Axle Virtual Power Plant(VPP) – Solar #14

Introduction

Axle VPP: ” Get paid to support the grid. Earn £1/kWh during grid stress periods. Keep full control of your battery while earning at least £10/month guaranteed”

Sounds like a good offer: I signed up and took advantage of their offer to also fund my GivEnergy cloud access at £5/month. When I started I had loads of questions, not least how would Axle and Wonder Watt (WW) work together, given that they would both be controlling my inverter via the cloud; would they clash?

This post covers:

• How Axle worked out in practice for me
• Wonder Watt Integration
• My results from Axle so far.
• Is this a sustainable?

Finally, a health warning: this write up is of just my experience over a few weeks, with my set up:

• GivEnergy Gen3 5kW inverter and 9.5kWh battery
• Octopus Flux Tariff (2-5am cheap rate to charge the battery, 4pm to 7pm peak rate to export from the battery)
• Wonder Watt (WW) scheduler
• Important here is that the inverter/battery has a specified maximum discharge power of 3.6kW and a maximum output [including solar] of 5kW. Ie for most Axle events, in the evening, we are limited to earning about £3 for each 1 hour event (ie 3kWh at £1/hour) assuming we are using ~500W for the house.

Please do add comments if your experience and/or set up is different.

How has Axle Worked In Practice?

First, Axle sign up was easy and it has worked pretty smoothly in “Event Only” mode. There is a tantalising option to have “fully Managed Optimisation” but this has not been open to me to select:

My cloud/premium GivEnergy service has continued without me paying. There have been some rather odd messages from GivEnergy saying that my subscription has run out, that did mean I resubscribed and paid for 1 extra month. I ignored the message when it came again, a month later, and did not resubscribe –  cloud/premium continued – phew! I think that the message is just GivEnergy’s way of saying that Axle are paying.

What about the interaction with my regular Wonder Watt Schedule? I have 7 schedules set up on WW:

This seems to be pretty robust to weather and seasonal changes – see my write up from April 2026. It is pretty close to my ‘set and forget’ ideal.

My first question was ‘how WW and Axle communications with the GivEnergy Cloud/Inverter would interact?’ This is pretty easy to understand using the browser view of the GivEnergy Cloud (Inverter>Remote Control>Remote Control History). So far none of the Axle events have been anywhere close in time to the WW charge schedule, so I will focus on discharge communications:

Wonder Watt Communications:

• Just before the schedule start (usually <1min before the start) and just before the schedule end, 5 parameters are set and then reset:

Axle Communications:

• Before the Axle event parameters are read from the Cloud/my inverter. The read process does not appear in the Remote Control History, but it is somewhere in the 30mins before the event.
• About 5mins before the event Axle sets 14 parameters:

I have not investigated thoroughly, but I think Axle does not bother writing to parameters  that are not changing, so the actual number of parameters changed does vary.

• After the event (seems to be around 15 or 20mins later) the same parameters are reset:

Do Wonder Watt and Axle Clash? Yes they can:

• Communications:
  • Eg, an Axle event starting at 7pm reads my inverter parameters while my WW schedule is discharging to get the Octopus peak rate.
  • The WW schedule will complete successfully or be cut short by the Axle event – the latter is not really a problem.
  • After the Axle event the inverter parameters will be reset by Axle to what Axle read before the Axle Event – ie the WW discharge parameters. Given that the WW discharge event end time is completed, what you see is the battery reserve limit set higher than the default 4%, Eco mode off and DC discharge enabled.
• Battery state of charge:
  • And this is a bit more obvious. If the Axle event is at 8pm (as is typical) my WW schedule will typically take the battery to under 20%, so not enough to get the most from the Axle event.

So can this be resolved? There is a manual solution. In the morning of the Axle event (Axle send a warning e-mail ~24hours ahead of the event) I manually disable some WW schedules:

This is easy enough to do and, of course, you need to remember to re-enable WW schedules for the next day. So for a typical earning of ~£3 per one-hour Axle Event is it worth doing? For me, I am interested and writing this blog and, as my granddaughter points out, I am retired and “have all the time in the world”. If I were working would I really remember/bother?…

…Good news: it looks like WW-Axle integration is on the horizon – see below.

Results so far?

Axle has worked well and reliably. On the first event, when I was learning how to manually flex my WW schedule around an Axle Event, I did have problems, but afterwards it has worked smoothly just requiring a few seconds before and after the event to disable/enable some of the WW schedules .

I have seen 8 events over around 2 months, including this evening (Fri 14th Aug) and Wed 12th, 2 hours over the Solar eclipse (I struggle to understand why the eclipse meant electricity demand/prices would rise, but the event happened!):

For each event you can drill down to see a summary of the event, including your 30min net smart meter reading and the regions taking part in the event:

I have also withdrawn money from my Axle account and it has appeared in our bank account; so the money does seem to be ‘real money’:

And at the end of June we got an account “top up” to make up the guaranteed £10/month payment.

One small point is that I have lost income from Octopus in many of these events; while Octopus do also pay me for the export when the Axle event is on, this has typically only been at the day time rate as opposed to peak rate. So the net gain is around 80p/kWh during most Axle events.

Wonder Watt Integration with Axle

Just in the nick of time for my 14th Aug-26 Axle event WW introduced an integration with Axle. This is a good start on the path to ‘set and forget’ Axle integration.

