Asking for feedback on system plan

DIY
1

My situation: We have a mostly reliable grid and no solar capacity. Mostly reliable because we get one or two winter power outages that have gone up to 10 days each year. No solar capacity because we are surrounded by tall cedar trees. Also, the on-peak rate is a bit expensive compared to the off-peak and mid-peak rates.

My goal: Time shift my power so I am not using the grid during the on-peak rates. Be able to keep the house livable during the winter outages.

My plan (diagram at end of message): Split my main panel into three panels: grid-only, on-peak, and essential. The on-peak and essential panels will each be connected to ACout2 on separate MultiPlus II units. The grid-only panel has the loads that do not need to be backed up. The on-peak panel has things we do without during long outages (lights, dishwasher, microwave, …). The essential panel has the things we need in the winter (furnace, water heater, pipe heater, battery heater, …). The battery is large enough to run the loads in the essential panel for two weeks. It is also large enough to run the on-peak panel for a day.

From what I have read in the documentation and in other community posts, the MultiPlus II units can do scheduled charging - but there does not seem to be a concept of scheduled discharging. (Please let me know if I am wrong on this.)

In order to do scheduled discharging I will have to use node.red to disconnect a MultiPlus II unit from its ACin during on-peak time. (Again, please let me know if I am wrong on this.)

So, does this sound/look like the right way to do this?

power notes
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2

There is no “scheduled Discharging”, that is right. But when running in ESS Mode, the system will always favour solar usage over battery discharge over grid usage.

So, If you setup your system to act as ESS, set a charging schedule to the “cheap times”, everything will happen as you would like to have it:

  • Battery is loaded, when grid is cheap.
  • Every other time, loads will be powered from the battery.

In general, which would be helpfull for your situation, you can also specify that the system should only use downto 50% (or whatever value) battery, as long as grid is present. So, you could set the desired amount that should be available in case of an unexpected grid loss.

Victron is currently also experimenting with DESS (Dynamic ESS) that even takes grid prices into account to automatically reschedule charging - but at the moment unfortunately “experimenting” is the only word to describe this feature :face_with_peeking_eye:

As of your plans:
Splitting the Panels into regular Loads (turned off during grid loss) and emergency loads (kept online during grid loss) is fine, but wouldn’t over engineer it here.

The on-peak panel is also obsolete, you cannot turn off the AC-Out of a single multiplus. When you hook them up, either parallel or on split-phase, they act as “one” inverter. You can just turn off AC-Out for both units or none.

Running them in an isolated way would require each multiplus to have it’s own battery, cerbo, solar, etc.

However, nothing would stop you from using any remote-controllable switches, smartplugs, etc. to enable or disable loads wired to either the regular or emergency panel.

3

In the event of a grid failure, ACout2 is automatically switched off, the inverter will only feed ACout1. So you could have ACout2 feed your on-peak loads while ACout1 feeds the essential loads.

In the event of sheduled discharging, you dont physically switch anything, only tell the inverter to feed-out/in 0W. Pretty sure thats an ESS feature, but ESS is not my strong side. Im also not sure about two grid meters. So to me, one inverter, or running two in parallel would be enough, no need to split more

You could also use two inverters in a split-phase config while still using their ACout2 for the on-peak loads and ACout1 for the essential loads

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Thanks - I had my ACout1/2 swapped. I originally went with the two inverter design because of power requirements - with a single 48/5000/120 I would be a bit past the upper edge if most things were on at the same time - it should not happen but extended family and their kids visit and unexpected things will happen. Too bad a 48/8000/120 is not available.

I had hoped that with node.red I could tell one inverter to do one thing and the other to do another thing if they were used as separate single-phase inverters and not setup to be split-phase.

Time for some more reading and searching.