When does a battery storage installation require a G99 application instead of G98?

G98 applies to systems with a total export capacity below 3.68kW per phase, covering most domestic battery installations. Larger commercial systems or those capable of exporting at higher capacity require a G99 application, which needs DNO approval before installation can proceed. The installer must confirm which applies during the site survey.

What qualifications does a battery storage installer need in the UK?

Installers need the City and Guilds 2923 Energy Storage Systems qualification plus a current 18th Edition BS 7671 certificate - with Amendment 4 Chapter 57 requirements mandatory from October 2026. To issue an MCS certificate, the installer must hold MCS 023 certification and be registered with NICEIC or NAPIT under Part P of the Building Regulations.

Can a battery storage system be quoted and installed without a physical site survey?

No reputable installer should quote or proceed without a physical site survey. The survey confirms the consumer unit has capacity for the additional load, identifies safe cable routes, and verifies a ventilated location meeting PAS 63100 fire requirements. Installing without one risks voiding the manufacturer warranty and creating fire safety issues.

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Workflow Scenario

Renewables - Battery Storage Survey to Commissioning

Survey to certificate. Every step tracked.

Step by step

Enquiry and Load AnalysisLeads

The customer enquiry is captured and their current energy usage and any existing solar PV setup are recorded. A desktop load analysis determines the appropriate battery capacity before a site visit is booked.

Physical Site SurveyJobs

A surveyor visits the site to inspect the consumer unit, earthing arrangement, available space for the battery unit, cable routing options, and compliance with PAS 63100 ventilation requirements.

DNO Application and QuoteQuotes

A G98 notification or G99 application is submitted to the Distribution Network Operator. A fixed, itemized quote is issued covering all equipment and installation labor based on the surveyed specification.

Equipment ProcurementPurchase Orders

On quote acceptance, purchase orders are raised for the battery unit, inverter, isolators, cabling, and mounting hardware from the relevant suppliers.

Delivery VerificationDelivery Notes

Equipment is received and checked against the delivery note before the installation date. Any shortages or incorrect items are flagged to the supplier before the installation crew is scheduled.

InstallationJobs

The battery unit is mounted and cabling is run to the consumer unit. Isolator switches are fitted and the system is connected in line with BS 7671 Chapter 57 requirements and PAS 63100 fire clearance rules.

Commissioning and TestingJobs

The battery management system is powered up, inverter settings are configured, grid communication and any solar PV integration are verified, and all protective devices are tested.

Certification and HandovereForms App

The MCS certificate and Building Regulations compliance paperwork are completed. The customer is walked through the monitoring app, sign-off is obtained, and the final invoice is raised.

What this workflow solves

DNO applications and MCS paperwork slip through the cracks when installation crews are juggling several jobs at once - and without an MCS certificate the customer can't access smart tariffs or export payments.

Equipment arrives on site before DNO permission comes back, which means the installation can't be completed and the crew has to make an expensive return visit.

Commissioning sign-off happens verbally on site and months later there's no record of what was tested, what settings were configured, or what the customer was shown at handover.

Frequently asked questions

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