DNO Approval: What is it and how does it work?

You must get DNO approval to export energy to the national grid. Find out what it is, how it works, and why there is such a long wait time.

What is DNO Approval?

DNO stands for Distribution Network Operator - the company responsible for the electricity network in your area. Before connecting any generation equipment (like solar panels) to the grid, you must notify or get approval from your DNO. This ensures the network can safely handle your exported electricity.

Why is it Required?

The electricity grid was designed for one-way flow - from power stations to homes. Solar panels reverse this flow, and DNOs need to:

• Ensure network stability
• Prevent overloading
• Maintain power quality
• Protect engineers working on lines
• Plan future network capacity

G98 vs G99: Understanding the Difference

G98 (Notification Process)

For smaller systems:
• System size: Up to 3.68kW per phase (11kW three-phase)
• Process: Notification only - install then notify
• Timeline: Notify within 28 days of commissioning
• Response: Usually automatic acceptance
• Cost: Free

G99 (Application Process)

For larger systems:
• System size: Above 3.68kW per phase
• Process: Apply before installation
• Timeline: 45-90 working days typically
• Response: May require network studies
• Cost: Free application, studies may cost

The DNO Application Process

Step 1: Determine Your Requirements

• Check system size (AC output)
• Identify your DNO region
• Decide G98 or G99 route
• Gather system information

Step 2: G98 Notification Process

• Install system with MCS installer
• Complete commissioning tests
• Submit G98 form online or post
• Receive acknowledgment from DNO
• Start exporting immediately

Step 3: G99 Application Process

• Submit application before installation
• DNO reviews network capacity
• Possible network study if concerns
• Receive offer with any conditions
• Accept offer and pay any costs
• Install system once approved
• Final commissioning witnessed by DNO

UK Distribution Network Operators

England and Wales DNOs

• UK Power Networks: London, South East, East
• Western Power Distribution: Midlands, South West, Wales
• Northern Powergrid: Yorkshire, North East
• Electricity North West: North West England
• Scottish Power Energy Networks: Merseyside, North Wales
• SSE Networks: Central Southern England

Finding Your DNO

• Check your electricity bill
• Use Energy Networks Association website
• Ask your installer
• Call 105 (power cut number)

Why the Long Wait Times?

Current Challenges

DNOs face unprecedented demand:
• Solar installations up 50% year-on-year
• Limited staff for assessments
• Aging infrastructure needing upgrades
• Complex calculations for each area
• Regulatory requirements adding steps

Network Constraints

Some areas experience:
• Voltage rise issues
• Thermal overloading
• Reverse power flow problems
• Protection system conflicts
• Harmonic distortion

What Happens During Assessment?

Network Studies Include

• Voltage level analysis: Can network handle export?
• Thermal capacity: Will cables overheat?
• Fault level assessment: Protection systems impact
• Power quality: Harmonic and flicker analysis
• Geographic clustering: Other local generation

Possible Outcomes

• Unconditional approval: Proceed with installation
• Conditional approval: With export limits
• Approval with costs: Network reinforcement needed
• Temporary refusal: Until upgrades complete
• Alternative connection: Different connection point

Export Limitation Devices

When Required

DNOs may mandate export limiting if:
• Network constraints exist
• Conditional approval granted
• Cost-effective alternative to upgrades
• Temporary measure planned

How They Work

• G100 certified devices required
• Dynamically limit export power
• Allow full self-consumption
• Typical limits: 3.68kW or zero export
• Can be adjusted when network upgraded

Costs and Timescales

Typical Timescales

• G98 notification: Immediate installation
• G99 simple: 6-8 weeks
• G99 with study: 12-16 weeks
• Complex cases: Up to 6 months
• Appeals process: Additional 3 months

Potential Costs

• Application: Free
• Basic studies: Free
• Detailed studies: £500-£2,000
• Network reinforcement: £1,000-£50,000+
• Alternative connection: Variable

Common Issues and Solutions

Application Delays

If experiencing delays:
• Chase regularly: Weekly contact
• Escalate: To DNO managers
• Complain formally: If exceeding timescales
• Contact Ofgem: For regulatory breach
• Consider alternatives: Export limitation

Rejection Reasons

Common issues:
• Incomplete application forms
• Wrong system details provided
• Missing electrical diagrams
• Incorrect DNO region
• Previous applications not closed

Battery Storage Considerations

Additional Complexity

Batteries add requirements:
• Must declare storage capacity
• AC or DC coupled differences
• Charge/discharge rates considered
• Grid charging capabilities
• Emergency backup features

G100 Compliance

For export limitation:
• Batteries must be included
• Integrated control required
• Failsafe operation essential
• Regular testing needed

Future Developments

Smart Grid Evolution

Coming improvements:
• Dynamic export agreements
• Real-time network management
• Flexible connections
• Market-based solutions
• Automated applications

Regulatory Changes

Expected updates:
• Streamlined processes
• Shorter timescales
• Digital applications only
• Standardized national approach
• Reduced bureaucracy

Tips for Smooth Approval

Do's

• ✅ Use experienced installers
• ✅ Submit complete applications
• ✅ Provide accurate information
• ✅ Respond quickly to queries
• ✅ Keep records of everything

Don'ts

• ❌ Install before G99 approval
• ❌ Modify system after application
• ❌ Submit multiple applications
• ❌ Provide incorrect details
• ❌ Ignore DNO communications

Working with Your Installer

Installer Responsibilities

Good installers will:
• Handle all DNO paperwork
• Advise on requirements
• Track application progress
• Manage any issues
• Ensure compliance

Your Responsibilities

• Provide accurate information
• Sign forms promptly
• Pay any required fees
• Inform of any changes
• Keep documentation safe

The Witness Test Process

For Larger Systems

G99 installations may require:
• DNO engineer attendance
• Commissioning tests witnessed
• Protection settings verified
• Export limitation checked
• Final approval granted

Preparation Required

• System fully installed
• All tests completed
• Documentation ready
• Safe access provided
• Installer present

Alternative Solutions

If DNO Approval Difficult

Consider:
• Smaller system: Stay under G98 limits
• Export limitation: Accept constraints
• Battery storage: Increase self-consumption
• Phased installation: Start small
• Different property: If multiple owned

Case Studies

Successful G99 Application

Manchester homeowner:
• 6kW system proposed
• Initial concerns raised
• Export limitation accepted
• Approved in 8 weeks
• Full export allowed after 1 year

Complex Network Reinforcement

Rural Scottish property:
• 10kW system planned
• Weak network identified
• £15,000 upgrade quoted
• Negotiated 50% contribution
• System operational after 6 months

Conclusion

DNO approval is a crucial but sometimes frustrating part of the solar installation process. Understanding the requirements, timescales, and potential challenges helps set realistic expectations. While wait times can be long, especially for G99 applications, the process ensures safe and stable operation of the electricity network as renewable generation grows.

Working with experienced installers like CRG Direct significantly smooths the DNO approval process. We handle all applications, track progress, and manage any issues that arise. Our expertise with local DNOs and understanding of their requirements helps minimize delays and maximize your chances of straightforward approval.

Don't let DNO approval concerns delay your solar plans - contact us today for expert guidance through the entire process.