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maxs asked

SmartSolar MPPT output protection (OVP) against single component (statistical/random) failure

Dear forum,

how is the battery output of the solar charge controller protected against single component failures? My concern is that a single failure can result in a higher output voltage than the programmed charge characteristic. When converting a 100V solar voltage down to 12/24V. Since 12/24V BMS MOSFET blocking voltage is 40V-60V V_DS, a shoot through of the charger will result in a failure of BMS, battery and loads. Major internal components to look on might be:

  1. fail short of the switching transistor in step-down application. Or is an isolated topology used?
  2. micro controller crash/fault. Is an internal/external watchdog stopping the swichting?
  3. Drift or failures in AD-converters, references, or voltage deviders and general failure of the control loop. Is there an independet output OVP?
  4. Some kind of fusebraker/crowbar on the battery side?

Is some FMEA available to proove output OVP function under single fault conditions?

Where do I find MTTF values for victron products?

regards

Max

overvoltage
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2 Answers
Johannes Boonstra (Victron Energy Staff) avatar image
Johannes Boonstra (Victron Energy Staff) answered ·

Hi Maxs, the MPPT is not isolated but has an addition circuitry to measure/test the MPPT tracker itself and as soon as values are out of range the addition circuitry will be able to stop power to the converter.Therefore there is no risk high voltage can end up at the battery side. Thats also why there is a maximal input current values, as this is the max the addition circuit can stop. So respect the maximal values as stated in the datasheets and the MPPT will be safe under all conditions.


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maxs avatar image
maxs answered ·

Hi Johannes and thx for your answer. Ofc I respect the limitis given in the datasheet. My moduls have 7.4A short circuit current in total and 52V max. voltage (open circuit) parallel connection. I consider to fuse the grid side with 10A 80VDC fuse and the batteryside with 40A 42VDC fuse. I will use the smart solar 100/30 for a 12V battery system.

The protection you mentioned can also handle a MOSFET short circuit and a micro controller crash?

Is any block circuit diagram available?

Does the product provide an internal varistor or TVs diode on the PV side?

best regards

Max

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