Hi

 

I might be wrong but it looks like the default behavior of victron inverters which has 2 AC inputs is to switch from AC 2 (solar or generator) to AC 1 (eskom) if AC 2 cannot deliver enough power.

 

So my question is, does victron have an inverter that pulls power from AC 2 and supplements power from AC 1 if AC 2 cannot deliver enough power?

 

Thanks

-G-

1 hour ago, gallderhen said:

I might be wrong but it looks like the default behavior of victron inverters which has 2 AC inputs is to switch from AC 2 (solar or generator) to AC 1 (eskom) if AC 2 cannot deliver enough power.

Not at all. For the Quattro inverters (those with two AC inputs), there is a simple priority. If both AC inputs have AC present, then it prioritises input 1 over input 2. Usually you would install your generator on AC-1, so that merely starting the generator is sufficient to switch to the generator (even if the grid is up), and stopping the generator sends it back to the grid (on AC-in-2).

If for whatever reason the inverter doesn't like the AC input (eg weak generator, not a good sine wave, etc), and there is AC on both inputs, then it may instead move on to AC-in-2.

It cannot mix power between the two AC inputs, because... well that is not how it works... the generator would have to be synced with the grid for that to even work. It's just two interlocked transfer switches...

Edited September 4, 20205 yr by plonkster

Thanks plonkster,

 

That's what I suspected.

Another question I have is, if looking at this diagram:

 

would power drawn always use as much power from the PV inverter, before drawing "the rest" from the multiplus if the draw exceeds the total amount the PV inverter can deliver?

 

-G-

14 minutes ago, gallderhen said:

would power drawn always use as much power from the PV inverter, before drawing "the rest" from the multiplus if the draw exceeds the total amount the PV inverter can deliver?

Yes.

In more detail, if it is running off-grid, then the Multi raises the frequency to throttle the PV-inverter, and it is regulated to the point where all the loads are powered and the battery is fully charged. If there isn't enough power, the frequency drops to 50Hz, the PV-inverter runs flat-out, and the remainder comes from the batteries.

If it is running grid-tied, and you are allowed to feed into the grid, then by definition the PV-inverter's generation is used first (the remainder charges batteries, and when that is done, the rest goes into the grid). When not feeding into the grid, then it become a bit more complex. Then at times (while ramping up, adjusting) the PV-inverter might be limited while some power comes from the batteries. Which is why it is better (even if you don't get paid for it) to feed the excess into the grid...

Thanks for the explanations 🙂

 

-G-

Hi Isaac,

when the Multiplus II is running grid tied ( no feed in ) and DC coupled, does the same apply to the MPPT , being limited while ramping up and some power coming from the batteries

20 minutes ago, Tariq said:

when the Multiplus II is running grid tied ( no feed in ) and DC coupled, does the same apply to the MPPT , being limited while ramping up and some power coming from the batteries

No, the mechanism is different. The MPPTs regulate on battery voltage and are a lot faster than the control loop that limits PV-inverters in an AC-coupled setup.

On 2020/09/04 at 5:14 PM, plonkster said:

The MPPTs regulate on battery voltage and are a lot faster than the control loop that limits PV-inverters in an AC-coupled setup.

I don't use Victron MPPT's, but I am considering them. If possible, can you quantify "a lot faster" into some practically expected times of DC vs AC coupled responses please?

6 hours ago, phil.g00 said:

a lot faster

The ESS control loop adjusts PV-inverters every 5 seconds, but MPPTs generally react in the 100ms bracket? 🙂

 

Edited September 6, 20205 yr by plonkster