Three parties have a say in a Hertford home battery: you, your installer and UK Power Networks. Your energy supplier is not one of them. The supplier sells you electricity and may pay you for exports; the network operator owns the cables, decides what can connect to them and keeps the record of what is generating behind every meter in SG13 and SG14. A battery counts as generation, so it goes on that record.
This guide covers that side of the job: which network, which form, what it costs and what a battery will and will not do when the power goes. For where a battery fits in Hertford’s flats and terraces, see our page on battery storage in Hertford.
Which network serves Hertford
Hertford’s town centre sits in UK Power Networks’ Eastern Power Networks licence area, about 16.6 km from the nearest other licence area on UKPN’s and NESO’s boundary data. Before UK Power Networks, Hertfordshire’s cables and lines were run by Eastern Electricity. If you want to confirm your own address, the Distributor ID on your electricity bill is the quickest check: the Energy Networks Association lists 10 as Eastern England. UK Power Networks also runs a postcode area checker.
The 16 A line: G98 or G99
The rule that decides the paperwork is the Energy Networks Association’s EREC G98. Type-tested equipment up to and including 16 A per phase, which is 3.68 kW on a single-phase house, is notified to the network operator before commissioning or no later than 28 days after it. Anything above that needs a G99 application, approved before the work starts.
Two details catch people out. First, the line counts the whole system: panels and battery together, through every inverter, not the battery on its own. Second, it is lower than many people assume. A 4 kW inverter draws 17.39 A, so it is just over G98 and goes through G99. A Hertford home adding a battery to existing panels can cross the line without changing the roof at all.
How UK Power Networks handles it
Your installer makes the submission. UK Power Networks’ Smart Connect service, open only to approved installers, handles G98 and G99 forms for domestic solar PV and battery storage on houses and small businesses up to 69 kVA whose supply can take the equipment.
UK Power Networks says that if the maximum export of your installation, after any export limitation scheme, is under 5 kW, it will approve the application automatically. In June 2024 it described this as approval for up to 5 kW of solar and battery storage, against the industry standard of 3.68 kW. An export limit caps what leaves the house rather than what the inverter can do, which is how a larger system can stay inside that automatic route. UK Power Networks also says there will be no costs for you to pay it unless its teams need to upgrade your supply; where they do, cost and timing vary by project.
Chargers sit in the same process. DVLA records 5,327 privately kept plug-in vehicles across East Hertfordshire at the end of June 2026, up from 3,882 a year earlier, and every new home chargepoint is notified to the network by the installer, so a battery and a charger fitted together are planned as one load on one supply.
What Ofgem’s reliability figures show
Ofgem reports how often each licence area loses supply. For Eastern Power Networks in 2024/25 it shows about 44.6 interruptions per 100 customers and about 32.5 minutes lost per customer over the year, planned and unplanned together, against targets of 41.8 and 30.1, and down from 46.2 and 35.6 in 2023/24. The figure across all fourteen licence areas was 39.7 and 35.1. Read plainly, an average Eastern customer had fewer than one interruption a year (our arithmetic). Ofgem notes severe-weather adjustments were applied from the operators’ submissions, so treat the figures as reported, and they are licence-area averages, not Hertford’s own.
What a battery does when the grid goes
A standard grid-tied battery shuts down when the grid does, panels included, so that nothing is fed into cables that engineers may be working on. An ordinary system in Bengeo, Sele or Kingsmead therefore goes dark with its neighbours, however full the battery is.
Backup is a design choice made at the start. It needs switching equipment beside the meter that separates the home from the network, and a short list of circuits it keeps running, such as the fridge, lighting and broadband. In Hertford two local factors shape it. Flats are the largest single group of homes in the built-up area, 30.5% of households at Census 2021, and in a flat the extra equipment needs the freeholder’s agreement as well as the battery. And in the conservation area, first designated in 1967, or on one of East Herts’ approximately 4,000 listed buildings, that equipment belongs indoors with the battery.
Is backup worth paying for?
That depends on what a short cut would cost you, not on the network’s averages. Home working, medical equipment or a freezer full of food can make a few backed-up circuits worthwhile; for many households the everyday case for a battery is shifting cheaper or solar electricity into the evening, and backup is an optional extra. Size the everyday battery first, as our guide on what size home battery you need explains, and treat backup as a separate line on the quote. PVGIS puts a 4 kWp south-facing Hertford roof at about 479 kWh in June but about 140 kWh in December, so in winter a battery’s stored charge often comes from an off-peak tariff rather than the roof.
We are a NAPIT member (73495), MCS-certified for solar PV and battery storage through NAPIT. The roof side is on our page for solar panels in Hertford, and the county picture on our Hertfordshire solar page.
Sources: UK Power Networks Open Data, licence boundaries (December 2024); NESO, GB DNO licence areas (May 2024); UK Power Networks, Smart Connect, Solar and storage: cost, time and what’s involved, Our history, and news release of 10 June 2024; Energy Networks Association, EREC G98 Issue 2 (10 March 2025) and Find my network operator; Ofgem, RIIO-2 Electricity Distribution annual report 2024 to 2025 and supplementary datafile (15 January 2026); DfT and DVLA, VEH0142, private keepers, East Hertfordshire (published 23 September 2026); ONS, Towns and cities, characteristics of built-up areas: Census 2021 (table 5c); East Herts Council, Hertford Conservation Area Appraisal and Management Plan (adopted 1 March 2017); European Commission JRC, PVGIS 5.3, PVGIS-SARAH3 2005–2023 (run 15 October 2026).