Recently, one of the fleet captain commented that he felt the solar charging was being limited for no apparent reason.
The boat design includes:
- 7 MPPT’s with panel capacity of up to 13 kW
- 3 x5 KVA 220V Quattro running in Inverter mode most of the time.
- 1 MG Battery banks of consisting of 2 BMS with 400Ah/25.2V each and a MG Battery Combiner
- a Cerbo GX running DVCC.
But it also has:
- 3 MG HV Battery Bank @378V/200Ah running in combined mode
- 7.5 - 9 kW Bidirectional DCDC to shuttle energy between the HV Battery and the LV battery
The system design uses the 24V battery as a buffer for the energy storage. During the day, once the 24V Battery is about the Hi threshold voltage the system export the excess energy to the HV battery. At night, when the 24V battery voltage is below the Lo threshold, the DcDC transfer the Energy from the HV to the 24V battery to maintain that minimum voltage.
Specifically he captain, mentioned he never seem to get more than 4 to 5 kW from the solar transferred to the HV system. He observed that during the day when close to full charge, the amount of solar power generated would decrease and depend on the Quattro Inverter power consumption. When the Quattro Inverter demand increase, the Solar power you Increase by the same a mount and return to same original power, once the Inverter demand disappeared.
In the graph below we can clearly see the solar power being Limited:
I have read an experienced before that DVCC only controls the MPPT’s and the Quattro charge current and when we use Skylla, we sometimes can have issue because the system can charge the battery with more current than what the CCL limit would allow as those external chargers are not accounted for. This is also what is happening here:
The SmartLink, sends A CCL of 200A. The DVCC limits the MPPT’s current to the CCL Limit + Inverter current. So when the Inverter load increases, the MPPT power increase as observed by the captain. The issue however is that CCL is suppose to be the maximum CHARGE current at least in my understanding of the Purpose. But the DCDC (light Blue) is exporting most of the current produced by the Solar panel to the HV battery resulting of a Net CHARGE current of 0 (Orange) and in the process artificially limiting the MPPT potential.
Is there any way we could allow the DVCC to offset the MPPT charge current limit with the DC Current used by the system?
