What is the Home Energy Storage trial from OVO Energy?

What is the Home Energy Storage trial from OVO Energy?
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Updated on 14/06/21 by Jess_OVO


As part of our journey to Plan Zero we’re keen to see how Home Energy Storage can help to make our homes smarter and our grid greener. As we’re in the next phase of our trials, we’re no longer looking for new participants but you can find out more about what we’re hoping to find out on our Powervault trial page or our Sonnen battery trial page.


Think of them as a large battery which can store up power you generate at home, through solar panels or other micro-generation sources. This can then be used at times when the sun goes in or when your usage peaks. What’s more the energy stored can even be fed back into the grid at times it’s needed most.


Heard about Home Energy Storage before or just discovered it and excited by it’s possibilities? Comment below, we’d love to start a Home battery conversation!


OVO member but not got a smart meter yet? - Book today!


Interested but not yet an OVO member? - Check out our plans!


76 replies

Userlevel 7
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Follow-up to what I've written above:

I have a few more details on the new Home Energy Storage unit, which I've been sent and am permitted to share on the open public forum:

Capacity: 4.2kWh to 10kWh options

Power: 5 kW continuous, 10 kW peak

Dimensions: 650mm wide x 300mm deep x 1080mm high

Weight: 96 kg -122 kg

Unlike the OVO Solar Store, this new unit is floor-mounted, not hung from a wall, and is suitable to be sited externally.

I don't know a lot more than this (yet) so please don't badger me!
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Hi @shadowfixer; I too am not in the Home Storage Trial area that's been selected. :(

However, from a technical viewpoint, OVO have made an excellent decision to work with Western Power on this. They are at the forefront of implementing the RIIO-ED1 strategy imposed on all DNOs by Ofgem.

The DNOs are required to reduce losses on the Distribution Network (below 33kV). Western Power's website has a good description of the technical losses issue and further pages stating how they are tackling it.

Modern technology like PV solar panels and Electric Vehicles connected to the 240v single-phase domestic supply are increasing network losses significantly, with some substations now exhibiting around 10%. This is unsustainable.

In a nutshell the electricity transmission and distribution networks were designed about 100 years ago, when they looked like this:

But at the start of the 21st century, this is how it now appears:

As a consequence, the phase imbalances cause transformers to overheat. And the underground feed-cables are no longer cooling down overnight because of homes charging EV's on Economy-7 tariffs.

I would suggest that WPD have chosen the specific area in Rugby for particular technical reasons. It is a town with a lot of industry, old substations, heaps of underground cables and very little in the way of commercial (3-phase) renewable energy.

It's possible that they may already be using switched-links between substations within Rugby in an attempt to share the loads. This strategy is called Network Meshing, and is based on the LV-CAP monitoring system which I have described here on the Forum in the OpenLV Topic. There are 40 LV-CAP equipped substations owned by WPD which are trialling the new Network Meshing technology.

Let's remember that we all pay a %age of our electricity bills to the DNOs. It is very much in our interest to assist Western Power in turning around the distribution losses. A decade ago they were less than 5%. If we adopt the right strategies, I see no reason why we can't get them back there again, or even lower.

OVO's Home Storage battery has great potential to reduce phase imbalance and harmonics, and hence lower the substation losses. With relevant inputs to the VCharge controlling software, the batteries can release stored charge rapidly into heavily-loaded feeds, restoring the phase balance.

Well, that's the theory. Now we need the Trial to see if it can actually work!
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Hi @rajan It's still a live project. The Storage Battery is one of three OVO products being developed by Indra Renewable Technologies. This now falls within the Kaluza Division of OVO, which is basically everything except the selling of energy to domestic customers.

With hindsight I would suggest that the Press Launch a year ago was significantly premature.

There's a whole heap more work required to allow this technology to be connected to the Grid beyond just designing a box into which you put some batteries, a charger and an inverter.

Firstly there needs to be a new G-standard for grid-connected batteries on single-phase supplies. The present three (G59, G83 and G100) all limit export to 16A.

This is OK if you want to connect a source of renewable energy to the grid, but nowhere near enough if the Storage Battery is to be used "on demand" by the Distributed Network Operator to smooth out peaks and balance phases at the sub-station:-

This graph shows the current on one feed from a substation at the end of February. Not only can you see the "peakyness" of demand, but also the imbalance between the three phases. That equals losses at the sub-station, which simply generates heat.

