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limit eddi to battery max

• 17-07-2022 1:43am
Registered Users Posts: 2,682 ✭✭✭

I want to limit the eddi to draw in the morning to the battery only and not pull from grid.

I have a 6kw inverter and 5kw dyness battery. I think at max battery output it can send 2.5Kw. My battery this time of year rides thru the night and has enough juice to heat/boost the water in the morning.

When I have morning sun, it covers the extra draw from boost... but when it's grey It exceeds the battery output and draws from grid... about 1kw.

I'm thinking I need to set supply grid device limit? Correct? 12A would that do what I need?

• Registered Users Posts: 2,682 ✭✭✭

Answering my own test, check my work. Not setting anything, the eddi and house load hits 3.252 kW. Last night changing "grid device limit" to 12A (max is 16A) I ended up with a total draw of 3.076 kW during morning boost.

My battery will do 2.4kW max output so I need to go to 9kW on the eddi. Hopefully then I have zero grid draw tomorrow.

The math: divided 3.076 by 12A = .256

Divide 2.4kW by .256 = 9.375A

• Registered Users Posts: 2,682 ✭✭✭

• Registered Users Posts: 2,224 ✭✭✭

power (watts) = volts x amps

So if you want say 2400 watts limit that would be

2400 = 230v x amps.

Ergo your amps for this would be 10.43amps (assuming you have 230 voltage) Course you also have the house load (outside of the eddi), so your 9A would seem about right.

• Registered Users Posts: 5,744 ✭✭✭

Your best option is to get into automation

You can use the MyEnergi API with a simple url to start or stop the Eddi (Zappi can be controlled too). So in Node-Red or Home Assistant, if you can read the battery SOC from the Inverter or Battery, and read the generation level, then you can tell the Eddi what you want it to do ..... Automatically!!!

You could then go further and read the weather for the following day and boost from grid on night rate if the day was looking crap

• Moderators, Science, Health & Environment Moderators Posts: 4,562 Mod ✭✭✭✭

But you can't set the voltage limits on the eddi with automation, so setting a hard cap w/ the amps is the only workaround that can be achieved w/o MyEnergi changing their firmware

• Registered Users Posts: 5,744 ✭✭✭

Not sure what you mean about wanting to change the voltage.

As I said, you trigger boost based on the battery SOC and stop it when the SOC reaches a certain level, or continue if generation is above xxx watts (or that sort of thing)

• Moderators, Education Moderators, Home & Garden Moderators Posts: 7,826 Mod ✭✭✭✭

Read @yankinlk's post again. His battery cannot supply sufficient power his immersion on boost, hence the grid limits.

@yankinlk: that solution will work until you add a Zappi and need it to charge at any reasonable speed 🙂

Does the Grid limit also the Eddi output to 9A if using surplus solar? Or can that use the full 13A?

• Registered Users Posts: 186 ✭✭

@yankinlk , assuming your goal is to get hot water earlier in the morning, perhaps there is a different approach you could take. Why not prioritise the Eddi over the Battery in the morning, so all generation (minus house/base load) will go to the Eddi instead of battery.

I too have a 6kw inverter (Solis Hybrid) and a 5kwh battery (currently).

At just 5kwh, is there realistically a lot of spare capacity in the battery in the morning, even on these sunny days? In my case, it dips to about 50% these nights before morning generation starts again (and I have a very low base load). That leaves just 1.5kwh buffer before you're down to 20%, which is "empty" for a lot of setups. 1.5kwh isn't that much of a buffer, and personally I like to keep some buffer in the battery so kettle boils/other use won't deplete it and then I'm importing. So, the case of boosting from battery in the morning doesn't provide lot of value, for my usage patterns at least.

If you're charging the battery on night rate (2am-5am EV plan, for example), then its better "charge" the battery at 0A, and boost the Eddi from grid at that time. (This can be done via automation too. I do it when the day's solar forecast is miserable / below certain threshold. It puts 2kwh in from 4:20AM to 5:00AM). In summer, this isn't kicking in, but come winter it will happen regularly.

So, using random values for illustration, you could have some basic automation that:

• stops the battery from charging while SOC greater than 50% in the morning
• this means that all excess will be "exported", which means that Eddi will automatically kick in an consume it
• if SOC goes below 40% SOC, then flip back to normal battery charge mode (to preserve/build up a buffer). Note: The SOC will only go down if you have some appliance that consumes more than generation in this mode. E.g. boil kettle/dishwasher. If the house is still asleep at this time, the SOC won't go down.
• Battery will charge when you flip the mode back at 40%, and once it reaches 50% again it can go to prioritise export again
• you can disable this mode changing when Eddi reports "Max temp reached", or you you've put 2 or 3kwh into the immersion. The myenergi API gives all these values (I use a modified ha-myenergi in HA)

As you've got a 6kw inverter, I'm assuming you've got a large array, so our setups are possibly quite similar.

I've been doing this for a few months, and it works vey well. Water is hot an hour or 2 earlier each day compared to just letting battery fill first. I also find the Eddi to be much better at adapting to changes in load/generation than the Inverter is, so get less import due to load fluctuations using this method compared to boosting.

Post edited by connesha on

• Registered Users Posts: 2,682 ✭✭✭

First off - many thanks to ALL you replies. Lots of great ideas here. I will admit i will go the easiest route and am not currently using automation, or a zappi/electric car. My DHW tank is small enough that it doesnt take a huge boost to keep me in hot water... and the coffee maker is covered as well. :)

Here is my morning figures on 12A setting; you can see its causing some grid draw still:

And here is my setup now, with only 9A device limit (i think i could push to 10A) and no grid draw at all:

• Registered Users Posts: 2,682 ✭✭✭

I will see if i can test an empty water tank during a huge spike in power (later today maybe) to find out... but i think you might be right - it would be nice if i could ONLY limit the boost... but the settings on the Eddi are very basic.

