/ Home & Energy

Home batteries: are they the next big thing?

home battery

They claim to save you hundreds of pounds on your electricity bill, help you towards electricity self-sufficiency, and even let you play a part in the National Grid. Are you tempted by a home battery?

Energy storage systems – also known as batteries – store electricity in your home so you can use it when you need it. Usually this is electricity generated by a renewable system, such as solar PV or a wind turbine, but you can also store electricity from the grid.

And it looks as though batteries are moving into the mainstream.

Eon launched its solar and storage offering last month and it claims that installing a battery can help you use 30% more of the electricity you generate than with solar panels alone. Combined, it says you could make £560 a year in savings and earnings.

This week, Nissan also announced it’ll be selling home batteries – customers can choose a battery previously used in an electric car, or the pricier option of buying brand new.

And Tesla, which is more famous for its cars, sells a home battery it claims can power the average two-bedroom house for a day.

It’s early days yet for home battery storage but, with over 900,000 solar PV installations in the UK, its potential to grow is huge.

Battery storage benefits

If you have solar PV, wind or hydro turbine, it may generate most electricity when you’re not at home to use it. Unused electricity is exported to the grid and you’ll probably import electricity in the evenings.

Batteries store excess renewable electricity so you can use more of what you generate and help cut your electricity bills. They range from around 1kWh to 8kWh, which the Energy Saving Trust says is enough energy to boil your kettle between 10 and 70 times.

There’s also the potential, with time-of-use tariffs, to charge your battery from the grid when electricity is cheaper, and use up your store at times of day when electricity is more expensive.

Consumer concerns

Solar PV has the Feed-in Tariff, and heat pumps, solar thermal and biomass boilers are supported by the Renewable Heat Incentive, but there are currently no government incentives for home batteries.

So how much money you could save depends on the system you have installed and how it’s used. Many technologies are too new for there to be independent data to estimate typical savings yet.

Battery storage isn’t regulated either, although the Renewable Energy Consumer Code (RECC) was recently extended to include battery storage systems. Installers signed up to the code agree to abide by high consumer protection standards. RECC said that it has seen ‘increased interest in these products’, but also ‘a rise in complaints citing mis-selling’.

We’ve heard from Which? members with battery systems who have very different views on them. One told us about reducing their energy bill to less than £20 per month, while others have complained about systems not working as expected and installation problems. Some found the cost off-putting.

So, do you have a home battery installed? How do you use it and what do you think of it? Is there anything you wish you’d known in advance?

Comments
Profile photo of PatrickTaylor
Member

Sadly not enough information to take a view on this . I hope Which? will be monitoring and reporting on this growth area. However without any prices quoted and payback it is hard to say much more.

This should help readers get an overall view :
bre.co.uk/filelibrary/nsc/Documents%20Library/NSC%20Publications/88166-BRE_Solar-Consumer-Guide-A4-12pp-JAN16.pdf

Profile photo of alfa
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A little more investigative reporting would not have gone amiss here instead of just copying info straight from the Energy Saving Trust website.

I have found 14kWh batteries in size and 2 of these claim to be sufficient to power a 3 bedroom home for a day.

Profile photo of malcolm r
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We need, for example, cost and life of batteries, cost of installation and maintenance, capacity loss over time, conversion efficiency of electricity into battery storage and of battery energy into usable ac, then we can begin to assess whether they are an economic proposition, or when they might be.

Energy saving is more important than energy storage in my view – unless your house is already very efficient. It would be useful to review, factually and economically, all the energy saving measures sensible for householders – solar hot water, heat pumps, insulation, glazing, lighting. If you have solar power (wind and hydro – how many have those?) then rather than use all of it yourselves you can export more.

And if it is about saving money and oil, look to your choice of car.

Profile photo of VynorHill
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An interesting concept though quite a technical one. Battery storage, a charging device and wiring into the house all need to be sorted, so the capital outlay would probably be a couple of years before it was paid for. Not all buildings are suitable for solar panels and windmills need planning permission. I would like to see research into fuel cells, so that renewable energy could be used to create things like water hydrolysis and this, in turn used to power the house. There are many schemes that use natural energy and heat re-capture. These are most useful when designed into a new building rather than added on, but there is also a danger of environmental problems when a house is turned into an insulated capsule. It’s a new and exciting science -something to be encouraged.

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We’ve had solar panels for around 6 years and with a 4kwh array have found them well worth while – but only because of the FIT payments! The actual saving on our electricity use alone would take forever to repay the cost of installation. I have investigated battery back up several times but, as already stated, there is insufficient reliable and independent information available to warrant the cost of installing a battery, both from the technical side and the financial aspect. Sales people just cannot be trusted I have found.

Profile photo of John Ward
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The Introduction refers to a Which? member “reducing their energy bill to less than £20 per month“. . . . . Yes, quite.

Unless we know a lot more about the size of the household, type of property, location [Channel Islands?], lifestyle [TV, computers], whether gas or other fuels are involved, what fuel is used for cooking, heating and hot water, this is a completely meaningless statement that helps no one. Even a rough “before” cost would have been appreciated.