The advertised spec for the Storage Battery says it has an output capability of 40-45A. That's not covered by any G-standard yet available. But less than this would have little affect on the sub-station variations in demand.

Secondly, OVO need to offer a half-hour variable tariff. Without this, customers could only charge the Battery during an Economy-7 period, and release the energy during the other hours of the day. This is of no use to the DNO. They too need to be part of the variable-tariff structure, buying back electricity when required.

The Regulatory Framework is in place for this Time-Of-Use Tariff, and it is supported within the SMETS commands in Smart Meters. But it isn't yet being offered to customers.
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I've registered for my interest and have my fingers crossed with excitement I am in the trial! Currently an owner of a Nissan leaf with my partner driving a Renault Zoe. We are both enthusiastic for a greener world!
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@Transparent I run a dual inverter SolarEdge system, the 16A limit is not really a big issue anymore, the metering kit that I fitted to give the graphs above also allows export limitation if needed and is acceptable to the DNO as a means of control. It also allows me to run the immersion controller (also SolarEdge). I've attached the graph from today's immersion input, you can see its fully heated the cylinder (250 litres) very early in the day and maintains all day no problem. This is fairly typical behaviour for my system. I have a number of systems with a similar setup including one with a 5kWp input, Tesla Powerwall 1 and immersion control, that site has run grid free most of this month.

The Powerwall 1 was DC controlled battery, which is more efficient but can affect system total output, quite important for some FiT registered systems. The current trend is towards AC coupled batteries, so they effectively monitor for export energy and charge the battery with the same amount. Its basically the same as the Immersion control.

Immersion control input

5kWp solar PV with Tesla Powerwall 1 and immersion control

Userlevel 7
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Hi @Chunky; welcome to this discussion! :)

When you mention that you "currently have 9.9kwP of power" are you talking about renewable generation such as that from a solar-panel?

Although OVO haven't yet publicly announced the criteria for those taking part in the Storage Trial, I conjectured here, earlier in this thread, that it is likely to exclude those properties with an existing grid-connection for micro-generation.

That doesn't mean that OVO won't later release a version of their new Storage solution which handles solar-input. It's simply because the regulations for grid-connections currently prohibit have two sources capable of jointly exceeding 16A per phase.

Once OVO have demonstrated that their VCharge software correctly handles this technical issue, I expect the regulations to be updated with a new G-standard for grid-connected storage, including V2G (vehicle to grid).

Please request clarifications if you want them.
So, sorry just jump on the bandwagon late....

I've been playing around with low voltage applications and currently my house lighting is all 12v running from 2x leisure batteries along with all the control gear for my automation etc. Ive been using a mains charger to maintain the batteries for now, but wish to move to wind/solar and increase the battery capacity to be able to use an inverter and run some 240v for the UFH pumps.

I'm really interested in this technology and have just resigned back up to OVO for another 2 years, so how do I get started? what do I need?

The plan is to be at a point where we are off grid sufficient and if we can feed back and make a few ££ so much the better.

Back on point, The home battery technology is a really smart idea.
Only just joined OVO's forums, and delighted to find such enthusiasm for home energy storage, and V2G. But I have been watching this area on and off since having solar panels on my roof in 2011, and thought the technology is there, I'm not convinced the economics are. My rule of thumb is that the total power you can get out of a rechargable batter is the number of kW hours stored, times depth of discharge (without shortening battery life), times cycle life (for that depth of discharge). For lead acid, using 80% and 400 cycles, that is about 320 times the battery capacity. The cost per kWh is the cost per kWh of the battery divided by this metric, eg for lead acid, about £100/320, or just over 30p/hour, even if it is free to charge, and there is no difference between the charge power and the discharge power. For lithium cobalt, the number is about 0.8 x 1,000=800, for LiFePO4 about 0.8 x 2,000 = 1,600. It seems the latest Lithium NMC batteries are claiming 1,000 - 2,000 hours cycle life (but not the NCA's that Tesla use, which are still reckoned at 1000 cycles). At present, on Simple Energy Variable, with Economy 7, I pay OVO 10.038p/kWh (incl VAT) at night, and 17.493p/kWh during the day. So for every kWh stored at night and used during the day (I'm not presuming that OVO would buy my electricity during the day at the same price they sell it), I would save 7.455p. A home storage battery or V2G system has to cost less than £24/kWh (Lead Acid), £60/kWh (Lithium Cobalt or NCA), £120 (LiFePO4 or NMC - if NMC really lasts that long), or its just money down the drain. (BTW that is assuming the chargers and inverters cost nothing, or have infinite life).

