E.ON agreed in May to acquire OVO’s energy retail business. It has not completed the purchase. The Competition and Markets Authority opened a Phase 1 inquiry on 2 September; its current decision deadline is 28 October 2026, subject to possible extension. E.ON and OVO remain separate during the review, and both say existing tariffs will be honoured.
Why the “biggest supplier” headline?
E.ON has said the proposed combination would add OVO’s customers to its own retail business. Estimates at the announcement put E.ON at roughly 5.6 million and OVO at roughly 4 million household customers, making the combined operation a potential challenger to Octopus for the top spot. That is a prospective ranking, not evidence that OVO accounts have already moved. Size alone does not tell you which supplier is cheapest for a particular Scottish postcode.
What is Octopus offering?
Octopus is expanding beyond a standard electricity tariff into a connected home system. It offers EV smart charging through Intelligent Octopus Go, solar export choices such as Outgoing and Flux, and battery control for eligible customers. Its newer Charge Pack add-on can manage a compatible home battery and advertises a minimum £12 monthly credit for participation, subject to its terms. In June it also announced its own Nook home batteries, with availability planned for 2027—not a product you can assume is installed today.
Availability matters. Octopus’s Intelligent Flux page currently contains restrictive messages about joining during volatile prices and about eligibility for customers with Octopus-installed equipment. Treat its headline benefits as conditional: confirm the exact product and battery compatibility at sign-up. Its standard Flux and other current tariffs are separate options.
What is E.ON Next doing?
E.ON Next is competing for the same flexible households. Next Optimise is a dynamic import and export tariff that can automate charging, use and export for compatible solar-battery systems. The supplier lists supported equipment, including selected GivEnergy, Fox ESS, Alpha, Sigenergy and Tesla systems; an inverter brand outside that list needs a direct eligibility check. E.ON Next is also marketing EV time-of-use tariffs and wider solar and battery packages. These are different products, so compare the full annual bill and export income rather than one attractive overnight figure.
There is a curious technology connection behind the rivalry: E.ON Next already uses Kraken, a platform developed by Octopus, for customer operations. E.ON says it would continue licensing OVO’s Kaluza platform for the OVO customer base after completion. That does not establish that OVO customers will immediately move to E.ON Next’s app or gain Next Optimise.
What does an OVO customer need to do?
Nothing because of the takeover today. OVO remains your supplier during the review; your current contract, payments and service arrangements continue. Keep your latest bill and tariff terms, especially if you have Charge Anytime, solar export or a battery offer. If you later receive a proposed change, compare it against alternatives using your own usage and postcode. There is no reason to abandon a good OVO tariff merely because a sale is pending, and there is no promise that a future E.ON tariff will automatically be better.
OVO still has its own EV charging add-on and export tariffs. Some enhanced export offers depend on OVO having installed the equipment or on keeping OVO as your import supplier, so check eligibility and what happens if you switch. For any supplier, look at the standing charge, daytime and night import prices, export rate, device compatibility, control permissions and exit terms together.
The practical lesson for solar and battery buyers
The competition should encourage more useful offers, but brand loyalty is not a savings model. Ask an installer to show a conservative estimate on a tariff available to you now and a second scenario for any smart product you can actually join. Check whether an inverter can participate before you buy it. Smart-tariff terms can change long before your panels reach the end of their life.
For a broader side-by-side starting point, see our UK solar and battery tariff guide. It should still be checked against a current supplier quote before making a decision.
Primary sources and live product pages
- CMA: E.ON / OVO merger inquiry and timetable.
- OVO: agreed sale and customer position; E.ON: acquisition announcement and Kaluza arrangement.
- Octopus: Charge Pack; Intelligent Flux availability; Nook battery announcement.
- E.ON Next: Next Optimise and compatible systems; E.ON Next and Kraken partnership.
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