First steps, and some questions...


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cotje

New member
Joined
Dec 1, 2021
Messages
4
Hi all, just new to this forum that I found during my search for solutions to create my own accuwall. Hope you can help me confirm and/or guide to what I know now. Let me start by explaining what I have running atm:
- 3-phase grid power from provider with P1-mon attached to the Smart-meter
- 30x 285W solar panels and SolarEdge 8K 3-phase inverter (4 yr running, 8,5 MWh/yr)
- 8x 380W solar panels and SolarEdge 3K 3-phase inverter (installed recently)
- Main consumers: 75kW electric car and 11kW Wallbox, 1kW homelab running 7x24, average monthly consumption 800kWh (1200kWh with car charging)

My aim is to install a 3-phase battery/charge/inverter system. Inspired by 'Meine Energiewende'/Jens? I see two main options (per phase):
1. 4x Tesla 2S modules with simpBMS and Victron Multiplus II 24/5000
2. 8x LPF 280Ah batteries with Batrium Blockmon M8 modules and Victron II 24/5000 units

As far as I understand now the LPF/LifePo4 options is newer and cheaper (safer?). Not sure if/why I should go for a 24V or 48V system?!

My questions are mainly about the features of the MultiPlus charge/inverter (that will be connected to the grid/provider):
- Will the MP control the overcurrent from the solar inverters to charge the batteries automatically?
- For three-phase function, do I need to configure each MP to make them aware of each other?
- Does the MP automatically deliver battery power in case I need to charge my car?
- Do I need other (Victron) devices to complete the setup?

I'm hoping the Victron MP is smart enough to charge batteries while on solar power and deliver battery power when needed, thereby eliminating as much as need for grid-power. And, of course, deliver power when grid-power fails ;-)

Thanks in advance!
 

Redpacket

Active member
Joined
Feb 28, 2018
Messages
1,392
At those power levels, you should go straight for 48V to avoid losses.
Either battery type is fine, but the LFPs will probably last longer & like you say are more stable chemistry.
Don't know about the MP functionality, sorry.
Yes, for 3 phase, the inverters are linked & configured to operate as 3 phase
I would add a Victron BMV-712(s) as a separate SoC/voltage monitor.
I understand the Victron Multiplus will power share to a load, but unless they've changed from the one I have (might have updated this!) I don't think they dynamically & interactively manage a battery like you'll need. I have to manually switch mine to charging mode (inverter section is off).
You need AC coupled battery inverter/charger function with your system ie like a Telstra PowerWall does.
 

cotje

New member
Joined
Dec 1, 2021
Messages
4
Thanks!
Just was caught up in this thread about grid-tie functions and what the MPII does in that aspect. If I understood correctly the MPII does exactly what I hope for.

 

Zwy

New member
Joined
Nov 29, 2021
Messages
4
Hi all, just new to this forum that I found during my search for solutions to create my own accuwall. Hope you can help me confirm and/or guide to what I know now. Let me start by explaining what I have running atm:
- 3-phase grid power from provider with P1-mon attached to the Smart-meter
- 30x 285W solar panels and SolarEdge 8K 3-phase inverter (4 yr running, 8,5 MWh/yr)
- 8x 380W solar panels and SolarEdge 3K 3-phase inverter (installed recently)
- Main consumers: 75kW electric car and 11kW Wallbox, 1kW homelab running 7x24, average monthly consumption 800kWh (1200kWh with car charging)

My aim is to install a 3-phase battery/charge/inverter system. Inspired by 'Meine Energiewende'/Jens? I see two main options (per phase):
1. 4x Tesla 2S modules with simpBMS and Victron Multiplus II 24/5000
2. 8x LPF 280Ah batteries with Batrium Blockmon M8 modules and Victron II 24/5000 units

You don't need the Blockmon's anymore. You can use a Watchmon CORE with K9's. https://www.batrium.com/collections/kits/products/watchmon-core-k9

Here is a video from Lithium Solar about the CORE and K9's.
View: https://youtu.be/m0Z25-jqLrs


Much easier install, lower price and does everything you need to do. If you add another 24V bank, you can just add another K9.

If you are wanting a 5Kw inverter, I'd opt for 48V which the Watchmon CORE and K9 will also do. Want to add another 48V bank? Just add another K9 or you can go 2P16S with just one K9. I prefer 2 K9's and two 16S banks in parallel just to keep amps down per bank.
As far as I understand now the LPF/LifePo4 options is newer and cheaper (safer?). Not sure if/why I should go for a 24V or 48V system?!

48V is the way to go on larger systems. I'm currently building two 48V LFP banks with prismatic cells, Batrium Watchmon CORE and 2 K9's. Less amps per bank and wires can be downsized.
 
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