The economy is a bit better if I can charge with solar power and discharge to house loads, because I always have surplus power during the day during the summer, and use power charged at daytime rates in the evening - potentially saving 17.493/kWh. However, altering the DC side of my solar system would invalidate my installation certificate and lose the FiT. If you have an electric car and are thinking of V2G, check the cost per kWh of battery before engaging with this. We're all used to mobile phone batteries dying after 3 years, but when you think about it, charging once per day, it is 365 x 3 cycles = 1095 cycles. For some time I was puzzled how Tesla owners expected 8+ years of battery life. Then it dawned on me that at 10,000 miles/year, the car only used 37 full discharges/year (Model 3 with 75kWh battery, using 270 miles EPA range). In practice, charging once per week from 20%-100% (or better practice, charging far less daily), 1,000 cycles should last about 20 years.
Userlevel 1
All registered. Already have 8kWp of solar PV, immersion control and full online monitoring. This would be a great addition, currently exporting between 10 and 20 kWh a day.
Userlevel 7
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Interesting... but I'd like to know a lot more about this product.

It doesn't seem to be derived from the Eaton XStorage, as was the OVO Home Battery product announced last year. And when I checked the twitter-feed from this morning's OVO Launch Event, there's a picture of a display saying that this new product is available in 5kWh and 10kWh versions.

That's a better than the Home Battery (4.2kWh), but still a long way short of the capacity of a typical EV (Nissan Leaf 2018 = 40kWh).

The financial viability of this is going to come down to the tariff and software controls... both of which can be altered by OVO as they learn more about customer usage.
Userlevel 7
It all looks very exciting!

Bumblebee :)

I've moved your question over here as we already had a topic and its might help others looking at this thread!

Userlevel 7
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Hi @Bumblebee,

I think there'll be lots of others asking those questions too!

There's still a lot we don't know about the functionality of OVO's new Home Energy Storage. Since it's not yet available, there are probably a number of issues they have yet to decide, such as what sort of Tariff options they will offer with it.

I've concluded that it's a different hardware design from the OVO Solar Store which was announced just 7 months ago. The main OVO site has now removed the Product pages on that Solar Store, which could mean it's being withdrawn in favour of the new model. But there's no announcement to that effect.

The new Home Energy Storage is designed mainly "in-house" by Indra Renewable Technologies, another innovative young company which OVO acquired last year (my info is from the Companies House register). Indra are credited in the slides of the Launch Event which OVO put on Twitter yesterday.

My current "best guess", based on the two EV Chargers announced at the same time, is that the Home Energy Storage unit is designed to be operated in sync with a Smart Meter. The commands to store and discharge are therefore sent via the same encrypted communications path which DCC use to read Smart Meters. Thus they are heavily protected from hacking by third-parties.

I'm hoping someone else will pick this up and confirm or deny my conjectures!

I have no idea yet whether there is any possible solar input to the model of the Home Energy Storage unit which has just been announced.
Userlevel 7
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That's excellent feedback @SparkySi!

My own solar-thermal panel clocked 141degC today too. :)

You will be unsurprised to hear that the Home Energy Storage Project Managers (PMs) are reading this thread.

What you say is very important. A typical domestic solar-PV installation is going to be 4kW due to the single-phase Grid-connection being limited to 16A (G83 Standard). So on a day like today, this would fill the largest 10Kw Home Energy Storage in 2½hrs

Remember this is a newly announced product. We don't yet know -

  • if it has a solarPV input at all
  • if it can have extra slave-units added like the Tesla Powerwall

In the meantime I think it's important that the Forum continues to generate useful feedback, like you have by providing your Generation Graph for today. Thanks.
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Hi @f0rbesy,

Interesting comments. So do you have your own PV solar panels, or is there a surfit of renewable energy available in Nottinghamshire?

I can foresee other ways in which your son can be brought up fossil-free, but I'm just trying to learn a bit more about how you expect to achieve that please.

Can I point out two matters raised by what you've written?

  1. OVO haven't (yet) told us whether the new Home Energy Storage Unit has any solar connection. Currently all we know is that it can be charged and discharged from the Mains Grid.
  2. OVO haven't given any indication that the energy in a Home Energy Storage Unit can be transferred directly to either of the new EV Chargers. It may seem logical to you & I that it does so, but the announcements thus far only declare that both a Grid-connected. There are both cost and technical considerations here.

