Does The Multiplus Supply The loads From The batts ..The SCC..or Both.?

[JRH]

I read this topic once here in the forum ….but forgot the answer…

Let’s assume the panels are producing 3000 watts , and there is no load at all on the system.
In this case all the power should be going to the battery’s to be stored If there is room In the bank.

For some reason I decide to turn on the multi+ and a load that requires 1500 watts and the inverter starts to invert DC power to AC power and supplys that load.

The panels are still producing 3000 watts and the single load is drawing 1500 watts and is doing its thing.. …( For this example ignore the small power draw of the Victron).

Question: Is the 1500 watts ( of the 3000 supplied ) being used for AC power ,coming from the batteries AFTER it is stored in the batteries and then drawn and converted by the multi + to AC as needed by the load …?

OR is the 1500w ( of the 3000 supplied ) being supplied to the multi+ and going to the load First , and the other 1500 is being stored in the batteries… ?

Furthermore , If I turned on two loads of 1500 watts each would it all go to the load and none to the batteries OR does all goes to the batteries FIRST and then be pulled back out and sent to the inverter and then to the loads.

There is a reason for this question ,but I’m trying not to complicate things …

Thx, J

 

[Mattb4]

First off loads pull power from a supply. Supplies do not push power. So when your panels have no load they are not producing anything other than voltage. Batteries are a load when not fully charged.

In a SCC setup the panels are loaded by the SCC as it creates a DC common bus connected to your batteries and inverter. Batteries charge when the voltage potential on the common bus is higher than their internal voltage. Loads being supplied by the inverter take precedence because they have no internal voltage to overcome. As loads are placed on the DC common bus it reacts by increasing demand on the SCC and from that to the panels. If the panels can not supply all the load the DC bus voltage drops to the point that the batteries internal voltage is enough that it starts to discharge and picks up the difference.

 

[RCinFLA]

You cannot have 3000 watt sourced with only 1500 watts consumed.

All PV generated power must have a place to go,

Your choices are:
AC and/or DC loads
Battery charging
Push to grid

If load on SCC is less than available PV power the SCC will allow array voltage to rise and bleed illumination generated current back into panels cells' inherent diode where the power is dissipated. SCC power output will only be what is consumed.

At maximum power point on silicon PV panels about 5% of illumination current is bled back into PV cells. This provides the best V x I product from panels. ( I_mp is about 95% of I_sc, and Vmp is about 85% of Voc )

 

[sunshine_eggo]

Question: Is the 1500 watts ( of the 3000 supplied ) being used for AC power ,coming from the batteries AFTER it is stored in the batteries and then drawn and converted by the multi + to AC as needed by the load …?

No.

OR is the 1500w ( of the 3000 supplied ) being supplied to the multi+ and going to the load First , and the other 1500 is being stored in the batteries… ?

No.

Furthermore , If I turned on two loads of 1500 watts each would it all go to the load and none to the batteries OR does all goes to the batteries FIRST and then be pulled back out and sent to the inverter and then to the loads.

No.

All answers were "no" because you placed an order on things.

There is a reason for this question ,but I’m trying not to complicate things …

Thx, J

Current only flows one direction, in or out of batteries. Consider a simplified system:

MPPT to battery terminals.
Inverter to battery terminals.

The battery is a load to the charger at the battery terminals.
The inverter is a load to the charger or battery at the battery terminals.

If 3000W is available, battery can accept 1500W, and 1500W is needed for loads, 1500W of the charger's output goes directly from the MPPT to the loads through, and 1500W goes into the battery. There's no "first" or "after." It's simultaneous.

 

[JRH]

First off loads pull power from a supply. Supplies do not push power. So when your panels have no load they are not producing anything other than voltage. Batteries are a load when not fully charged.

In a SCC setup the panels are loaded by the SCC as it creates a DC common bus connected to your batteries and inverter. Batteries charge when the voltage potential on the common bus is higher than their internal voltage. Loads being supplied by the inverter take precedence because they have no internal voltage to overcome. As loads are placed on the DC common bus it reacts by increasing demand on the SCC and from that to the panels. If the panels can not supply all the load the DC bus voltage drops to the point that the batteries internal voltage is enough that it starts to discharge and picks up the difference.

I totally get it.. that’s pretty much what I have observed and thought would happen…I should have asked the question better…Thank You..

 

[JRH]

If 3000W is available, battery can accept 1500W, and 1500W is needed for loads, 1500W of the charger's output goes directly from the MPPT to the loads through, and 1500W goes into the battery. There's no "first" or "after." It's simultaneous.

This is what I was trying to ask …simultaneous …yess….. this is what I have thought happens …I didnt articulate my question as good as you answered it…

so with all this said…, if I add a lot more panels to my system this spring with the intent being to have enough PV output to power all the normal loads during the daytime + keep the battery’s more or less full by the end of the day ,the loads will take precedence all day while “simultaneously “ sending any extra power to the batts if they “need” charging …


in effect, get all the heavy lifting done while the sun is available ,and when the sun goes down trim back the loads at night and runn off full batts , repeat the next day If possible.

that is what I’m aiming for this year…I had no where near enough panel power to do it this way this summer…
J.

 

[JRH]

You cannot have 3000 watt sourced with only 1500 watts consumed.

All PV generated power must have a place to go,

Your choices are:
AC and/or DC loads
Battery charging
Push to grid

If load on SCC is less than available PV power the SCC will allow array voltage to rise and bleed illumination generated current back into panels cells' inherent diode where the power is dissipated. SCC power output will only be what is consumed.

At maximum power point on silicon PV panels about 5% of illumination current is bled back into PV cells. This provides the best V x I product from panels. ( I_mp is about 95% of I_sc, and Vmp is about 85% of Voc )

I totally get your first couple of parts and options you offer… and I Thank you for taking the time to help…

but the bleeding and illumination part has me wanting to reach for a beer far too early in the day…
haaaa, I mean that in the best of spirits…
Thanks guy… J.