I've heard Sonnen can do it, but they're base model does not do it. It's an upgrade you can get.

Posted by: @broadsman

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Apart from Tesla and Give Energy, what battery manufacturers offer full backup possibilities in the event of power cuts, and what are the restrictions regarding positioning of the "Gateways" ( of any makers) in relation to the grid meter. Any experiences would be appreciated.

It would be good to understand what you are trying to achieve.  By that I mean, what are the off grid loads in kW, estimated run time required in island mode and budget?

With this info I can offer some advice 👍

@saenergy I have recently installed a 12Kwh heat pump and the battery would be to help reduce running costs, but also to provide power to the house in the event of power cuts, of which there have been 5 in the last 12 months. With our turbulent weather patterns I see this likely to continue in future years.

I would like everything installed in my garage which is 12+ metres from the house/meter. However I am told that the Tesla Gateway has to be mounted very close to the meter which is on the house front wall, and I do not want another box there.

Ideally I would like about 20Kwh storage with 5Kw power. Budget is tight and (loss of ) interest on capital goes some way in paying for the extra cost of running the heat pump. A bit of a financial conundrum. Any help much appreciated.

Posted by: @broadsman

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I would like everything installed in my garage which is 12+ metres from the house/meter. However I am told that the Tesla Gateway has to be mounted very close to the meter which is on the house front wall, and I do not want another box there.

Where is you distribution board? In the I would have expected, based on my installation, that proximity of battery to your distribution board to be more important than proximity to the meter. With the Tesla backup gateway the cables between the main fuse and the MDB go via the gateway as this contains the breaker to isolate the house supply in the event of a mains failure. The attached photo shows the gateway in my garage. It's next to the meter but I would have thought there wouldn't have been any difference in the gateway location had the meter been outside the garage.

I recall that the gateway also has a current sensor for the solar generation but I think that's hidden in the trunking.

@broadsman - I think you should also consider a partial DIY approach.

Elsewhere on this forum we've discussed the battery enclosures made by Seplos, and the UK company, Fogstar.

You then fill the steel enclosure with the LiFePO4 cells in-situ.
You're unlikely to move it again because it will weigh over 100Kg 😲 

Fogstar can also supply the cells, or you can import directly from China at lower cost.

A typical set of sixteen cells, each with 280Ah capacity will cost about £1500 from China, using marine shipping.
I can give you contacts with an agent if you want to investigate that option.

16 cells at 280Ah makes a battery with total capacity of 14kWh

Separate to the battery, you will need inverter(s).

On another topic, you will recall that I suggested you consider using hybrid off-grid inverters from SunSynk.

The total throughput of the inverters (kW) dictates how much power you can draw to run the home.

The capacity of the batteries (kWh) dictates for how long you can operate off-grid.

Please feel free to dive in and ask whatever you want here.

You don't have to get the terminology correct.
The less technical is your question, the more it will help others in future.

@transparent Thanks, I need to see-read your earlier advice.

Posted by: @broadsman

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@saenergy I have recently installed a 12Kwh heat pump and the battery would be to help reduce running costs, but also to provide power to the house in the event of power cuts, of which there have been 5 in the last 12 months. With our turbulent weather patterns I see this likely to continue in future years.

I would like everything installed in my garage which is 12+ metres from the house/meter. However I am told that the Tesla Gateway has to be mounted very close to the meter which is on the house front wall, and I do not want another box there.

Ideally I would like about 20Kwh storage with 5Kw power. Budget is tight and (loss of ) interest on capital goes some way in paying for the extra cost of running the heat pump. A bit of a financial conundrum. Any help much appreciated.

ok. 

So for most heat pump clients we recommend a minimum of 20kWh in combination with either a single long low tariff or one with multiple low rates over the day.  Agile is ok but for most is a risky option. 

as budget is tight and you don’t want to locate a gateway or ATS near the grid connection, I expect a full load cut over may not be a good choice.  

Instead look at systems with decent EPS.  Most will give about 20A of output.  Enough to keep some small power in for internet, lighting and the fridge freezer.

i would go with a fully integrated setup where the manufacturer also supplies the batteries as opposed to an inverter with a random list of compatible batteries.  This will be the least hassle for you long term.  

you will to factor in splitting of circuits for the essential supplies etc. 

ECO ESS do some nice kit with great pricing.  The new semi solid state batteries are a good option for low temp install.  