You are first household I know of with two Leafs. Does that mean you already have two separate Chargers?

If so, what power rating are they?

The critical limitation factor here is that a standard domestic dwelling has a single-phase supply via a 100A "Board" Fuse. The four most hungry electrical circuits which you might have would be these:

  • Electric shower 45A (10½kW)
  • Cooker circuit 30A or 45A
  • EV Charger 30A (7kW)
  • Power-ring 30A

Clearly the potential to "blow" the Mains Fuse is quite high!

In future the solution will be technological. Items like the EV Charger and those which are not time-critical (eg washing machine & Freezer) will be connected via Smart Switches (ALCS). ALCS devices will communicate with the forthcoming SMETS2 Smart Meters, and are actually controlled by your Energy Supplier such as OVO.

Somehow we have to move from the present reality to the brave new Smart World. It's possible that the new OVO Home Energy Storage Unit is the missing link. It also might be a Smart (ALCS) device. But again, OVO have yet to announce that.

I'm hopeful that the Project Managers reading this will allow us to know a bit more soon. But in the meantime, I just wanted to point out that we can't infer functionality that OVO hasn't told us about!
Userlevel 1
Small correction. G83 is for maximum export energy which is 16A per phase as you say. However, with export limitation you can effectively hang as big a system as you like so long as it cannot exceed 16A for export.

The types of inverters I install have export limitation, many others are starting to offer it as a standard but not many are approved as standard but are not yet approved.

Utility scale battery stores can and are used to provide frequency response and ease demand capacity issues locally. Commercial systems are also used for power factor correction and brown/black out protection.

It makes a lot of sense for companies like OVO to distribute battery stores to homes, it is not difficult to apply to for an increased grid export level but as most battery stores discharge at a peak output of 5kW it is unlikely to be needed for domestic installations. It would be brilliant for those homes that do suffer from frequent power supply issues and allows the network to have some degree of resilience.

Tariffs could be interesting but I expect that when FiT goes next March the energy rates available to PV owners will change as that export energy starts to have more value in a stagnant PV market.

V2G is the best option for BEV owners and that would allow for a battery to be smaller to do

A bit of capacity infill when the BEV battery is low.

I expect the battery on offer will be AC connected and not reliant on PV. This is inline with almost all battery systems available now. Grid backup is a bit more interesting as it needs to be able to cope with some fairly difficult grid conditions and all automatically without risk of exporting to grid.

It’s great that OVO are doing something like this, it will almost certainly be energy companies that drive the next renewable technology phase and that’s as it should be.
Userlevel 5
I have just signed up for the trial but my understanding is that to me it’s just a box in the garage. I will have no access to any of the energy stored and no control over when it charges. I will just be being used as a storage location for testing.

My question is how often would the battery discharge into grid? I assume I will be paying to charge it and getting the money back on discharge? I guess it’s also totally possible that I do not get charged anything to charge the battery but that will mean I can definitely not use it to charge my EV until it’s out of trial and I start getting charged.

Speculation follows.

Battery charges and discharges once per day. Charge on E7/overnight discharge between 4pm and 8pm .

I expect a mix of 5kWh and 10kWh units to be trialled. (approx 50p to 100p daily cost to the triallists)

You pay for the charge and when discharging it displaces your use, so little cost or small cost advantage if on E7.

OVO get to buy less energy from the grid during peak time when prices are highest.

OVO may benefit from fast frequency response payments from the grid.

The £100 payment is a one off.

After the trial is over and all the data crunched. Units will be withdrawn, offered at a discount, left to continue operating their energy shifting at no cost to the trial members or rented to those on an E7 tariff.

I wonder how much of that speculation will come true..
My assumption is that its completely free to the trialist, no electricity costs to charge the battery and it discharges at some point back to the grid when demand needs it to. We would just be used as a remote battery storage site, nothing more. It would purely be a test to see whether the system works. For that we get a £100 gesture.

To make it worthwhile to keep, especially as you mention with E7 being phased out, we would need to have access to the battery energy (EV Charging etc) and also the ability to charge it up for lower cost (i.e. solar) much like the Tesla Powerwall battery.
Userlevel 5
More speculation/ random opinion.

