Solar Glossary

DNO Application

A DNO application is the formal notification or permission request sent to your local electricity network operator before connecting a solar system to the grid.

DNO Application explained

Your DNO (Distribution Network Operator) is the company that owns and operates the electricity cables and infrastructure in your area. In the UK, there are six main DNOs (including National Grid ESO, Scottish & Southern, and UK Power Networks). Before you can connect a solar system to the grid, your installer must notify or seek permission from your DNO.

For most residential installations, the process is straightforward:

  • G98 notification: For systems up to 3.68 kW (single phase) or 11.04 kW (three phase), your installer simply notifies the DNO within 28 days of installation — no prior approval needed
  • G99 application: For larger systems, full prior approval is required. This can take 45–65 working days and may involve technical assessments

Your MCS-certified installer handles the DNO application as part of a standard installation. You should receive a copy of the G98/G99 paperwork as evidence of your grid connection compliance.

Why it matters:

  • Without DNO compliance, your installation may breach electricity supply regulations
  • It's required to register for the Smart Export Guarantee (SEG)
  • It protects your installer and you from liability in the event of a grid fault

If you're considering a system larger than 3.68 kW, factor the G99 approval timeline into your project schedule.

How this affects your solar decision

DNO approval affects your installation timeline and system size options. Use the Solar Cost Calculator to see how system size choices interact with DNO requirements.

Explore system size options and their DNO implicationsSolar Cost Calculator

Related terms

MCS CertificationMCS (Microgeneration Certification Scheme) is the UK quality standard that solar installers and products must meet for installations to qualify for government incentives and consumer protections.Grid-Connected SystemA grid-connected solar system is connected to the public electricity network, allowing you to draw power from the grid when solar generation is insufficient and export surplus power back to the grid.Building Regulations Part PBuilding Regulations Part P is the UK electrical safety regulation that applies to solar installations, requiring electrical work to be carried out or certified by a competent person.Permitted DevelopmentPermitted Development rights allow most UK homeowners to install solar panels without needing to apply for planning permission, as long as certain conditions are met.
Back to Solar GlossarySolar Cost Calculator