question

gyrex avatar image
gyrex asked

Simultaneous charging with a grid tied PV inverter & MPPT charger in parallel possible?

Page 40 of the Wiring Unlimited guide states:



Voltage sensing in an Energy Storage System (ESS) with DC Solar

In an ESS system with an MPPT the charger of the inverter/charger is disabled.
This is because the MPPT charges the battery and excess solar power is being fed back into the grid. This process is controlled by the CCGX. To make this work, the CCGX will set the MPPT at a higher DC voltage than the inverter/charger’s DC voltage.


Assume there's a grid tied PV inverter connected to a MultiPlus II on AC-Out-1 with an MPPT charge controller connected to the same MultiPlus II. We'll use this diagram as an example:

Does this mean that the power output from the grid tied PV inverter will not be used to charge the batteries and only the power output from the MPPT charge controller will be used to charge the batteries?

As far as I can tell, the ESS guide doesn't make any mention of this inability to provide simultaneous charging from MPPT's and other energy producing units connected to the MultiPlus, in fact, it seems to imply that this is possible?

Multiplus-IIMPPT Controllersbattery chargingESS
fronius-victron-8.png (90.7 KiB)
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
Riaan Barkhuizen avatar image
Riaan Barkhuizen answered ·

Hi @gyrex


Don't dispair, the Fronius inverters will still charge the batteries even together with the MPPT.


Best Regards

Riaan

4 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

gyrex avatar image gyrex commented ·

Thanks Riaan, I thought this was the case and it seems to be implied on the manuals for the MultiPlus II and ESS.

Can someone from Victron confirm if this is the case and if an amendment needs to be made in the Wiring Unlimited guide to reflect this?

@Guy Stewart (Victron Community Manager)

@Margreet Leeftink (Victron Energy Staff)

@Daniël Boekel (Victron Energy Staff) - are you able to confirm if this answer is correct and if there's an issue with the statement made in the Wiring Unlimited guide?

0 Likes 0 ·
Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ gyrex commented ·

@gyrex

Please do not @mention moderators unless it is specific. There is some guidance on this in the community guidelines.

Riaans answer is correct.

0 Likes 0 ·
gyrex avatar image gyrex Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

I'm asking for clarification because there appears to be a glaring contradiction in the information on page 40 in the Wiring Unlimited guide and what's stated here. Surely this is important?

"In an ESS system with an MPPT the charger of the inverter/charger is disabled."

As someone who's seeking to invest a lot of money in your equipment, one would think this forum should be able to provide some kind of pre-sales mechanism to check the capability and features of your equipment. When there's perceived contradictions in your manuals, questions such as this are hardly surprising and one would think it's in the moderator's best interests to ensure that these contradictions are fixed?

0 Likes 0 ·
Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ gyrex commented ·

Hi @gyrex

Thanks for that remark, we're looking in to how to make this more clear.

In short:

Without ESS assistant, a Multi / Quattro inverter charges from the grid as soon as grid is available, in ESS mode, the standard function is: it only charges when there is an excess of power coming from it's output (from PV inverters)

0 Likes 0 ·
Margreet Leeftink (Victron Energy Staff) avatar image
Margreet Leeftink (Victron Energy Staff) answered ·

Yes, AC coupled inverters can charge the battery.

The piece of text you quoted only applies if there is DC PV in the system and only when excess energy is being fed into the public grid.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.