FWIW I think that distributed battery storage is a game changer for the grid. What is as clear as mud is the economics of such, though I expect with the rise of intermittent renewables, battery storage will become increasingly important. May require a change in regulation to reduce the minimum amount of thermal (inertial) capacity that the grid has to provide and large scale trials such as OVO's could provide data to enable that change.

Not speculation: There is a fairly new 1GW link between Hunterston Scotland and Liverpool , another 1GW to come online later.
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I've just been told by @Darran_OVO that those of us who got accepted onto the initial Home Battery Trial last year will need to re-register our interest to be on the forthcoming Trial here.

There is no automatic transfer of details from the old database to the new.
Yep sounds spot on. I can see why OVO want us to have batteries available to them, what I don't think they've made clear to us in their marketing material/landing page, is what benefit the owner/user gets for all of this. It should be a win/win for both OVO and end users in OVO gets a nice big on-demand power source, and owners should also get the benefit of cheaper electricity by participating. However that is not yet clear.

It will certainly be interesting to see where this all goes. You've already identified the potential major pitfall in the system, in assuming everyone has smart meters, when electricity is cheap, they will all try and jump on and get it causing an unnatural spike. Sounds like they have a system to try and combat this with your reference to "intelligent randomisation". Will be interesting to see how they make access to the cheaper rates fair. I assume they will have to set HH time slots and the "random" part just offsets the start of these slots for each meter. Otherwise, if mine starts say 20 mins into a cheap HH slot, it could end up that I pay more than someone who's meter started 1 min into a cheap HH slot. Make sense? Sure they've thought about it all already 🙂
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Well, @ChrisI, I don't think the OVO Home Storage Trial is just about mechanical testing... at least, I hope not!

They should also be monitoring how the test sites change their habits according to varying tariff structures being made available. This will need to form the basis for OVO's maths gurus devising some attractive options. Otherwise no one will want to invest in static batteries, will they?!

Nor do I think the feedback should be limited to those selected for the Trial. This entire Forum Community is a very important test-bed for ideas as to how future tariff-structures might work.

I think the randomisation built into SMETS2 protocols is only a small part of what the country needs in order to:

  • balance the overall electricity grid
  • make better use of renewable sources
  • reduce overall energy demand
  • offer tariffs to assist those in fuel-poverty

The peaks of demand are not evenly spread across the country, and nor are sources of renewable power. So there will also be regional/local monitoring which will mean users in the WestCountry get offered cheaper HH-slots at different times to those in London.

The South-East is also somewhat more wasteful of electrical power. They have a higher consumption per head of population than elsewhere in the UK. So perhaps they will not care so much about using cheaper HH-slots when they're offered.

We might consider that to be fair. If they insist on using power in peak times, then they can pay more, and effectively subsidise lower costs to less wealthy areas of the country.

I expect we'll see a growth in community-owned local generation. If 1000 people own shares in some local PV-installations, then they can not only earn income from selling to the Grid, but also enjoy more cheap-rate HH-slots as a consequence! Thus there are potential benefits to those who couldn't put panels on their own roofs. They might be in a conservation area or in rented accommodation, but this will no longer restrict their ability to access cheaper power.

So there are social issues to taker into consideration as HH-slots start finding their way into tariff structures. It's not just a technical matter.
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@Kickboxingboy Nothing as of yet but hopefully we do. I am as excited as you are when it comes to being environmentally friendly 🙂
Userlevel 7
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@Kickboxingboy Nothing as of yet but hopefully we do. I am as excited as you are when it comes to being environmentally friendly :)

Same here, IT Geek 123.

I did a carbon footprint checker today and scored 43% of the UK average, feeling quite chuffed! :)

@Bumblebee Oh no way! How does one simply do a footprint checker? If you have a link, I wouldn't mind trying it out 😛
Userlevel 5
@Kickboxingboy Nothing as of yet but hopefully we do. I am as excited as you are when it comes to being environmentally friendly :)

Same here, IT Geek 123.

I did a carbon footprint checker today and scored 43% of the UK average, feeling quite chuffed! :)

@Bumblebee Oh no way! How does one simply do a footprint checker? If you have a link, I wouldn't mind trying it out :P

Here we are my friend! :)
Just got an email from OVO, slightly gutted to be honest - not in the pilot, despite being located "in the Midlands" (Warwickshire to be exact). Waited all summer with no updates, to the very last 2 days of summer (it was "Coming in Summer 2018) to find out more...

Am guessing it is because i am not in a town somewhere..... Would have been nice if they had told us the selection parameters up front....