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sesshoumaru avatar image
sesshoumaru asked

Limits of AC an DC coupled PV

Hi


I have a three phase system with Quattro 48|5000's. At the moment its fed by a Fronius Symo 6 on AC-1-out, deliverying 6kVA on full power. I am planning to add about 10kVA solar power on DC side with a MPPT RS450/200. And potentially also a Hoymiles HMS-2000 on, probably, L1 (again AC-1-out).


My queustion is about the limits of the system.
Assume there is full power sun and we get 8kVA from AC-coupled solar (which should be fine with 1:1 rule, 8 < 15). What happens if the DC side power its full 10kVA towards the Quattros? That would mean 10kVA from DC and 8kVA from AC, which is well above the systems 15kVA? Would the GX tell the DC MPPT to go down, preveting the system from overload? Or how are such scenarios working?


Thanks in advance :)

MultiPlus Quattro Inverter Chargercerbo gxmppt rs
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2 Answers
rikhf avatar image
rikhf answered ·

The 450/200 will send its power to the battery. The quattros have nothing to do with that so don't worry.

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sesshoumaru avatar image sesshoumaru commented ·
Does that mean if the battery is at 100% no power will go through the Quattros to feed back into the grid?
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Dave Rae avatar image
Dave Rae answered ·

Hello,

Your GX_device directly controls the MPPT charge controllers via the VE_direct connection, and will instantly throttle them back while increasing the AC frequency to reduce the output of the AC coupled inverter...

So yes your assumption is correct...

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sesshoumaru avatar image sesshoumaru commented ·
Guess this is why the 1:1 rule is important for AC-coupled PV as in this case the inverters cannot increase the frequency and have to endure.
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