A watchdog has warned that Britain's ageing electricity grid could add £7.8 billion a year to household and business energy bills unless urgent investment and reform are pushed through, in a stark assessment of the infrastructure challenges facing the UK's net zero ambitions. The warning, reported by The National Scot, highlights growing concern that the transmission and distribution networks built decades ago are struggling to keep pace with the scale of change now required across the energy system. As Britain moves towards greater reliance on renewable generation, electric vehicles and heat pumps, the grid is being asked to carry far more power, in far more variable patterns, than it was originally designed for. The watchdog's figures suggest that failing to address these shortcomings could see the cost passed directly onto consumers already grappling with elevated energy prices. The scale of the sum being flagged underscores just how significant the infrastructure gap has become. Grid constraints have long been blamed for delays in connecting new wind and solar projects, with developers sometimes waiting years for a connection date. These bottlenecks not only slow the pace of decarbonisation but can also force operators to switch off renewable generation when the network cannot absorb the power being produced, a costly inefficiency known as curtailment that ultimately filters through to consumer bills. For the EV charging sector, an outdated grid poses a particular headache. The rollout of charging infrastructure, both on residential streets and at motorway service stations, depends heavily on local substations and cables having sufficient capacity. Where that capacity is lacking, charge point operators face lengthy and expensive grid upgrade works before new sites can go live, slowing the expansion of the charging network at precisely the moment demand for public charging is accelerating. The warning adds to a wider debate about how the costs of modernising the network should be shared between billpayers, taxpayers and industry. Ministers and regulators have repeatedly stressed that a fit-for-purpose grid is essential if the UK is to meet its legally binding climate targets, yet the scale of investment required has raised questions about who ultimately foots the bill. Energy analysts have previously argued that without a faster and more strategic approach to grid reinforcement, the benefits of cheaper renewable generation risk being eroded by the hidden costs of an inadequate network. With the government committed to decarbonising the power sector and expanding electric vehicle uptake over the coming years, the watchdog's intervention is likely to intensify pressure on regulators and network operators to accelerate upgrade programmes. For consumers already anxious about the cost of living, the prospect of billions more being added to bills through inaction will only sharpen scrutiny of how quickly ministers can turn grid reform ambitions into delivered infrastructure on the ground.