My advice though would be to reconsider the Tesla option.  It gives you a great battery, whole home backup and you won’t need to alter any internal wiring to suit.  Yes, you need the gateway between the grid in and the consumer unit, but it’s worth the effort and out of all the full grid systems it’s probably the nicest looking. 

@broadsman  - I'm unsure if those suggestions from @saenergy will be clear enough for you.

Allow me to expand some of those terms and concepts:

20kWh is the capacity of a battery being recommended.

A heat-pump uses very power when running continuously, as it should be doing.
A 12kW ASHP will draw about 16A (assuming a COP of 3.0)

But it would require double that amount to start up... until the compressor has brought both fluid loops up to operating pressure.

The length of time you would be able to run the heat-pump from that notional 20kWh battery therefore depends on how well it's been commissioned.
If it cycles on/off then you will use the stored energy much faster.

ATS - Automatic Transfer Switch.

This will transfer the load to be powered from the battery when there is power-cut.

That implies that the battery is merely to be used as a backup supply for when there is an outage.
However, you may wish to run the heat-pump (and other appliances) from the battery on a regular basis, rather than install it just to operate an 'Uninterruptible Power Supply' (UPS).

Full Load Cutover also implies that the storage battery is operating only as a reserve power source.

EPS is Emergency Power Supply. It operates only during a power cut.

This may not be intentional, but I understand the post from @saenergy to be predominately based on your comment about having power during an outage.

That's a very expensive investment, which will remain unused for the majority of the time.

And it may not reflect the emphasis which you intended in the title of this topic.

Posted by: @saenergy

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i would go with a fully integrated setup where the manufacturer also supplies the batteries as opposed to an inverter with a random list of compatible batteries.  This will be the least hassle for you long term.

There is very little 'hassle' when you have a storage battery in the home.

You'll take great interest in what it's doing for the first week, and be checking the inbuilt display or an App several times each day.

Unless there is a fault, you'll probably be ignoring it entirely after a month!

The 'list of compatible batteries and inverters' is a concept which produces almost zero benefit!

A battery has an inbuilt Battery Management System (BMS).
This monitors the amount of charge going in/out of each cell and protects the battery against over-charge or too much discharge.

The one thing that a BMS isn't very good at doing is working out the State of Charge (SoC).
That's because most domestic storage batteries are used within the 20% to 80% range, where the SoC curve is almost flat !

If an Inverter has a list of 'compatible batteries' it simply means that the readings from the BMS in the battery are capable of being transferred to the inverter.
Thus the inverter's App can display data from the battery.

It does not mean that there is anything clever being done with that data!

You don't suddenly get a Smart Storage system because the inverter and battery are 'compatible'.

Nor is it going to be any better at telling you the SoC.

If you do want a reasonably accurate assessment of how much energy is in your battery(ies), then get a Coulomb Counter system installed.

This is a separate device which counts the charge going between inverter(s) and batteries and uses some clever formulae to display the result.

Here's a (cheapish) Coulomb Counter made by Junctek.
It uses a low-resistance 'shunt' to measure the current.

And here's another cheaper one I've tried from Peacefair, which is sold under a number of different brand names:

Either of these might be able to report the SoC to an accuracy of 10%

Batrium (Australia), and Victon (Netherlands) both make higher quality units with greater accuracy, for £80+.

@transparent Wow, what a great bunch of knowledgable guys we have on here. Many thanks to you all for the suggestions. I have a lot of reading and understanding to get through

😘 The 'deal' here @broadsman is that the knowledge needs disseminating wider afield!

Please talk about the issues with others in your area.
I'm especially keen to see Local Councillors becoming more informed on energy issues.

We should be implementing strategies to provide energy for social housing tenants which is cheaper and more resilient.
Most of the technology to achieve this is already available...
... but the decision-makers can't implement what they don't know about.

There is a lot more I need to know about battery usage before I take the plunge.

We are currently on Octopus Cosy tariff, with three half-price periods during the day. I would require the battery to charge during those periods and to be available to run the heat pump during the expensive 4pm to 7pm period, and at other times during the day. I also want it to be available for normal domestic supply in the event of  power outages, although timing of switchovers is not critical.

In theory, on a Tesla PW3, I should be able to charge from zero to full over 2.5 times daily, assuming a full discharge in between. This would be ideal as then, all our consumption would be on half price tariff. However, is this practical? Anyone doing anything similar?  Also is there a tariff anywhere which allows cheaper daytime charging (as well as overnight) such as Cosy and allow export as well?  Incidentally, no panels to help with charging.