We have an episode of Homeowners' Q&A coming out on Wednesday that tackles this subject. Simon Smith, who was on the panel, spoke very highly of Givenergy's software and controls. Tesla will naturally always be a contender too - our neighbour has one and the controls and software are very good and easy to use.  

As for the power cuts, how long were they, and where in the UK are you based?

@editor I realise that the Tesla route is not the cheapest - but it is good, as is the Tesla app to control many aspects of controlling the system; there are also apps such as NetZero which further augment the flexibility of the system greatly.

With 27 kWh’s of battery and the 3 Octopus Cosy lowest cost intervals amounting to 8 hours per day, we never have gone outside those 8 cheapest hours to draw on the grid. We have a Daikin 8 kW heat pump and are an all-electric household who like to keep warm at 22.5 degrees C. 24/7. Regards, Toodles.

@editor I am in semi rural Norfolk. Yesterdays cut was only 20 mins here, but in the village it was a couple of hours, as had the previous one's been. Shall be interested in the Q & A, because it was the Giveenergy battery that was supposed to have the poorer software, at least in my friends experience.  Also thanks to Toodles for his comments.

@toodles  Thank you. We are all electric too and not too bothered about when we switch on the Dishwasher etc. My average for the winter over many years is 12 Kwh per day, until the 12Kwh heat pump arrived. Just wondering what your average daily use is with the pump that you are covering with your 27Kwh of battery. Is that excessive or just enough. Do you export in the summer?

Posted by: @editor

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Simon Smith, who was on the panel, spoke very highly of Givenergy's software and controls

I believe that the GivEnergy inverters will only operate at half their specified power through the always-on (off-grid) output.

Compare that with those from SunSynk which will deliver full power from their "backup" port whether the grid is live or not.

I'm presently using Growatt SPF5000ES inverters, which are fully off-grid.
Ie they have no export capability.

In favour of GivEnergy, they're a British company in control of their own product development.
SunSynk is based in South Africa, with manufacturing by Deye in China.
Growatt is entirely a Chinese operation for design & manufacturing.

Posted by: @broadsman

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we need better than 13.5 Kwh capacity, probably around 20 Kwh.

Those are figures which apply to the battery.

You will need to separately assess how much power your home will need to draw simultaneously during a power-outage.
That defines the throughput capacity required from the inverter(s).

13.5kWh battery capacity is commonly referred to because it equates to a set of sixteen LiFePO4 cells, each rated 280Ah.

Those cells weigh 95Kg plus the enclosure they're in.
So you usually expect this to be an "assemble on site" option.

Power outages will become progressively more common at the LV level of the grid (below 1000v AC RMS).

The problem with the final couple of hundred meters from the Local Substation is that our homes are supplied with single-phase, whilst the 11kV transformer is 3-phase.

When the demand (load) is different across the phases:

• there are losses due to phase imbalance in the transformer
• current flows in the Neutral

The Neutral isn't usually fused at the substation.

In underground Feed cables, the Neutral is also often a smaller conductor (lower cross-sectional area).
It gets hot, causing thermal breakdown of the insulation.

These technical problems can be resolved.

But there's no money to be made by doing so.

Whereas the DNOs can make a case to Ofgem to replace the cables and transformers with larger/newer ones in order to achieve 'greater system resilience'.
Ofgem agrees and allows our consumer bills to be increased in order to fund the upgrades. 🤨 

We’ve got a single 9.5kWh GivEnergy battery and it has been OK software-wise. Others have had real problems with the control side, in particular when running multiple batteries either in series or parallel.

You can read about GivEnergy software issues on Facebook or their community forum without buying a battery. Bear in mind that these are the loudest complainers and the silent majority are OK. Not much compensation if what you want is more than one battery.

If you can afford PV panels they make the battery worthwhile.

@broadsman Our co nsumption was in the same ball park when we still had gas heating and DHW.

Using a Sunamp Thermino ePV210 for the DHW since putting in the heat pump and that (for the two of us showering and all other domestic needs runs at 3.5 kWh’s to ~4.5 kWh’s per day summer and latterly, winter use.

The heat pump varies between 7 kWh’s last July (a cold day or two I think) and 829 kWh’s in January ‘24. Total so far this year (according to the Daikin Onecta figures is 3,070 kWh’s As another example, March this year was 474 kWh’s. January ‘24’s consumption approximates to 26.75 kWh’s per day (obviously higher somedays, lower others but average). I reckon my 27kWh capacity would cover my total needs on the days of highest consumption as I can charge from grid at 10 kW; therefore, 3 hours is more than sufficient for a full charge.

The worst day (-8 degrees all day and night) last December consumed ~42 kWh’s for the heat pump which resulted in the whole house consumption totalling ~ 58 kWh. At that time, we were on Agile and I managed to charge during the nights and top ups during a few cheapest hours in the day. I hope this information assists in your decision making - I am aware that I went for the more expensive option but, it is serving us well. Regards, Toodles.

@toodles Thanks, that's useful info.

@broadsman Sorry, I forgot to answer your question about solar generation; yes we do export during the spring - summer and autumn. As the export rate has been favourable in the past, I found it to our advantage to ‘buy cheap - sell slightly higher’; though the difference is marginal now when taking into account the ~10% conversion losses with the battery. The Sunamp Thermino can be set (via MyEnergi Eddi) to charge from solar too. We have 8.1 kWp with 21 panels variously orientated. Regards, Toodles.

We have two 9.5kWh GivEnergy batteries and a Hybrid 5kW inverter.  It has worked well with our 24 panels (9kWp) since June 2023.  GivEnergy is responsive to software problems through a support line.  There is a very active GivE forum where problems are aired enthusiastically but these are the vocal minority as far as I can tell.  Many posters like to devote many hours to their hobby.

I have opted for a more hands-off approach and use My Energy Optimiser (MyEO) to manage the batteries in conjunction with Octo Agile.  This has worked really well.  It takes account of the day-ahead rates and manages charging and discharging based on usage patterns.

The batteries aren't big enough to supply my 14kW Ecodan ASHP, of course, which can easily use 60kWh on a cold day.  So the usual pattern is to charge overnight and then recharge enough in the early p.m. to ensure at least 60% in the batteries by 1600 to make sure no import is needed during the peak hours.

The batteries can be wired up to go into island mode when the grid fails, but I don't have this (yet!).  The inverter is limited to 3.6kW charging or discharging, so that's a consideration as well.  The 5kW inverter rating refers to the DC to DC charging of the batteries from solar.

@broadsman those four powercuts are sufficient for your Parish Council to ask the Area Manager of UK Power Networks to attend the next meeting.

There are many possible reasons, and you need to know what the village is up against.

• are the four instances related to the same cause, or just coincidences?
• what's the capacity rating of your village local substation(s) and how close is the demand peak to that?
• what's the available capacity for reverse-power (local generation exporting to the grid)?
• how long is the 11kV network from the Primary substation to your village, and what's the voltage drop looking like?

You need to open up a dialogue with the named engineer for your patch, rather than just have a one-off meeting to 'demand answers'.

Ask them how much is it worth to them if the local community were to adjust its demand so as to be 'grid friendly'?

There are funds available for innovative projects.
If it involves generation/storage, then they're likely to be more interested.
DNOs are not permitted to control or own generation or storage assets for themselves.
So they need partnerships.

DNO's get evaluated by Ofgem for constructive liaison with the public and local authorities.
It counts towards their RIIO-ED2 targets, and that constrains dividends payable to shareholders.