The operational manual for the above unit states a nominal PV power of 1000 watts (12v). The specifications note- 1a) The solar charger will limit input power if more PV power is connected. A common formula I have run across in solar design for input/output of a solar charger is 1000w/12volts= 83.…

Yes, The unit will happily limit input power AS LONG as you also stay under the MAX input current of 70A. your example of 12V - I would assume that you intend using this on a 12V system? So the Max output power would be typ 70A @ 14V or 980W. your input to the MPPT can be as high as 150V (for the …

I own a SmartSolar 250/100 and a 250/70, and regularly overpanel the inputs with more solar than the nominal wattage. I do use a small quiet fan below them to keep them cool. Both devices adjust the load on the PV input side so that the output current does not exceed 100A (for the 250/100) or 70A (…

Do you exceed the short circuit current? I was looking at this with another user. The 70 can only take 35A and the 85-100 can do 70A in. [image]

I do not exceed the short circuit current on either the 250/100 or 250/70. On the 250/70 with the 35A limit, I get very close at 33.4A max ever seen, with Isc at 34. something,

I offer this correction: [image] The 70 can take Max 50A in on the PV side. The reason for this limitation is the size of the protection FET - and maybe other issues… The clamping FET limits the max input voltage, if it sees too much current, it won’t turn off again. ( similarly the series swi…

Not to muddy the waters, but I’ve read that the reverse-polarity protection circuit has the Isc current limitation by shorting the input with a FET, in case you hook it up backwards. In other words, don’t do that and it will be fine. At one time Victron apparently said this in community, but I canno…

Yes, the Voltage clipping fet also implicitly provides revers polarity protection due to the built in diode in the N channel fet. So same device= same current limit.

@MikeD , Am I correct in understanding that it’s ‘safe’ to go to an Isc of 50A on the 250/70? As in that the 150/70 and the 250/70 should have the same Isc limit?

I’ve not checked the data sheet for the 250/70, but yes, 50A is safe for the 150/70. The data sheets can be downloaded from Victron, and the max Isc is specified there.

MPPT 250/70 tr Maximum PV wattage

DIY

Murbles 25 February 2025 20:42 10

Yes, I have a 12 volt system with the phoenix 12/1200 inverter.
Thanks a lot for the clarifications!! This has been great info.

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MPPT 250/70 tr Maximum PV wattage

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