Domestic Battery Storage Systems - Energy Storage Response Times (Ramping Delays)

zeupater

Hi All

I've seen mention of energy storage response times ranging from virtually immediate where UPS/EPS backup is required right through to somewhere around ~30 seconds of power ramping (both up and down), which obviously results in huge differentials in battery system viability or payback calculations.

This thread is intended for discussion of specifications and/or user experience in order to build a picture of what is (/can be/should be) a fundamental (battery/inverter/charge controller) consideration when looking into energy storage systems whether paired with renewable energy generation (solar etc) or as a stand-alone ESS/UPS backup solution.

Have fun - we're all here to learn -

HTH - Z  

QrizB

I've tried this a couple of times this afternoon, using my 3kW kettle as the load.

• Switching the kettle on, my Sofar ME3000SP switches modes from "charging" to "discharging" within a couple of seconds of the load being applied, and ramps up to maximum discharge (see note below) within a couple of seconds more.
• When the kettle switches off, the Sofar remains in "discharge" mode (without any appreciable discharge happening) for 7-8 seconds before returning to "charging" mode.

I only have a small battery and so I've restricted the Sofar to a maximum 20A discharge, approx. 1kW, via the front-panel settings. It's possible that it would take longer to ramp up if this was set higher.

EcoScruples

Great thread, I'm particularly interested in anyone with  Huawei hybrid inverter and battery set up.
2 things, how long is the delay when switching big items on and,
Does the battery/inverter pick up the low overnight loads.
My base load is around 200 watts from 11pm to around 7am. I aim to get this covered but I'm not sure how the inverter reacts to these low loads.

Magnitio

EcoScruples said:

Great thread, I'm particularly interested in anyone with  Huawei hybrid inverter and battery set up.
2 things, how long is the delay when switching big items on and,
Does the battery/inverter pick up the low overnight loads.
My base load is around 200 watts from 11pm to around 7am. I aim to get this covered but I'm not sure how the inverter reacts to these low loads.

I have the 5kW inverter. It reacts very quickly to changing loads (<5 seconds.) Difficult to give an exact time as there is a small delay on the IHD. However, when looking at consumption figures from Octopus the next day, it is negligable - average of .08kWh per day that isn't handled by the battery.

 

Works perfectly with low loads. Following chart shows yesterday's battery charge/discharge graph:

Load overnight was as low as 44W. 5-6AM roughly is immersion heater at 1.4kW. Excess solar was exported to grid from 8-10. Battery slowly charging from solar between 10 and 5. Dumped a few kW between 6 and 7 at higher rate. Reasonably configurable. Received £2.90 for 23.5kW exported solar yesterday (low prices between 10 and 4) and still consumed 13.6kW with 4 lots of washing.

EcoScruples

That's perfect, I'm getting the 3.68kw inverter.
I was expecting a little import but a few watts a day will be even better. Obviously I'll need to judge my loads a little better with the smaller output but that looks really promising.
A few seconds response sounds good too. I wasn't expecting instantaneous but will be happy with that.
Thanks for the info, I may well come back to you with more questions.

EcoScruples

QrizB said:

I've tried this a couple of times this afternoon, using my 3kW kettle as the load.

• Switching the kettle on, my Sofar ME3000SP switches modes from "charging" to "discharging" within a couple of seconds of the load being applied, and ramps up to maximum discharge (see note below) within a couple of seconds more.
• When the kettle switches off, the Sofar remains in "discharge" mode (without any appreciable discharge happening) for 7-8 seconds before returning to "charging" mode.

I only have a small battery and so I've restricted the Sofar to a maximum 20A discharge, approx. 1kW, via the front-panel settings. It's possible that it would take longer to ramp up if this was set higher.

The battery remaining in discharge mode is that a naturally built in thing to just make sure the load isn't going g to kick in again?
Clever if it is.

How small is your battery?
Is it AC coupled?

Alnat1

My system was only installed in March, Lux with Pylontech, SW facing roof. I've found that in the early morning, battery charging with low solar levels but enough to cover the load, then there's small amounts being pulled from the grid as the house load alters. Also small amounts can be exported at this time. 

Clicking on the kettle etc. does pull a bit from the grid for a few seconds but doesn't amount to much over the day.

Most days I see around 0.2kWh both in and out that maybe shouldn't be there if the system worked perfectly but I can accept these small amounts when thinking of the general savings I'm making.

Solarchaser

Sofar me3000sp when busy, very responsive, perhaps max of 15 seconds to go to full 3kw discharge from charging.
When idle, perhaps over 2 mins before giddying up.

Growatt sph3600 pretty slow to do anything compared to the sofar, around 30 seconds to ramp down from what it was doing, another 10 seconds of doing nothing, and around a minute to ramp up to full 2.5kw output, and well over a minute to return to charging again.(3 years ago, perhaps they are quicker now)

Lux3600 acs when busy is pretty instantaneous, slightly slower than the sofar to get to full 3.6kw (really 3.4kw) discharge, perhaps 18 seconds from charging to discharging full bore.
When idle around 20 seconds before it will start doing meaningful discharge (over 1 kw) but only a few seconds after it will be full bore.

Using ihd is OK, but mine only updates every 10 seconds, so usually through the day I'll see the odd flash of say 5-8 hundred watts when perhaps the dryer cycles etc, and at next update it's 150w say, and at next update it's back to 0, but if you are watching the actual lux display you can see it reacts usually much faster than that.

QrizB

I thought I replied to this last night, wonder where it went?

EcoScruples said:

QrizB said:

I've tried this a couple of times this afternoon, using my 3kW kettle as the load.

• Switching the kettle on, my Sofar ME3000SP switches modes from "charging" to "discharging" within a couple of seconds of the load being applied, and ramps up to maximum discharge (see note below) within a couple of seconds more.
• When the kettle switches off, the Sofar remains in "discharge" mode (without any appreciable discharge happening) for 7-8 seconds before returning to "charging" mode.

I only have a small battery and so I've restricted the Sofar to a maximum 20A discharge, approx. 1kW, via the front-panel settings. It's possible that it would take longer to ramp up if this was set higher.

The battery remaining in discharge mode is that a naturally built in thing to just make sure the load isn't going g to kick in again? Clever if it is.

I guess that's why!

How small is your battery? Is it AC coupled?

Yes, AC-coupled. I built my battery from cells, and have got a good bank of 25Ah cells (1.2kWh) plus a bad bank of 50Ah ones. The 50Ah cells are a bit of a disappointment; they were sold as 60Ah (they aren't) and as "new Grade A" (they aren't).

If the 50Ah cells were fully working I'd have 3.6kWh of capacity but in practice it's less than 3kWh and could be less than 2kWh.