EMS charge/discharge settings

We have had an EMS installed with our dual AC3.0 plant system - all working well to date..
The system is set up, as per comments here about ensuring the timed charge and planned discharge times dont overlap…. So between 00:00 and 05:00 we have a charge time and the 05:01 to 23:59 a discharge time slot. All good so far….
As we get more PV into the system I have wound the nightine charge % down and last night, the battery charge stayed above the threshold… Happy days I thought… we’re self sufficient… however as some might foresee, although the system didnt need charge - it disnt didnt discharge between midnight and 5, forcing the house load to be satisfied from the grid….🙁.

Havent tried but are we sure the charge and discharge time cant overlap?… ideally I dont need a planned discharge slot- allowing the batteries to discharge during the period when charge may be required… but when we were setting up, no timed discharge slot stopped the system discharging at all?

As it is generally working I am reluctant to start playing with settings as we had a job to get the system stable and working over several days and lots of GivE tech support…

With limited info on the EMS setup at the monent, any experiences of the set up appreciated?….

I was going to try and increase the discharge period to say 00:10 to 23:59 for example but that means there will be an overlap with the timed discharge period?…. And a 10 min period of grid charge (albeit it at low rate)…

Paul

pauldavies no timed discharge slot stopped the system discharging at all?

Have you got Eco mode turned on? If the battery didn't discharge to meet house load then it sounds like Eco mode was off. You normally shouldn't need a discharge time slot, just set charging to when you want to fill the battery and ensure Eco is turned on and the battery should discharge to meet house load or charge from solar during the day.

The discharge time slot is useful if you want to preserve the battery for specific times of day, e.g. on Flux you might charge overnight, let the house run on solar or grid import during the day, and the battery support the house during the evening peak. In that case a discharge slot from 16:00-19:00 ensures that the battery only discharges in the evening peak so you avoid the higher import rates.
For your scenario it doesn't sound like you need a discharge slot setting up

Thanks Geoffreycoan - that certainly is how I would expect things but we had so much of an issue when the discharge slot was not set with the battery not discharging at all… in the end GE support and a post on here talked about setting the discharge slot and ensure it didn’t overlap the charge time, we did that and it all burst into life and worked. Worried if I delete the slot we will go back to the zero discharge state?..!..

geoffreycoan EMS has no Eco mode. It has Timed Charge, Timed Discharge and Timed Export. They can overlap - Timed Charge has the highest priority, Export the lowest. Timed Discharge is in effect 'Eco mode'.

Slartibartfast EMS has no Eco mode. It has Timed Charge, Timed Discharge and Timed Export. They can overlap - Timed Charge has the highest priority, Export the lowest. Timed Discharge is in effect 'Eco mode'.

thanks, learn something new every day!

Wonder why the EMS has different modes from the underlying inverters, would have thought it would have made the EMS coding much simpler if it mirrored the EMS modes straight through to the underlying inverters. It sounds like the EMS has to now do translation of these different settings (and priorities) as to what it means for the inverters.

Also means that everything that programmatically controls the inverters has to understand these differences, ie. Axle GivBack, Intelligent Octopus Flux, My Energy Optimiser, Wonderwatt, GivTCP, etc
Seems short sighted. Doubtless there are reasons for it being so, but strange

Slartibartfast

Thanks and very helpful.

I am going to overlap charge and discharge times and see what happens.

P

Hi,

Ok. Adjusted timed discharge settings and overlapped the timed charge settings….

During the timed charge settings the grid took the load again, not the batreries - which is not what I want - and as the batteries were above charge % threshold there was no charge added - correctly as I see it..

So I deleted the timed discharge slot to see if it will operate without a timed discharge as suggested and the system went immediately back to fulfilling the house load from grid with no battery discharge…. So I have recreated a timed slot of 00:00-23:39 and the batteries are now discharging the house load. ?

I suspect when we get to the timed charge period tonight, the batteries will stop discharging?…

There is an iption to turn off the timed discharge but if you try that and save the settings it fails to write/latch so have never been able to see how the system behaves with this toggled off?…. Anyone else seen this or know if this is a current issue or bug?
Paul

pauldavies During the timed charge settings the grid took the load again, not the batreries - which is not what I want - and as the batteries were above charge % threshold there was no charge added - correctly as I see it..

If I understand what you are saying, it seems like it might be operating correctly.