Profile photo of duncan lucas
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None of them is going to compete with the ultimate cost effective means used by our departed friend in NI — hydro power even has a downward flowing stream . Batteries are an ongoing development I get multiple emails from tech websites detailing the latest US “innovation ” in battery design followed by Japan , you even have “organic ” batteries of various descriptions all spurred on by the US / Japanese car industry . I remember when repairing UK fork lift trucks ( Lansing Bagnall etc ) the massive batteries that powered them and the massive amounts of electricity to charge them. so I will ask the relevant engineering question -has the “perpetual” generator been designed where the efficiency is –100 % ? if not until the “Power of the Universe ” has been harnessed as quoted many times as the type of energy used by “flying saucers ” ( yes it does exist –the power I mean) then there is always a cost for the use of energy in this world even if it is only in the maintenance aspect . Do solar panels “live forever ” nope , is there a pocket size nuke power station with NO radiation -nope, although the Russians are getting close. But , if you are American you must know full well self generation ( household ) is banned by US government legislation because of lobbying by US Big Utilities as well as water storage -YES rainfall banned as well even from your own roof. As you know what happens in the US happens here tomorrow , not something to look forward to –is it ? Now where is that ion drive I have been working on ?

Profile photo of duncan lucas
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Thought as much guess who is heavily promoting this ?? that US Giant Telsa — its all really commercialism –isnt it ? Well we might as well get some extra money back from our investment in battery run automobiles design , why not be honest ?

Profile photo of John Ward
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Early adopters of PV solar panels are benefiting from a favourable feed-in tariff. Each cut-back in the FIT has, understandably, reduced the appeal of solar electricity generation but it remains economically worth while because the capital cost of installation has fallen considerably. I would doubt that in ordinary situations with solar power the extra outlay for a battery installation would repay itself in a reasonable period. In a home without any renewable electricity intake I cannot see it ever being viable; we need to keep a close eye on the marketing to make sure people are not being swindled into paying for something that will do them no good.

I am sure that domestic solar power installations will continue to grow in number but the rate of expansion might now slow down. I am ever the optimist so I would expect the raw cost of electricity to start declining in real terms as the renewable content of our supplies continues to increase as the huge new off-shore wind-farms start to come on stream and the extensive commercial solar panel arrays start to ramp up their output. Indeed, there have been days lately when the UK was running on the sun and wind alone and actually receiving too much energy from renewables. This trend, if confirmed, could affect the economics of domestic installations so I think we should be cautious about battery storage systems.

I go along with Malcolm and feel that there is more mileage in energy conservation and reduction through practical measures that will help most households and improve the condition of our housing stock at the same time.

Profile photo of PatrickTaylor
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I agree with the cautious approach and doing what you can for the housing stock.

Fortunately I am about to start with a clean slate and needing to replace a 20 year old oil heater have been looking at all the options. This goes from wood-pellet to air and ground pumps by way of solar arrays. Or even another oil burner! or just electric.

The decision so far is to make one area heavily insulated and double glazed and leave the balance of the house for warmer weather days. So basically maximise one part for cold weather and being smaller than the whole is intrinsically cheaper to heat. Whether this approach works in the UK where houses are generally small is moot.

I would consider large batteries if the cost is right as I have room for PV panels aswell as panels for heating water.

However for the big problem I wish Which? would get onboard with energiesprong.uk and help drive that in the UK by publicising the considerable benefits and low costs.
” The deceptively simple idea behind the initiative has been to finance the roughly 300,000 mass-produced renovations from the estimated €6bn of savings from energy bills that they will make each year.
In the Netherlands, upfront capital comes from the WSW social bank, which has provided €6bn to underwrite government-backed 40-year loans to housing associations. These then charge tenants the same amount they had previously paid for rent and energy bills together, until the debt is repaid.
The prefabricated refurbishments come with a 40-year builders’ guarantee that covers the entire loan period, and a 5.25% return is guaranteed to participating housing associations.”
Guardian Today: the headlines, the analysis, the debate – sent direct to you
theguardian.com/environment/2014/oct/10/uk-looks-to-dutch-model-to-make-100000-homes-carbon-neutral-by-2020

This report touches on one of the main problems for homeowners and that is getting honest and unbiased advice on what to do. The other problem is the consequent servicing.
energypoint.bearingpoint.com/blog/2015/09/24/european-home-energy-efficient-renovations-market-a-belgian-dutch-french-german-and-uk-case-study/

This covers that dreaded question of how air-tight should one be. I am a fan of heat-exchanging ventilation that doe not seem to feature in this work:
bmjopen.bmj.com/content/5/4/e007298

Profile photo of PatrickTaylor
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solar-trade.org.uk/wp-content/uploads/2016/05/Solar-storage-Opportunities-The-STAs-Position-Paper-on-Energy-Storage.pdf

In passing it knows that electric cars have substantial battery storage capacity. I recall that a year or two ago the auto industry was suggesting electric cars with the ability to provide energy back to a house if required. Sounds good doesn’t it.

Profile photo of wavechange
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It’s high time that all new buildings were built with a solar roof and oriented to make best use of the sun. Add-on solar panels are not exactly attractive. When I moved home last year I bought a house with the rear of the roof facing the right direction, so that panels would not be seen from the front. Unfortunately, not a single house nearby has solar panels. We are outside the local conservation area, but maybe there are local rules.