Setting up the integration is easy enough – copy a token from your Axle account to the WW settings. When this is done a new WW tab for Axle appears:

This worked well in the above event. However, there are some issues that need resolving/tidying up:

1. Looking at the Remote Control History for my inverter, Axle asked my inverter to discharge for the event, but WW just did the reset:
   • 7:53pm: Axle requests a discharge at 8pm
   • 9:00pm reset the discharge event
   • 9:05pm Axle resets the discharge event

Clearly it would be better if:

1. Just one platform did the discharge set and rest. I assume that the missing discharge set from WW is in my set up or a simple bug – I have asked for help just now. I will have another look and ask Axle how to silence their request.
2. WW was more actively preserving battery charge for the Axle event:
   • The WW integration has a first stab at this – a ‘one size fits all’ switch to turn off exports for 2hours before the event. This is a bit inflexible – 50% of my Axle events so far have been at 8pm (see above), where I have been manually disabling exports 3 hours before the event (ie at 5pm), but for the 10-30pm, 9-30pm, 9pm and 6am events a different time would be required. My suggestion would be that each WW export schedule includes an additional on/off switch so that it can be disabled in the case that an Axle Event scheduled for later in the day. I would switch this off for my 1st two schedules and on for the latter 4 schedules, so I should reliably hit the Axle event at around 60%-70% battery charge in all the examples of evening Axle events that I have seen so far
   • What about in Winter? The need to preserve battery power during the daytime (with limited solar power) becomes more important for Axle than for Octopus Flux Export (29p/kWh), so a schedule for ECO reserve battery %age (say 60% in the daytime and then back to 4% at night) would be helpful – independent of Axle events.
   • Early morning events: I have seen one 6am event so far. This relies on night time charging, so a switch in a charge schedule to be able to set a new, higher %age (independent of the weather forecast) IF an Axle event is due before, say, 12noon would help here.
   • Others may be able to propose something more elegant / suited to a wider use case/other tariffs.

Is this Sustainable?

So let us say that the Axle event process is entirely automated and remains reliable, it sounds like money for nothing? Is it too good to be true?

Axle is a venture capital funded business based on London; up to and including their July 2026 Series A funding they have raised $35.6M. They have 35 staff on LinkedIn, of whom 13 studied at Oxbridge – so a brainy bunch of people.

They say that they are working internationally to decarbonise the grid; not only controlling domestic batteries but also:

• EV chargers
• Heat Pumps
• Industrial battery installations

It looks like they are offering services to the electricity supply industry as well as domestic customers.

So domestic batteries are only a small part of their offer/plan and, perhaps, a proving ground for their technology, a stepping stone to bigger and better things, or maybe, getting into the market early while there are relatively few installs (67,000 in 2years to May 2026 domestic battery installations in the UK and a few more before that, 100,000 total?)

Electricity Whole Sale Pricing: A couple of items in the Guardian highlight the opportunity that Axle is working, in terms in wholesale electricity pricing at extremes:

• £1,400/megawatt-hour (£1.40/kWh)
• German peak electricity pricing of €545/MWh (~50p/kWh)
• Peak half-hour wholesale rates of 45p/kWh. This website shows the 16-Aug-26 Axle event as having a wholesale price of just over 30p/kWh

My Guess: I suspect that Axle is, right now, aiming to build participant numbers and prove their technology, so it is OK to run a few thousand participants at a small loss as they do this. Obviously, they cannot afford to do this forever and for ever increasing participant numbers. What might they do?

• Improve the automation so that each event produces the most kWh from the fewest number of participants (ie avoid the penalty of paying the minimum of £10/month when <£10 of electricity has been supplied).
• Reduce the £ offer to customers:
  • Stop paying the GE premium subscription
  • Reduce/stop the £10 minimum monthly payment
  • Reduce/make variable the £1/kWh offer price. My assumption is that they will make it easier to sign up and automate the event process – ultimately if this is easy enough then smaller payments for minimal effort might be more popular than the current offer.
• Increase the £s that they earn from each customer. I guess that as they build their participant numbers then the ability to significantly impact the national grid in a good way has more value. However, my knowledge of how this market operates is minimal.

I am also intrigued as to why the likes of Octopus are not doing this anyway. I guess in a small way they do with electricity events that offer Octopoints (apparently a value of 800 for £1 – I have 3,792 Octopoints – I am not too excited). Will Octopus sit around and let Axle make money from the electricity provided by their customers? They could discourage this: 

• Stick: just tell us that we cannot do it as part of their terms and conditions. I have no idea if this is legal, but in any case we can always switch to another provider!
• Carrott: make a better offer than Axle to customers (more £ and/or less friction).

Ultimately Octopus is far bigger than Axle, so perhaps they are just watching and then will move in and buy them if the business is a success?

Ultimately, many tech startups fail to make the transition to a profitable, self sustaining business and others go on to develop into something bigger (& usually different). My guess, is that, as long as Axle survive, the model will change and develop – it will be interesting to see how, and for the present I am happy to go along for the ride.

Conclusions:

Axle works. There is some easy manual intervention required to use it with Wonder Watt at present, and it looks like automation is on the way.

More broadly, there is clearly a business opportunity to make best use of the growing domestic battery resource to manage the grid and, part of this means incentivising domestic customers to invest in batteries and then invest the time to schedule the discharge. My perspective is that it is only when:

• set up and operation is so simple ‘that your granny can do it’ and
• the payback is good enough that she wants to

will the domestic user base be big enough to have significant impact.