like this before?