Since 1980 I have spent time living off-grid when on holiday, dependent on batteries overnight, and charged during the day. I first met solar panels in the early 90s when they were extremely expensive and less efficient than they are today. Solar panels are silent and once installed there is no running cost, unlike using a generator.

Knowing that you are dependent on limited battery capacity encourages conservation of electricity and this awareness has helped me become a low energy user when living in my home. If you are not using electricity for any heating other than brief use of a microwave oven and you have low energy lighting and no wasteful electrical products like plasma TVs, modest battery capacity is adequate to be independent of mains electricity for most of the year.

I’m interested in solar power and battery storage and will try to find out why none of my neighbours has solar panels.

Member
Patrick Taylor says:
8 May 2017

theguardian.com/sustainable-business/2017/may/04/solar-renewables-energy-thin-film-technology-perovskite-cells

The everchanging market always tempts one to wait, in this case to the end of the year might be worthwhile.

“Oxford PV, a spin-off from researchers at Oxford University, announced two large investments (£8.1m and £8.7m) in late 2016 from investors including Statoil Energy Ventures and Legal & General Capital. The company has also announced it is partnering with an unnamed major global solar manufacturer and intends to bring a product to market by the end of next year.”

Profile photo of Ian
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We considered the idea – briefly – some years ago. A stack of 24v lead-acid batteries (know any old submarines being scrapped?) with an inverter strapped on and then the only bit you need an expert for is the connection to the house mains – or not, if you’re feeling brave.

We do have UIPSs in the house, powering all the computing equipment to forestall the damage incurred during power cuts (yes – they happen up here) and they’re lead-acid. But the capital outlay for the battery stack would be in the £4-500 mark, the inverter another £200 and then the cost of patching them in. We have a stream running across the bottom of the garden so I suppose we could make our own mini-hydro system.

Profile photo of wavechange
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Lead-acid batteries are the traditional way of storing electricity but there are disadvantages other than the weight. To have a reasonable working life it’s best not to discharge them more than 50% of their capacity on a regular basis and leaving them in a discharged condition for any length of time is likely to ruin them – as many caravan owners have discovered. Lithium batteries, such as those used in phones, computers, modern power tools and electric vehicles, are a much better solution and gradually becoming more affordable. Within reason, it does not really matter how they are used. Some of the inverters on sale are poorly built and unreliable, but a good inverter that is conservatively rated should last many years.

Member
Phil says:
13 May 2017

Lithium batteries don’t like being left in a very high state of charge for any length of time. If you leave your Nissan Leaf parked for seven days with 100% charge you invalidate the battery guarantee. They don’t like deep discharge much either. All this means in practice is that a 5kwh battery is really only good for 4kwh.

Profile photo of wavechange
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Thanks Phil. It’s obviously vital to read the instructions. I knew that laptops protect their batteries from deep discharge but I was unaware that lithium batteries could be damaged if kept fully charged. I hope that does not apply to all types. As you say, the effective capacity is different from the stated capacity of the battery.

With lead-acid batteries and non-rechargeable ones, the capacity depends on the rate of discharge, and is significantly less with fast discharge. I would assume that the same applies with lithium batteries.

Member
Patrick Taylor says:
8 May 2017

euanmearns.com/high-altitude-wind-power-reviewed/

A fascinating look at wind power full of interesting detail. It also discusses the cheapness of the electricity meaning hydrogen as a power store.

Profile photo of wavechange
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I hope you enjoy your new home, Patrick, but I think you should ask the neighbours before storing compressed hydrogen. It could save you a bomb, or create one. 😉

Member
Robert says:
15 May 2017

Compressed hydrogen is a terrible solution: you lose at least 30% of the energy in the electrolyser, then you have to put energy into compression, which you don’t get back. And then you lose another 35-40% in the fuel cell when you convert the hydrogen back to electricity. Furthermore, the fuel cells are very expensive. Any sort of battery system does better.

Profile photo of PatrickTaylor
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On a personal level I am sure you are correct but for mass storage of large amounts of electricity that has been generated pretty much for free you can afford to be “wasteful” as the power can be stored in bulk and has multiple uses. Driving a turbine to produce electricity in bad weather, or in adapted vehicles. – and as you are burning it in both cases the conversion back factor of 35% or so is avoided.

Note the idea that gas plants may, in some countries require the subsidy. And natural gas is much dirtier than hydrogen.

“After the dramatic cost reductions of the past few years,” explained BNEF chair Michael Liebreich, “unsubsidised wind and solar can provide the lowest cost new electrical power in an increasing number of countries, even in the developing world — sometimes by a factor of two.”
“It’s a whole new world,” Liebreich said. “Instead of having to subsidise renewables, now authorities may have to subsidise natural gas plants to help them provide grid reliability.”
How cheap are renewables now? The report lists “a hectic series of milestones for declining costs” taken from actual auctions around the world in 2016:
$60 per MWh for solar in Rajasthan, India, in January
$30 per MWh for wind in Morocco, in January
$37.70 per MWh for wind in Peru, in February
$40.50 for solar in Mexico, in March
$29.90 for solar in Dubai, in May
$60 for solar in Zambia, in June
$80 for offshore wind in the Netherlands, in July
$29.10 for solar in Chile, in August
$55 for offshore wind in Denmark, in November
Note that $29.10 per MWh is 2.91 cents per kilowatt-hour. For context, the average U.S. residential price for electricity is 12 cents per kWh.
“Solar power delivers cheapest unsubsidised electricity ever, anywhere, by any technology,” Liebreich tweeted back in August regarding the price of solar in Chile, as we reported. In that same auction, the price of a new coal power plant was nearly twice as high.

globalpossibilities.org/stunning-drops-in-solar-and-wind-costs-turn-global-power-market-upside-down/

Profile photo of John Ward
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Chile must be an interesting situation. At over 2,500 miles from north to south, with the Pacific Ocean on one side and the Andes mountain range on the other, and every imaginable climate available, where do they take their solar readings?

