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dallas-cass avatar image
dallas-cass asked

Quattro 48/15000 AC and DC coupled systems

We are busy with multiple sites whereby we need between 90 and 180 KVA inverting Power.

We are using a combination of Fronius Symo inverters and 250/100 VE Can MPPT's.

My question is simple: what is the most optimal ratio of AC coupled vs DC coupled to the Quattro's? I know the 1:1 ratio does not apply to Q15's.

For example: is it better to install 2 x Symo 15's with 3 x Q15's, as a balance, with 5 x 250/100's? these systems are completely offgrid, and have generators as alternate supply.



AC PV Coupling
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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Dallas Cass

out of curiosity: where did you read that the 1:1 rule does not apply? (I don't know of that, but I don't know everything ;)

The actual ratio between DC / AC coupled PV is something for experienced system designers to say, please refer to your Distributor or Victron Sales Agent for that.
It depends a lot on the amount of direct use vs night-time use, etc. (plus of course the 1:1 rule, the size / type of batteries, etc. etc.)

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dallas-cass avatar image dallas-cass commented ·

Hi Daniel

Well we have experienced that 10 kWp of PV on AC coupled systems is the maximum suited to the Q15.

I agree, we install as much on the AC Coupled side if there is a high daytime load.

So :

90 KVA Inverting - 50-60 kWp AC coupled

135 KVA Inverting = 75 - 90 kWp AC Coupled

180 KVA Inverting = 100-120 kWp AC Coupled

Then the balance of the PV on the DC bus, using 250/100's.


Thanks


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