You set discharge for 00:10 to 23:59 so if the battery is doing nothing else it will discharge during this time period

You then set charge for 00:00 to 05:00 with target 80%

Assuming the EMS works similar to the other batteries, during this time period the battery will be in charge mode and will not discharge.

If the battery is below 80% then it will charge from the to that limit and hold at that limit. Any house load will be taken from the grid because the battery is in charge mode but can’t charge any more as you have set a limit to the charging.

If the battery is above 80% then it doesn’t need to charge, but its in charge mode and will hold with the battery above the limit until the end of the charge period. Any house load comes from the grid.

It sounds like you need to reduce your charge period duration if you want the battery to start releasing charge to the house earlier than 5am

geoffreycoan

Hi. Thanks for your description and yes I agree, if the logic of setting the timed charge inhibits any discharge. I was thinking they would be independent

I was rather hoping that now we are at a point where the PV generation is putting enough energy into the batteries for us to be self sufficient and the overnight load can and would be satisfied by only the batteries, I would see no grid import….. but with the logic as you have explained, looks like I need to disable the timed charge period and rely solely on PV. The downside to this is that it needs manual monitoring to ensure if you do drop below a battery% threshold you will want a timed charge from the grid to kick in….? With an EV sometimes taking a night charge that drains batteries - having the timed charge to ensure the min % is maintained is useful…. another thing to sort!

Does that sound right?…

I m having problems getting a good strategy setup as well. I want to use PV energy and and excess PV to go directly to the battery instead of it going to the grid. Eco mode should do this.
Also want to have enough battery charge to let the house run on battery during the Octopus peak tariff between 16:00 and 19:00 and preferably till 22:00 when cheap period kicks in.
If I setup a charge cycle between 13:00 and 16:00 with a AC Max SOC % specified for when there are no sunny days to charge the battery. Now the issue is that when the MAX SOC is reached the excess PV is not stored in the battery but goes to the grid. This is not what I expected. Contacted GivEnergy, their response was, this is what most customers want.Not sure about this. I would think that when ECO mode is on, EV excess should always got to the battery until the mac SOC is reached in the battery specification. Any thoughts about this please.

pauldavies but with the logic as you have explained, looks like I need to disable the timed charge period and rely solely on PV. ... With an EV sometimes taking a night charge that drains batteries - having the timed charge to ensure the min % is maintained is useful…. another thing to sort!

If you are on a tariff where the overnight import costs less than daytime export, then it makes financial sense (and is logistically trivial) to continue to charge from grid overnight, and simply export excess solar during the day.

It's easy to justify this from a green perspective - you are shifting your neighbours' daytime usage to your nighttime usage.

duncanstrachan11 Also want to have enough battery charge to let the house run on battery during the Octopus peak tariff between 16:00 and 19:00 and preferably till 22:00 when cheap period kicks in.

Are you on the Cosy tariff ? Assuming your export rate is 15p, then it is more or less cost-neutral to just charge from the grid during cheap rate, and export excess solar.

You could possibly used tiered charging: from 13:00 to 14:00 with a max SoC of, say, 50%, then 14:00 to 15:00 for 60% and 15:00 to 16:00 for 75%. Then if it's a sunny day, the PV will raise the SoC above those levels anyway. Doing it as a single charging period means you're likely to get to 75% during the first hour. (The limit should apply only to AC charging - solar is allowed to go beyond that.)

This does have the downside that you will use grid even if battery level is well above the target SoC, but that needn't be a bad thing - gives you some excess energy to export back to the grid later in the day, to balance the cost.

(Is this related to EMS ?)

DD

Then if it's a sunny day, the PV will raise the SoC above those levels anyway.
That is the point, it doesn't as during the time the AC charge cycle is active, no PV excess is charged when the SoC is reached in that period. Would be a lot simpler when ECO is switched on all PV excess would be used to charge the battery .
I tried the tiered approach, it does not work.
Yes we are on Cosy tariff, no export energy payments.

duncanstrachan11 Oh... sorry, yes, you're right. My battery is on 89%. Just tried an experiment with an ac charge slot until 4pm, limit 70%, and eco on, and, as you say, the battery is idle and the solar is all being exported.

In that case, you may need to use an external agent to configure conditional charging slots: https://community.givenergy.cloud/d/5221-app-for-setting-multiple-charge-periods