Profile photo of John Ward
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Electricity is one of the least of our monthly expenses compared with gas, phone rentals, insurance, council tax, and other regular outlays. To spend a lot of money chiselling a marginal amount off the electricity bill doesn’t seem like the best use of our efforts. I think that, as consumers, we should be pushing as hard as possible to get the price of electricity down so that it is economical for everyone. I won’t bore readers on this occasion by repeating my mantra about the government levies on top of the energy tariffs.

Profile photo of wavechange
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One you have solar power then that makes heat pumps more affordable and then you can cut down on use of fossil fuels for heating and water heating and charging electric vehicles, though it does not help in the winter months when solar panels produce little power.

I don’t think the government’s initiatives have been right, but I do support balanced use of the various forms of renewable energy.

Profile photo of Ian
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I’ve always wondered why more isn’t done to utilise the heat produced by a conservatory. The average conservatory becomes extremely hot with only a small amount of sunshine. Instead of using that heat, we all shade it or open doors and windows. A simple heat pump could use it to heat a large amount of water – the main cost for any home.

We have two heat pumps and I can vouch for their astonishing efficiency.

Profile photo of malcolm r
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I’ve never understood the obsession with conservatories. They are generally too hot in summer, too cold in winter, and why do we need light in all directions and then stick in blinds to cut it down? Because they are cheaper than a conventional extension, I suspect, but much less comfortable. At the very least, use a lightweight insulated tiled roof, or one with water pipes to provide warm water for the house (in addition to those on the main roof perhaps).

Profile photo of wavechange
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I have never been a fan of conservatories but having inherited one when I moved house I can see some advantages. Early in the morning it can be much warmer than the house, so no need for heating. The warm air is wafted into the house, so no need for heating when the conservatory becomes too warm. With the doors to the garden open I can sit and watch and listen to the birds.

With plenty of light coming in through the windows, I wonder if there is scope for solar panels on conservatories, and then add a home battery.

Profile photo of wavechange
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Alfa posted this link in another Conversation, showing that a solar roof does not need to look like rather unsightly solar panels added to an existing roof:
http://uk.businessinsider.com/tesla-solar-roof-solar-city-features-2017-2/#tesla-will-offer-four-types-ofshingles-to-match-different-housing-aesthetics-in-an-effort-to-get-homeowners-to-ditch-clunky-solar-panel-add-ons-in-favor-of-a-beautiful-roof-1

Just the job for new homes and other buildings, together with batteries of course.

Member
Desmond Brown says:
9 May 2017

I have used a 3.5KW PV system for over 4 years. It just happened to fit on my garage roof facing a few degrees W of South. On a clear summer day we generate 25-30 KWh. The company suggested we would average 3000KWh per year and we have, very closely, so far. I had checked my consumption over the previous several years and it ran at 4000KWh per year.
Several observations have emerged. With the grants, it is a good financial return on the capital. As a green solution, it’s not as good as I hoped. We have retired and are very active away from home especially in summer. Hence we are not using the power we generate.The best we have managed is less than 30% over the years and that is actively running the laundry on sunny days etc. The next observation is that our power consumption has dropped about 50%, we are out a lot and the lights have been replaced with low energy bulbs and will probably go to LED on the next change. What to suggest? If you have young children and a big daily demand for electricity, you will use a bigger proportion of it than us, probably diverting the surplus to an immersion heater. If finance is tight, have a good look at low energy bulbs and devices. Switch stuff off.
It is tempting to think that with a storage system we could be independent but winters are long and dark, some winter days we make 200-300W, not enough to keep a battery charged. So I doubt if an expensive storage system is worthwhile.
At sea I have added an 80W PV system and controller to my bank of 12v batteries (semi-deep cycle) so far it has powered instruments and a fridge without having to resort to shore power or the engine but that’s a different world. If you have been reading, best wishes

Member
Patrick Taylor says:
9 May 2017

Thanks Desmond. Practical application and analysis is much appreciated.

Profile photo of JohnWest
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I cannot see that the government would want to create any incentive regarding these storage batteries since to charge a battery would be pushing less energy back into the national grid. It may reduce what one would take from the national grid but would energy companies have an interest in reducing ones bills, and as such would the government assist in this when the whole point of utility privatization was to make the rich ever richer and the poor ever poorer. (Give the peasants a few hundred quid in shares and then tell them then eat cake!)