Here is a different thought though... could i use "Supply Grid - Grid limit" - set it to zero and then i will get only juice from battery? I might have to swap it back in winter - but that might achieve what i want now - and still get the max input from solar....

• Registered Users Posts: 5,744 ✭✭✭

I think that "Supply Grid - Grid limit" is to set the max power that will go into the immersion element. It doesn't know or care or even decide as to what the source of this is.

To stop battery drain at ANY time, you would need to set it to charge to maybe 100% with zero watts. So it won't charge, but it won't discharge either.

Maybe it's worth to start looking, on the side, about dabbling with a Raspberry Pi. Rather than aimlessly turning one on, you now potentially have a project with a specific goal to aim for. It was absolutely be two steps forward and one backwards (or maybe even three at times !!!). We've all been there, but it's quite satisfying in the end.

Mind you, there's rarely an end point !!!

• Moderators, Science, Health & Environment Moderators Posts: 4,562 Mod ✭✭✭✭

My bad, I meant power, it's too hot here for using the right words. I would also like to be able to limit my eddi to 2.4kW (minus base load) when the sun is down but max when it's sunny, and it's not doable w/ the current settings.

• Registered Users Posts: 186 ✭✭

Since the myenergi API doesn't let you change those limit configs (AFAICT), you could do the automation on the Inverter side, instead of the Eddi.

For example, set a timed discharge from the battery at 50A for an hour. This'll "export" at a rate of approx 2.5kw. Your base load will take some of it, and the Eddi will pick up the rest.

This could be done relatively easily via automation; it's essentially the same as many do for timed (night rate) charge.

Depending on how much is in your battery at the time, you can have the automation set a different duration/current to make sure it doesn't deplete too much.

This way, you can set it up to run automatically so you never have to touch it after its setup. And it you want to do a full-power manual boost, that'll all still work as normal.

Using the Eddi variable-load capability, as opposed to boost, also has a bunch of advantages. Such as no longer needing to worry if someone turns on an appliance/kettle while you are "boosting", and hence going over your battery/inverter power rating. This way, the Eddi compensates (very quickly, and with no intervention needed)

• Moderators, Education Moderators, Home & Garden Moderators Posts: 7,826 Mod ✭✭✭✭

Very clever. I hadn't thought of that. You'd also need to monitor grid meter for export ( or poll the MyEnergi API) and disable once Eddi hits 'max temp reached' to stop the battery dumping to grid.

• Registered Users Posts: 186 ✭✭

👍️

For the other different interactions with myenergy, I currently monitor for an eddi_status of 'Max temp reached' or 'Unavailable', and a lower SOC cutoff level, to disable any non-default modes. (myenergi seems to go down for a few mins/hours every few weeks or so. Sometimes when its down the API returns 'Unavailable'). Yea, monitoring the real grid export would be a good idea on top of that.

• Registered Users Posts: 2,682 ✭✭✭

Some interesting ideas here thanks @connesha for this detailed write up.

I like your idea of automation - its a place I have yet to try my hand at - but may need to.

I dont have the same aversion to "draining the battery" as you seem to. I run it down to 12% and it literally empties this time of year only after the early morning boost to heat the water. The battery is always full again by 11am this time of year - and im always looking to slow down that charge by running Dishwasher or washer/dryer. I still export a decent amount everyday.

Come wintertime - i might revisit this - i do like the idea of boosting on night rate and avoiding the battery usage during that boost so i need to be clever with how i set it up. Im still on D/N meter so i dont have a 2am EV rate yet.

• Registered Users Posts: 5,744 ✭✭✭

Realistically, from when the clocks fall back until when they spring forward, you'll charge the batteries most days, and stop discharging it / them overnight

• Registered Users Posts: 2,682 ✭✭✭

Just to try and close off this thread - and for completness.

I am very happy with my setup now. By setting the Eddi "Supply Grid - Device Limit" setting to 9A - I am able to only consume the stored battery energy for the early morning pre-sunshine "Boost" for hot water.

As long as the battery has some power left overnight this works great! See below there is no sun being generated - but the Eddi is looking to heat the water by boost. The 5kW Dyness battery is almost maxing out and fully covering the demand to the eddi. There is always a second boost about 90 minutes later to the tank - i guess the water settles and it needs warming again... still covered by battery.

And this is what happens when the battery is drained during the boost; ie it didnt have enough to cover the entire boost - so the grid fills in the rest. I still get what I want cheap D/N rate for hot water! :)

• Registered Users Posts: 5,744 ✭✭✭

You'll have a balancing act in October/November. Once the clocks go back, I don't discharge the battery during night rate, but I also might not charge it at all, depending on the weather forecast. Other days, I might charge partially or fully.

Obviously, this is all to ensure that I use zero day units

• Registered Users Posts: 2,682 ✭✭✭

Sure, but the beauty of this confgiuration is that it doesnt change the Eddi setup. I still need Hot Water in the morning so my boost schedule will stay as setup. I might add another schedule in winter to Boost the evenings - when the Sun isnt there anymore - Nov/Dec/Jan/Feb for sure.

The key here is people are not evening looking at the Eddi/Diverter that is being installed - they are just hoping it will magically work! It needs some amount of configuration or you will be disappointed. The 9A limit on the Eddi device is perfect for my size battery. If you have a bigger battery you can increase the A or even leave it default. If you have a smaller battery it liekly wont make it thru the night anyways!