Squeezing all my charging into 4hr Octopus Go window

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eamonno asked Jan 7, '23

Squeezing all my charging into 4hr Octopus Go window

Good morning.

My new 48/5000 is now fully operational, and charging 4 x Pylontech 3000c to 100% each night, within the 4hr window.

I also have an EV, with dumb charger. It occurs to me that timing might be important when I charge both at the same time.

My ESS timer is set to start start and end charging within the window

Question: if my battery reaches 100% early, will the EV charger switch to charge from the battery, thereby depleting it? Or does the ESS remain in charge-only mode for the full during of its programmed charge window?

Thanks again!

Multiplus-II cerbo gx battery charging Pylontech

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Answer 1 · 2023-01-07T09:23:07Z

nickdb answered · Jan 07, 2023 at 09:23 AM

Question: if my battery reaches 100% early, will the EV charger switch to charge from the battery, thereby depleting it? Or does the ESS remain in charge-only mode for the full during of its programmed charge window?

It will remain in charging mode and not permit battery discharge until the schedule completes.

Personally I would use node red to change ESS to "keep charged" at the start of your window, and when SOC hits 100% switch back to self-consumption.

If you had a smarter EV charger that you could integrate with node red, then you could control that as well.

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eamonno commented · Jan 07, 2023 at 02:24 PM

At a granula level: if Keep Charged is ticked, and it switches to self-consumption at 100%, let’s say it discharges 5%….will node red persuade it to top up, and send the eV back to the grid? (Until 100% is once again achieved?)

One could get dizzy with this stuff :-)

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Answer 2 · 2023-01-07T10:39:40Z

johnone answered · Jan 07, 2023 at 10:39 AM

It's a good question. I too have a recently installed similar system and the first question is - what happens when the battery reaches the desired SOC state during a scheduled charge period. Be good if this scenario was more clearly explained in the manuals.

re using node red and "when SOC hits 100% switch back to self-consumption" - isn't that what the OP doesn't want? Given PV is not mentioned, surely the OP wants to make maximum use of the cheap rate period - i.e ideally, at the end of the period both EV and ESS batteries are fully charged? Therefore, don't switch to 'self-consumption' until after the cheap rate period ends.

Personally, I'm tending to think that node red is very often overkill, that ESS works really well (though the configuration is fiddly) especially for scheduled charging. See if ESS will do what you want first, then look for another control system if needed. When the sun starts to shine (in the UK Spring) and ESS config becomes more complicated, I'll be looking to use python to access ModBusTCP, to integrate with other house automation systems.

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nickdb ♦♦ commented · Jan 07, 2023 at 10:59 AM

If I refer to the manual: "If the target state of charge is reached, and it is still within the period of time set, the battery will stop charging but will not discharge (unless there is grid outage). This optimises battery cycling and still allows room in the battery for PV charging."

And this is indeed how it works.

The system will only revert to consumption at the end of the schedule, something some users would prefer not to happen to reduce grid usage.

Unfortunately ESS does not work that way, but node red can enable this via automation.

For the OP he does not want to discharge the batteries, so the schedule works fine, but needs to coordinate EV charging.

Within the configured AC input limit and schedule window, he can charge both batteries and the EV.

The moment you would like more sophisticated coordination it would require a smarter EV charger, or for you to get creative with node red.

ESS works brilliantly for what it was designed for, though now there are more complicated use cases, to cater for persistent blackouts and dynamic grid tarrifs.

Dev work is well underway to enhance ESS for the latter, though many have already accomplished it using node red.

For most users vanilla ESS is sufficient.

I have done a fair amount of dev work with node red to automate for my purposes and it is a very powerful tool if you can clearly define the logic you want it to enable.

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johnone nickdb ♦♦ commented · Jan 07, 2023 at 12:27 PM

re the manuals, the problem is they have clearly grown over time and have become difficult to navigate. Yes, it's all in there, but you have to wade through lots and lots of irrelevant data and instructions to get to the most common usage scenarios.

As others have mentioned on here, a different way of organising the manuals is by use case, and making the most common use cases the most prominent. Clearly, there's a big increase in one type of usage - time shifted ESS, given energy costs and availability of batteries that sit in the house. Proactive customer service could prioritise that scenario and, quickly and easily gather together all the relevant sections from the manuals. I know everyone will say they are busy - but they'd be less busy if life was made easier for users. I guess that the balance for deciding what to prioritise?

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Answer 3 · 2023-01-07T13:20:41Z

dmsims answered · Jan 07, 2023 at 01:20 PM

How does the Stop on SOC in the schedule affect this ? (and why is the limit 95%??)

ess-schedule-stop-on-soc.png (15.9 KiB)

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nickdb ♦♦ commented · Jan 07, 2023 at 01:24 PM

You can set the stop on SOC, this is the percentage where it will stop charging during the schedule. Loads will continue to be serviced from grid until the schedule completes.

The max is 95%, if you uncheck this option it will charge to full.

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johnone commented · Jan 07, 2023 at 07:48 PM

Questions most people seem to ask, including me - because it's not clearly stated in the manuals and it's a crucial part of the ESS set-up.

1. the 'stop' in 'stop on SOC' seems to refer to charging - i.e. not 'stop' the scheduled charge (which it could reasonably mean), but do stop charging when the 'SOC limit' is reached. An example where it makes perfect sense to people designing the system but not necessarily to users.

2. the 'SOC limit' can be altered - i.e. the down arrow in the bottom left corner is used to denote 'click to change' (something like that). In the UK, as PV becomes available (in the Spring) setting the SOC limit will become an important part of enabling self-consumption - i.e. charge the battery in the cheap period to a lower SOC as more PV becomes available.

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Answer 4 · 2023-01-07T14:18:47Z

eamonno answered · Jan 07, 2023 at 02:18 PM

Thank you all for your responses. I’m a voracious manual-reader: I’ve read them all, but trying to remember just where I read something by is not always easy - a common-use index would be useful indeed.

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