I am approached about 3 or 4 times a year by these commission making battery sales persons. It seems they have obtained a national list by surreptitious means as to who has solar panels. They phone with all sorts of stories such as they have taken over the company who installed ones panels to sending details of the massive savings. Just lead them on and state that lithium batteries do not have marvelous safety record etc. and then hear the next chapter of their sales pitch. It is music to ones hears providing ones is not taken in, and there is nothing worth watching on ones TV.

It seems as if when one sales racket comes to an end such as double glazing another starts up such as solar panels but now they cannot sell quite many of them because of the reduction in FIT they have moved towards batteries instead.

There is another racket in the making however after these batteries. It is that your Inverter (Converts the low voltage DC from ones panels to mains voltage AC) are not that efficient and/or they can individually convert each of your panels 24 volt DC to mains thus reducing the effects of shadowing and spreads in solar panel output efficiency level etc. All very nice but if only the figures they create had a basis on scientific facts and/or represented and thus match your individual installation.

As for the green issues. Has anyone counted the total energy consumed to make these batteries, the petrol to get the salespersons and their cars & vans to your address, the energy to heat the buildings and premises they work from etc?

Member
Dick Fletcher says:
13 May 2017

Patrick Taylors link to the BRE site is most useful. Thank you.
It is a pity that Which? did not include this at the start. The Which? report is superficial and not helpful in sofaras it provide links to other authorities on the subject.

Member
Steve emsley says:
13 May 2017

I think these systems are interesting, but savings will depend on your usage. Cutting usage by using LED lighting and turning off standby, and appliances not in use will probably give a better return more cheaply at present. Most people could save more money by better home insulation . Our electricity bills are just £300 a year, and at a guess we could only save maybe £75 a year using a battery system.

If we had an electric car and used that battery as well as our solar panels, then it would be a more integrated fit, not needing a separate battery.

So I am not opposed to battery systems, but first of all reduce your use, insulate, get efficient appliances. You stand to save more as well as reducing your effect on climate change.

Member
Gordon Monk says:
13 May 2017

I have no doubt that the battery systems currently available are built to very stringent safety standards, but my concern is that once these systems become mainstream and are seen along with double glazing, large flat screen TV etc as an essential item to have in a modern household, that lower quality and ‘fake’ systems will flood the market leading to some very nasty fires. We have all been warned about the ‘fake’ mobile phone and laptop batteries and the damage that these can cause – imagine several thousand of them catching fire at the same time, and you know that it’s going to happen! I would hope therefore that the manufacture and supply of these devices is strictly regulated, but not in such a way that will discourage people from fitting good quality units, just to stop the supply of dangerous ones. Assuming that it’s viably and ecologically cost effective, I’ll probably be an ‘early adopter’ of one of these systems, but I will be making absolutely certain that it’s from a trusted source.

Member
David says:
13 May 2017

I sometimes feel Which reviews the easier items to assess, mobile phone, washing machines etc. I have several times urged them to focus more on items of growing significance to readers, flood protection, flood insurance etc. This is another example where Which are collecting “Brownie Points” by publishing an article on battery storage with absolutely no help for anyone considering such a move. Advice on available systems, calculating benefits etc would have been extremely useful.
Thanks to Patrick Taylor for a very useful link to information on battery storage.

Member
P A Turner says:
13 May 2017

There is another use for batteries; convenience and safety in a power cut. We two 80 y.o.s live in an assisted living flat, which is all electric, I believe so that a stay in place fire alarm policy is practical. Please could Which recommend a package of deep draw batteries, inverter, trickle (?) charger and 15 m extension cable that would power a TV and two LED lights until bedtime. Ideally it would cost less than £250. Normal householders might find it useful to keep their gas central heating going.

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You may like to bear in mind the BRE article actually mentions some systems do not work in the event of a power cut. Astonishing but it seems so counter-intuitive we must alert people to this , IMO, major flaw.

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P A Turner – Gas central heating systems are wired into the mains, so you cannot just plug them into an inverter. If you use batteries and an inverter there must be a switching system that ensures that the house wiring is connected to the mains or inverter (manually or automatically) but never both.

There is no problem with powering the TV and lights as you suggest.

Profile photo of wavechange
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Patrick – The BRE article makes interesting reading, though some of the information is rather misleading and looks as if it’s been written by someone with better writing skills than technical knowledge.

It is not explained why some systems do not automatically maintain a supply in event of a power cut but there may be some benefits. If you have limited battery capacity then it is vital to switch off non-essential loads as soon as possible to ensure that there is sufficient power available for essential purposes.

In the UK, most people don’t usually make provision for power cuts unless they live in rural areas where they are frequent, or power is needed for essential medical equipment, etc.

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You are quite right. I happened to inherit the simplest form of this, a SINGLE wall socket and a three pin plug which fed the old oil boiler. The reputable firm that installed gas boiler continued to use this.
P A Turner

Profile photo of wavechange
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Thanks very much. I had wondered if this is legal, but don’t see a problem since other fixed appliances such as gas hobs and cooker hoods are often plugged into mains sockets. I know that my heating draws about 110W when the gas boiler is fired and the circulating pump is on its lowest speed. I use batteries and an inverter to keep some lights on when there is a power cut.

Member
smug_alec says:
13 May 2017

So what’s new? It’s called a UPS.

