Hello everyone, I have a system running properly with ESS. I’m now wondering if I even need ESS? A bit about my system and setup: 15 Kw of PV 30 kWh of BYD managed lithium batteries 15k quattro Cerbo MK2 Two 450/100 chargers - All loads are on AC out 1. AC out 2 can’t be used for technical reas…

[image] Fideri K: Are there flaws in my thinking? Constantly switching the relays isn’t great for lifespan of a system. Accepting mains takes time, depending on the grid code, it also has ramp times. You could use more grid doing this than the setpoint would. You seem to be trying to reinv…

[image] Nick: You could use more grid doing this than the setpoint would. I can see the point there. I hadn’t thought about that. I don’t see what the benefit of removing it and adding a more rudimentary control system would be. I was thinking of the ability to switch to passthrough when …

[image] Fideri K: I was thinking of the ability to switch to passthrough when loads are high. That isn’t easily done. You can switch to “charger only” which is effectively passthrough for loads but can charge the batteries.

I am doing just that but with the hardware of the Multi RS. I am using conditional AC-IN connection when the SOC is below 30% And I am also using connect AC-IN when the load is above about 80% of the inverter’s max output power and disconnect when load is below 50%. All this because you have such…

[image] Fideri K: Use programmable relay assistant with a high power relay (I have some such relays lying around) with 2 conditions: 1. Switch on grid when SOC is below 20% 2. Switch on grid when loads exceed 9200W for 1 minute There is a thread here. [image] Control…

Did I misunderstand something? Yes, I’m aiming to achieve exactly what you are doing with your system, albeit with different hardware. My transfer switch should be fine. It is the Quattro relays, such as the alarm relay, that I’m worried about. Since given my hardware I need such a relay to switch o…

Thanks for that. Time to experiment which I’m happy to do.

To add, it seems you can control AC out 2 without an external relay, but not AC out 1.

Maybe I am the one I don’t understand… Do you really want to bypass entirely the Quattro when >9kW, or it’s OK to use the Power Control/Assist functionality? I was talking about this… [1]

Do I even need ESS?

DIY

lxonline (LX) 16 August 2026 10:17 9

There is a thread here.

If you want zero grid charge maybe disable the internal charger on the inverter or use the one charge control assistant to be able to manipulate if you would like the option to do so at some point

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Do I even need ESS?

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