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Understanding DNO Applications and Their Significance

When you embark on the journey of installing solar panels or any energy-generating equipment that will be linked to the National Grid, you’re required to inform your local Distribution Network Operator (DNO). This protocol applies whether you’re a homeowner or managing a business, as it’s crucial for accurate electricity assessment. The process involves submitting a DNO application to your relevant distribution network operator, ensuring that the electricity consumption can be effectively managed.

The scope of your energy system determines the kind of DNO application you’ll need, and whether it should be carried out prior to or after the installation. As a general rule, larger systems necessitate more comprehensive documentation. However, at Cambridge Roofers, we’ve streamlined the process with our dedicated in-house green team, making DNO applications less intimidating.


DNO is an acronym that stands for Distribution Network Operator. These licensed entities are responsible for the distribution of electricity from the National Grid to individual homes and businesses. In the UK, there are 14 distinct district networks, each belonging to one of 6 major groups:

  • Electricity North West Limited (ENWL)
  • Northern Powergrid
  • Scottish and Southern Energy (SEE)
  • ScottishPower Energy Networks (SPEN)
  • UK Power Networks (UKPN)
  • Western Power Distribution (WPD)

Locating Your DNO

To find out which Distribution Network Operator covers your area, a quick visit to the Electricity Network Association’s (ENA) website and the input of your postcode will do the trick. With our extensive experience in solar panel installations nationwide, we’re well-versed with all 14 DNOs.

When to Engage in a DNO Application

Any substantial modifications to your power connection require notifying your local DNO provider. This encompasses the installation of green energy technologies such as:

  • Solar photovoltaic (PV) Panels
  • Heat pumps
  • EV Charging Points
  • Battery Storage with backup/islanding functionality

Navigating DNO Permission

Unless your intention is to set up an off-grid system, obtaining DNO permission is an indispensable step. Given that your installation establishes a direct connection to the grid, compliance with local grid regulations is non-negotiable. Particularly in the context of the UK’s Net Zero push, the prevalence of electric-powered devices like EVs and heat pumps necessitates close coordination with your local DNO. This collaboration ensures that the heightened load on the National Grid is effectively managed, preventing localized disruptions and maintaining optimal supply in your area.

Unveiling the Importance of a DNO Certificate for Solar Panels

Installing solar panels without securing a DNO certificate renders you ineligible for Smart Export Guarantee (SEG) payments from the National Grid. This incentive is a critical advantage for grid-connected systems.

Diverse Facets of DNO Applications for Solar Panels

The size of your solar PV system governs the specific DNO application required. It’s important to note that system size is determined by the AC inverter rating rather than the peak DC rating of the panels. The primary categories of DNO applications are classified as “connect and notify” or “apply to connect.”

DNO G98 Applications

For small-scale Distributed Generation (DG) setups, involving a certified solar PV installer like Cambridge Roofers is pivotal. These setups operate under a capacity of 16A per phase, equivalent to 3.68kWp for single-phase or 11.04kWp for three-phase supply. If any uncertainty arises, consulting your solar panel installer is recommended. Assuming your electricity supply accommodates the added load, the installation can proceed without prior DNO permission. Nonetheless, notifying your DNO within 28 days of commissioning remains essential.

DNO G99 Applications

In the case of large-scale solar systems surpassing 16A per phase, obtaining DNO approval prior to installation is mandatory. This procedure allows the grid to thoroughly evaluate the viability of accommodating the additional load. The duration of this DNO review spans 8 to 12 weeks. Should you be installing Distributed Generation equipment rated at or above 50kW, completion of a Standard Application Form (SAF) is requisite.

DNO G100 Applications

In scenarios where your G99 application mandates export limitation, initiating a G100 application becomes imperative. This step incurs additional costs ranging from £300 to £700. Furthermore, it elongates the lead and installation time since an auxiliary device needs to be incorporated alongside your system.

Assessing DNO Application Outcomes

Upon evaluating your DNO application, you’ll typically receive a connection offer outlining specifications and any associated charges. The potential outcomes encompass three possibilities:

  • Acceptance without supplementary charges, enabling you to proceed with the installation as planned.
  • Capping of the system size through an imposed kWp AC rating alongside export limitation. This could involve a nominal fee for a witness test, confirming the limitation’s implementation.
  • Upgrading your supply size from single-phase to three-phase, enabling the solar panel installation. This modification, however, might incur a substantial additional cost contingent on the site’s requirements.

Unraveling DNO Application Costs

While G98 applications are cost-free, administrative fees from solar panel installers might apply for processing. On the other hand, G99 and G100 applications are accompanied by costs ranging between £300 and £750 each.

Understanding DNO Application Duration

The burgeoning demand for locally generated energy has prolonged DNO processing times. A G98 application for solar panels typically spans 3 months. In contrast, a G99 application, initially projected at 8-12 weeks, now experiences delays of 4-6 months due to heightened demand.

Relying on Expert Solar Panel Installers

The intricacies of DNO applications can be seamlessly navigated by choosing an experienced team like Cambridge Roofers, proficient in DNO processes for solar panels. For UK homeowners and business proprietors contemplating solar panel, battery, or EV charger installations, connecting with our green team at 01322 479369 guarantees award-winning service. Rest assured, all DNO applications are integral to our comprehensive solar packages, forming an integral part of our nationwide service. Don’t hesitate to reach out for more information on solar panels or related installations.

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Cambridge Roofers provides and installs metal roofing solutions and systems to refurbishment and new build projects throughout Cambridgeshire and London. With a dedication to quality and continuous improvement, Cambridge Roofers Ltd are able to provide only the products available in the industry through constant research and development. 

As approved installers, our warranties can go up to 40 years with manufacturers endorsement.

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