Member
Graham Dawson says:
14 May 2017

Have SOLA_X battery system, 2 x 2.4KW hour. Have frequent battery cut-out, fault occurs in evening when use 3 KW kettle, a battery unit is likely to cut out, needs manual reset. Installer went out of business,am now relying on 10 year guarantee insurer who has little experience with battery system. SOLA_X will not act directly. When working very effective.

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I just don’t see the business case for a battery storage system.

I have a 3.96 kwh solar PV system that has for the last 3 years delivered an average annual output of 3,915 units.

In the summer half of the year, my meter readings show that my average daily purchase of units from the grid is 5.0 units per day; the comparative figure for the winter half of the year is 9.1 units.

Making these assumptions – as indicated by the above 2016 BRE guide:
– My solar panels would probably not generate any meaningful charge for the batteries in the winter half of the year.
– An ac-coupled lithium system has a 75% depth of discharge.
– A 4.8kwh ac lithium battery storage system would probably suit my usage pattern. http://www.eco-cute.co.uk/battery-storage-new/ gives a website quote of £3,995 for installation of this sized-system with a claimed life expectancy of 15 years.
– Allowing for holidays, such a system would reduce my meter consumption by 3.6 units per day for 170 days during the summer half of the year.
– At an assumed price of 18 pence per unit, that gives an annual cost reduction of £110.

At the price of £3,995, the projected simple break-even period is thus 36 years – well beyond the claimed life expectancy of 15 years, and never mind how long I am likely to be at my current address. Although I am in tune with the concept, viability seems a long way off.

Whilst the Which? headline obviously caught my interest, I echo the other comments that the Which? remarks are disappointingly-shallow.

For interest, my average (over 3 years) annual meter consumption before the solar panels were installed (in 2011) was 3,639 units; over the last 3 years my average annual meter consumption has been 2,404 units – thus solar panels have reduced my meter consumption (with no change in occupancy etc) by 34%. Also, my solar panels generate more units (3,915 per year) than my pre-installation meter consumption (3,639 per year).

Member
Mike Hymas says:
14 May 2017

Home battery storage has the following benefits:more generated power is used rather than exported which is a financial benefit; The demand on the grid is reduced at a peak time; electricity use can be maintained during power cuts (subject to approval). The payback can be long time-up to 10 years but this will be much less if electricity prices increase. There are therefore both benefits to the consumer and societal benefits, particularly by cutting demand at the evening peak when electricity generation is usually at its peak capacity.
Western power have a current trial which amongst other things uses smart meters and electric cars to reduce peak demands. See http://www.electricnation.org.uk/

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Nick Hartley says:
14 May 2017

I looked at battery storage to add to my 14 panel 3.6 kW solar PV system which has operated since 2011. The promise of reducing one’s electricity bills by importing less is seductive, but, for me, the figures don’t stack up. We pay around £250 p.a. to Ecotricity for 1300 kWh p.a. The panels generate about 2600 kWh p.a. and bring in FIT payment of approx £1100 p.a. So we are “quids in” though not self-sufficient. The battery system on offer (sorry, I forget the company name) cost £4000 and promised 15 years operation, so that’s £267 p.a. The saving would be 80% of our bill or £200 p.a, hence no saving.

From an overall environmental viewpoint, The Centre for Alternative Technology say it is best to continue exporting your excess PV generation to the grid, where it is used immediately and does not require inefficient battery storage (about 85% overall for Lithium batteries, including the charging and inversion). There is also the extra lifetime environmental cost to consider (mineral extraction, processing, manufacture, distribution, disposal/recycling) .

There will come a time, of course, when too much renewable energy is produced for the grid to handle at times when supply exceeds demand. Then storage will become essential. We are some way off that time still.

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“There will come a time, of course, when too much renewable energy is produced for the grid to handle at times when supply exceeds demand. Then storage will become essential. We are some way off that time still.”

I believe we already have had instances where that has happened in Scotland.

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There have certainly been several days this Spring when across the UK no coal was burned to produce electricity, the grid relying on nuclear, gas, oil and renewables. With its hydro capacity and extensive wind-power schemes Scotland is well placed to be permanently self-sufficient in electricity generation.

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We seem to focus on individual energy generation schemes which are inefficient compared to commercial-size schemes – solar panel farms for example. The same applies to storage – small capacity expensive batteries. Most electricity storage is by pumped water between reservoirs at different heights, releasing it for hydro-generation when demand exceed normal supply. However this cost a lot of money. Maybe those who are investing £000’s on relatively inefficient small home installations could be formed into a cooperative to help fund much more efficient large scale generation and storage.

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I think your calculations lead to the right answer, Nick. Investing in batteries and their maintenance at present is not an economical proposition and nor is it environmentally sound. The economics will not improve with lower FIT rates than those available to the early adopters.

With regard to your last paragraph, what you say is quite right but whether dispersed battery storage by householders will become essential is open to question. In the first place, surely, if micro-generation of solar energy and major supplies from other renewable sources can provide adequate supplies, in addition to the nuclear and other base loads, the best thing to do would be to switch out some wind turbines in order to prolong their lives and reduce the maintenance cost of transformers.

