Tariff choice matters more than depot charging hardware

Energy Saving Trust's latest number-crunching is aimed at homeowners, not depots, but the underlying lesson travels: tariff structure can matter more than the kit itself. That's worth flagging for any fleet weighing solar, battery storage or on-site generation alongside depot chargepoints, where the temptation is to fixate on hardware specs and treat the electricity contract as an afterthought.

The study itself ran to over a million heat pump, technology and tariff combinations, drawing on performance data from 546 homes. It found that pairing a heat pump with a battery and solar panels can cut household energy bills by up to around £800 a year, with the right tariff alone saving up to £330 a year on heating and paying back the heat pump within two to four years (Energy Saving Trust). A typical heat pump costs around £11,700, but a £7,500 discount is available via the Boiler Upgrade Scheme or Home Energy Scotland Grant and Loan, and avoiding a failed gas boiler replacement saves roughly £3,700 - bringing the net additional cost down to about £500 (Energy Saving Trust).

Why this matters: None of those pounds-and-pence figures are fleet numbers - this is a domestic sample, not a commercial one, and anyone quoting £330 or £800 savings on a depot business case is stretching the source further than it goes. But the principle behind the headline holds regardless of scale: get the tariff wrong and the best-specified battery or solar array underperforms on paper economics. Any fleet scrutinising supplier quotes for depot electrification should ask for the tariff modelling alongside the hardware spec, not after it.