question

okelaa avatar image
okelaa asked

MPPT charges the battery while generator covers the AC load

In case of AC load and while the generator is running the PV power is not re-directed to cover the AC load, thereby taking off the load from the generator. The MPPT continues charging the battery while AC load should be covered first (see the screenshot below).

I am kindly looking for advice if the system can be reconfigured to address such situations.

1680781135082.png

Main equipment:

Isolated SmartSolar charge controller MPPT RS 450/100 - Tr

Inverter Quattro 48V/5000VA/70AMP

AGM deep cycle 12V 240Ah x 8




MPPT SmartSolar
1680781135082.png (147.6 KiB)
1 comment
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Alexandra avatar image Alexandra ♦ commented ·
It is to some degree, only 752w of the 1062w production is going to battery.

And your generator load is lower than your AC load figure.

It is more efficient to charge from the DC mppts than the AC generator anyway.

As far as I can see everything is working as efficiently as it can.

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3 Answers
okelaa avatar image
okelaa answered ·

Thank you for your reply!

So the system is working effectively. Great!

Kind regards,

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ahtrimble avatar image
ahtrimble answered ·

I ran the numbers:

Your AC loads are 2340w.

Your genset is providing 2140w.

Your MPPTs are providing 1062w.

2340 - (2140+1062) = 862w of remaining power being generated.

Then your screen shot shows 752w going into the battery bank.

That leaves 110w unaccounted for which at your battery voltage is less than 2amps. I wouldn't worry about that unless there is something else going on.

I do have a question...if you have a 48v system, do you often see your voltage at 59.67v?


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okelaa avatar image
okelaa answered ·

Thank you for your thoughts!

Yes, when the battery bank is at a given temperature 4 degrees Celcius, the absorption voltage must be 59,7V as an average.

At -10C it was knowingly even higher 61V. Electrochemical reaction is slow and incomplete with low temperatures, so the battery gets continuously uncharged.

Therefore, my settings contain temperature compensation 4mV/Cell (24mV/℃ for 12V battery) x 4 = 96mV for 48V system.

At 25C temp.compensation should be zero. So the absorption voltage without compensation should be 57,6V at 25C.

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