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Unless electricity is needed to provide heating (including water heating), solar panels and batteries are a perfectly viable source of electricity, at least during the summer months. Electric cars are probably not environmentally sound if you look at the overall environmental viewpoint, as Nick sensibly suggests, with the exception that they do make sense in polluted city centres.

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Nick quoted £4,000 for a set of batteries and that seems a lot to me to add to the capital costs of solar panels that might only be able to charge them over a short period each year. He also drew attention to the environmental impact of producing batteries. I agree the concept is appealing but does it really make sense?

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Value for money is not the only reason why we buy goods, John. Cars are one of the best examples. I accept that there is an environmental impact of using batteries. Traditional lead-acid batteries have a good record for recycling simply because used ones are valuable scrap. I have not seen information for lithium batteries, solar panels and associated electronics but manufacturing practices in the Far East have received adverse publicity. One of the reasons that we enjoy cheap goods in the UK is because of poor environmental standards and treatment of workers elsewhere.

I expect that home batteries will remain a niche product. My personal experience of being dependent on solar power is limited to summer holidays but they do produce a useful amount of electricity for much of the year.

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I think the world might be a better place if value for money and environmental concerns were the principal drivers of spending decisions. Cars and in-home entertainment systems are examples of goods that are acquired by affluent households on the basis of other values. For solar panels and a battery pack I doubt if status symbolism has anything to do with it and in the majority of cases the overriding objective is to save or make money with a bonus of environmental conservation on the side. Actually I am indifferent to whether batteries should be added to a solar panel installation. For some it will be a good idea and for others it won’t. This is largely a lifestyle thing: if a household is out at work all day it could make sense to harness the sun’s energy and use it overnight. For others feeding it into the grid and getting a higher pay-back than the cost of electricity on their chosen tariff might be more important.

As a matter of interest, what would be the weight and volume of a set of batteries to support a twelve-panel solar PV installation? Could the batteries be installed in the roof space? If not, the logical place is a garage or outbuilding if such is available. In many modern houses, like ours, there is no vacant roof space as bedrooms with sloping ceilings have been built on the top floor and there is no usable loft. Not that we have any intention of fitting a solar generation system because the complex gabled roof structure makes it practically impossible with the main aspects either facing in the wrong direction or blanked by the house next door.

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To establish likely value for money, consumers will need to know how long their batteries will last, so perhaps it’s better not to be an early adopter. Environmental concerns are notoriously difficult to assess, since the consumer will know little about the impacts of manufacture and subsequent disposal.

Your points about size and weight are well worth considering, John. There is not a fixed size battery bank for a certain number of solar panels. A larger bank costs more but will store more energy. Not all lofts are equal. I used to have a bungalow with masses of usable loft space but the loft of my present house seems to have been designed for contortionists and limbo dancers in mind. I can now understand why some boiler engineers refuse to install or service boilers in lofts. Even if the weight is manageable, I wonder how insurance companies would view installation of batteries in lofts in view of the fire risk.

I’m disappointed that new houses and other buildings are not built with a solar roof or even orientated to take advantage of the sun if solar panels were to be fitted subsequently. With the possibility of feeding electricity into the grid, I don’t see many people opting for batteries so long as the supply companies manage to keep up with demand. However, a repeat of the systematic power cuts of the 70s might make home batteries the next big thing.

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A stand-by generator might be the better way of dealing with power cuts. I’d prefer to see the large roofs on commercial and industrial sites used for solar cells where more economic installations and control units could be employed. Saves the eyesore of the nice roofs required by planning being spoiled. You sometimes have to wonder what the function of planning is when it is overridden. Our village has an agreed “plan” which seeks to prevent a number of things such as using, for example, appropriate materials in the restoration or construction of roofs. It did not include solar panels, but so watt…

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A proper outdoor standby generator that will start automatically and take over when the power fails is seriously expensive. Portable generators are noisy and have to be stored indoors but used outdoors – which is fun if all the lights have gone off. I’ve been repairing a Honda generator today and I hope the neighbours were at work.

It’s obviously nicer to put solar panels on commercial buildings etc. but I suspect that the owners would prefer to make use of the power for their own purposes.

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Using the power for their own purposes is what most solar panels are for, I would think. They relieve the commercial generators.

We rarely have power cuts of any length, but the one thing we miss in the winter is lack of central heating. Arranging the controls and pump to plug into a small generator, with the facility to heat a kettle and plug in a table lamp, would relieve the gloom. A torch will find the generator in the garage or shed and if you think you might annoy the neighbours, make them a hot drink.

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I have not had anything other than momentary power cuts despite having moved to an isolated development, but power cuts were quite common where I used to live. I became accustomed to using lighting powered by batteries and an inverter, or a generator for longer cuts. I did invite neighbours in for a coffee, made using a camping stove rather than an electric kettle.

PATurner has explained how to keep the heating running during a power cut.

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On the question of energy relating to Nuclear power stations the Gore-Chernomyrdin agreement ends in -2017 between the USA and Russia who has been supplying the US with nuclear fuel to power its power stations . Russian fuel provides for 10 % of electricity generated in the USA , it is taken from old Soviet missiles but the Ukraine relies 100 % on Russian fuel they stopped payment thinking Russia would be stupid enough to continue to supply -they didn’t , and were forced to pay for it again as Westinghouse Nuclear couldn’t supply it (now sold to Sweden and on the verge of bankruptcy) . The missiles are coming to an end and its down to supply the USA or Ukraine if Russia does not supply the US 40 % of the East coast nuke power generation of electricity will stop . Global enriched uranium = 40/50 thousand tons /year for the 400 nuke power stations in the world meaning a deficit of 20/30 thousand tons , who loses out ?

