On-grid domestic battery storage

Scribbly

gefnew said:

This may help you.
Powervault 2022 | Home battery storage [Review + Prices] (electriccarhome.co.uk)

Thank you.  I noticed in there that Powervault pays £20 per month if you have their Gridflex option - I have it but haven't been receiving the £20, so I think it's time to drop them an email.....

madswitcher

On a general point, Octopus seem to be the only electricity provider that supply low cost electricity during the night when there is excess power available in the national grid - that is besides that for charging electric vehicle.  Since prices have gone sky high, should the other providers be forced to provide cheap overnight power. 

Perhaps Martin Lewis could consider suggesting this to the government since he has high credibility with them in representing the consumer, alternatively, a petition ????

QrizB

madswitcher said:

On a general point, Octopus seem to be the only electricity provider that supply low cost electricity during the night when there is excess power available in the national grid

The idea that there is an "excess of power" available overnight is a common misconception. It may have been true in the relatively distant past when the majority of the UK's power came from coal and nuclear plants, but currently it only holds true on the odd occasion when there are strong winds blowing across much of the country.

From energy-stats it appears that, in the past 18 months, ther have only been five occasions (16/11/20, 26-27/12/20, 21/05/21, 19/10/21, 01-02/01/22) where there has been a gross surplus of electricity and prices have been negative. There have been a further dozen or so occasions when the price has been zero or close to it.

Switching to Nordpool data, in recent days (12-16/05/22) the lowest prices have been mid-afternoon not overnight.

Perhaps Martin Lewis could consider suggesting this to the government since he has high credibility with them in representing the consumer, alternatively, a petition ????

The encouragement should really be to get people onto smart meters and smart tariffs so they can take advantage of these intra-day price variations, rather than trying to perpetuate practices from the last century.

arty688

I like many people are basing my Solar/battery decision on the current market and tariffs. Which financially may prove to be a mistake especially the battery . Who knows what the market will be like in a few more years and probably 10x the EV's on the road which will be mainly charged at night not to mention Heat pumps. I think Octopus GO will disappear and be replaced by some smarter tariffs which will need smart things on the end of them (EV , ASHP etc...) like intelligent Octopus. I just hope there is a real long term energy strategy going on and not just bluster to get through the next election.

madswitcher

Hi QrizB,

thanks for your reply - you have obviously researched this area thoroughly, but the question still remains that cheap(er) electricity is available overnight from some suppliers, primarily for electric vehicles, and yet not available for normal household battery storage use which is the fundamental point I was trying to make.

QrizB

Early this morning my Sofar ME3000SP decided, for no immediately obvious reason, to grab about 2kWh of electricity from the mains. From about 5am to 6am it charged the battery at roughly 1kW.

At the start of the period the battery would have been realtively flat (probably 20% SOC) as I'd deliberately drained some of it between 8pm and 10pm to heat water (I'm expecting a good solar harvest today and last night's demand for showers was quite high).

This isn't a huge problem but it's 2kWh from the grid - more than I'd used all month - and I'd like to know why, so I can discourage it from happening again.

• Has anyone else had their Sofar do this?
• Is there an easy fix?
• I think there's a Sofar support group on social media somewhere (Facebook perhaps); does anyone have a link?
  

Dave_Fowler

QrizB said:

Early this morning my Sofar ME3000SP decided, for no immediately obvious reason, to grab about 2kWh of electricity from the mains. From about 5am to 6am it charged the battery at roughly 1kW.

At the start of the period the battery would have been realtively flat (probably 20% SOC) as I'd deliberately drained some of it between 8pm and 10pm to heat water (I'm expecting a good solar harvest today and last night's demand for showers was quite high).

This isn't a huge problem but it's 2kWh from the grid - more than I'd used all month - and I'd like to know why, so I can discourage it from happening again.

• Has anyone else had their Sofar do this?
• Is there an easy fix?
• I think there's a Sofar support group on social media somewhere (Facebook perhaps); does anyone have a link?
  

The only time I've had an unexpected battery charge was due the battery BMS detecting a lower than normal battery voltage - it had discharged over-night and had reached the preset minimum charge voltage - even though the SOC was not down to minimum.  The BMS set up a charge of 400W for about 2 hours to bring the battery voltage pack to normal,  Do you have access to the battery voltage graphs for the early morning?

QrizB

Dave_Fowler said:

QrizB said:

Early this morning my Sofar ME3000SP decided, for no immediately obvious reason, to grab about 2kWh of electricity from the mains. From about 5am to 6am it charged the battery at roughly 1kW.

At the start of the period the battery would have been realtively flat (probably 20% SOC) as I'd deliberately drained some of it between 8pm and 10pm to heat water (I'm expecting a good solar harvest today and last night's demand for showers was quite high).

This isn't a huge problem but it's 2kWh from the grid - more than I'd used all month - and I'd like to know why, so I can discourage it from happening again.

• Has anyone else had their Sofar do this?
• Is there an easy fix?
• I think there's a Sofar support group on social media somewhere (Facebook perhaps); does anyone have a link?
  

The only time I've had an unexpected battery charge was due the battery BMS detecting a lower than normal battery voltage - it had discharged over-night and had reached the preset minimum charge voltage - even though the SOC was not down to minimum.  The BMS set up a charge of 400W for about 2 hours to bring the battery voltage pack to normal,  Do you have access to the battery voltage graphs for the early morning?

Thanks, that could be it.

My battery is homebrew so no, I don't get after-the-event logging from the battery. I've never succeeded in connecting the Sofar to the on-line servers either.

Do you know which of the battery parameters under "DEFAULT" is the key one here? I'm quite happy to experiment!

1961Nick

QrizB said:

Early this morning my Sofar ME3000SP decided, for no immediately obvious reason, to grab about 2kWh of electricity from the mains. From about 5am to 6am it charged the battery at roughly 1kW.

At the start of the period the battery would have been realtively flat (probably 20% SOC) as I'd deliberately drained some of it between 8pm and 10pm to heat water (I'm expecting a good solar harvest today and last night's demand for showers was quite high).

This isn't a huge problem but it's 2kWh from the grid - more than I'd used all month - and I'd like to know why, so I can discourage it from happening again.

• Has anyone else had their Sofar do this?
• Is there an easy fix?
• I think there's a Sofar support group on social media somewhere (Facebook perhaps); does anyone have a link?
  

The BMS will call for a grid charge if the voltage of one battery drops out of range. I've observed that high rates of discharge as the bank approaches the minimum SOC often results in the pack becoming unbalanced. The process of balancing after the inverter goes into standby may be the cause of one of your batteries to require a top up. The top up will be whatever that battery needs x the number of batteries - easily 1kWh if you have 4 or more Pylons.

The first thing to try is to stop high rates of discharge when the bank is nearing the minimum SOC. A gentle landing when the inverter goes into standby will minimise the balancing requirement.

If that doesn't work, update the software to 3.09 (skip 3.06 it's flaky).

https://www.dropbox.com/sh/pfmcyj4hays26z5/AACYaYZkXkKvmPQZ1CCXJsG2a?dl=0&fbclid=IwAR2l90Y-cwMwwFNTQBIpHsNYUdLEHJeWMR8LjXgNPQs9DTJWmuiRyMyt1tc

Solarchaser

Yeah as others have said, observed this twice on my sofar when I had it, both times it had been run to the 20% min I'd set, then during the night the soc had dropped, so it applied 1kw... might have been 800w actually for around an hour and a half until the batteries were around 30% I think. (Was a few years ago now)