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andrew leng says:
16 May 2017

With all these energy storage / heating comments by Which I never see any mention of Night stores heaters. run on reduced night time tariff.
25 years ago we purchased a simple brick built barn conversion with night stores. There did not seem any sense investing in the capital cost retro fitting of another system. In 25 years our maintenance costs are virtually zero we have replaced one or two elements (in the old days this did not need an electrician) and a thermostat. No leaks. We work form home. No annual maintenance charge or boiler replacement.

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Good point, Andrew. Lots of householders have no choice other than to use night storage heaters on economy tariffs but I cannot remember ever seeing a Which? report on them.

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Hi Andrew, morning @johnward. You can find detail on storage heaters over on the Which? Reviews pages here: http://www.which.co.uk/reviews/home-heating-systems/article/home-heating-systems/storage-heaters But I take your point that we could certainly comment on them more when talking about conserving energy and saving money on utility bills.

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Thanks, Dean – but are there no storage radiator product reviews in the pipeline?

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Storage heaters running on off-peak electricity can make sense, especially if mains gas is not available and the house is occupied most of the day. Andrew makes a useful point that storage heaters are maintenance free and rarely need repairs. Even if one fails, the rest of the house will be heated whereas when a gas or oil boiler fails you will have no heating or hot water and have to rely on portable heaters and kettles of hot water until repairs are completed.

Having said that, using home batteries to run any form of heating is either impractical or would need a massive battery bank.

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andrew leng says:
17 May 2017

Yes we need considering re utility bills. I dont want to find we are the unintended consequence of the proposed cap on electricity bills and hope the off peak tariff is not somehow caught up and raised to match the limit between the discounted rate and the top rate.

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I’ve got to put my hands up, I’m a bit of an Elon Musk fanboy. I can’t wait for the day I’m overseeing the installation of solar panels on my roof (https://www.tesla.com/en_GB/blog/solar-roof) and a home battery in the garage next to my, hopefully somewhat more affordable by then, Tesla. Of course I’m a long way off being able to invest in all this energy and planet saving equipment let alone a house. But, the fact that all this technology comes from a positive place of addressing the environmental issues facing our planet means I’m more than happy to wait and dream and buy the odd energy saving light bulb in the meantime.

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andrew leng says:
17 May 2017

Yes and if like our friend your radiator goes you have to replace carpets and floors the insurance might pay but you have all the mess and builders to arrange while you are at work and possible ceiling damage too.

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Conventional radiator-based heating systems are a bit of a liability and I know many people who have suffered water damage due to their heating systems. I had contractors in recently and managed to bodge removing a radiator. They had covered carpet with sheet taped to the skirting boards but four days later discovered that the carpet was sodden and had been put in my garage. The company has agreed to replace it and it has gone in the skip. Electric heating certainly has its advantages.

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Your radiator can be removed without mess if you take care. Turn off both valves and drain it. I put in my own wet radiator system 35 years ago and had no problem removing radiators when redecorating. If your valves have failed your plumber can freeze the pipes locally to allow the rad to be removed and the valves replaced.

Electric heating is around 2 times the cost of gas to run and installing decent storage radiators with their wiring will not be cheap. remember on off-peak tariffs your on-peak units cost significantly more than a normal tariff.

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I always remove radiators for decorating and never had a problem. I presume that the contractor had forgotten to turn off one of the valves but I was not there at the time. I generally drain the system which empties radiators and makes it easy to collect the water containing corrosion inhibitor. I’m referring to an old system with a header tank rather than a pressurised system.

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Robert says:
17 May 2017

I’ve been interested in these since I first came across the idea, but not for cost purposes. We live in an area which is prone to brown-outs, and the occasional complete outage (4-5 in the last three years). Would a system like this act like a computer UPS and see us through problems, or reduce the risk of damage due to a power surge?

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Gerry Mewton says:
22 May 2017

I am frequently called by a company that is trying to persude me to have a battery to increase saving from my solar panels. I had a visit but the costings were rubbish. My electricity costs for the last 12 months were about £305. I estimate that I use about 35% of the 3000 kwh produced by the panels, say 1000kwh at 10p, £100. A battery would increase that saving but not by more than about 20%, in other words an additional £20 pa unless it had a really high capacity so it is just not worthwhile as an investment. They quoted me £4,500 all together!

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John de Rivaz says:
25 May 2017

I have a Sofar ME3000SP. This has the advantage that it doesn’t require a lot of DC re-wiring, and can even be run on a 13A plug and a couple of current transformers, one one the load and the other on your PV inverters. However if you plug it in rather than wire it in, then you need to shut it down every so often and remove and re-insert the plug. These plugs were not designed for continuous 3kW usage, and can form corroded hot spots if you don’t do this. There is a disadvantage in that the wi-fi reporting doesn’t seem to work, but this is very much a “frill” – it has its own screen where you can check it is working and report per day, week, month or year.