UK Solar Installation: The 4-Week Timeline Explained

Installing solar panels on a UK home is a well-defined process, but one that involves several distinct parties: your installer, your distribution network operator (DNO), your energy supplier, and government-backed certification bodies. Understanding the sequence helps you set realistic expectations and spot any project that is moving too slowly.

Week 1: Survey, Design, and Quote

The process begins with a site survey. A reputable MCS-certified installer will visit your property to assess roof orientation, pitch, shading from chimneys or neighbouring buildings, and the condition of your existing wiring and consumer unit.

Key outputs from this stage:

• A proposed system size in kilowatt-peak (kWp)
• Roof mounting method — typically K2, Schletter, or GSE in-roof for pitched roofs
• Inverter and optional battery recommendation
• A written quote including VAT (solar installations carry 0% VAT in Great Britain through at least 2027)
• Confirmation that planning permission is not required under Permitted Development Rights (true for most pitched-roof installations)

If your property is listed or in a conservation area, you will need to apply for planning permission before proceeding, which can add four to eight weeks.

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Week 2: DNO Application and Equipment Ordering

Once you accept a quote, your installer submits a G98 or G99 application to your local DNO — such as UK Power Networks, Western Power Distribution, or SP Energy Networks. Most residential systems under 3.68 kW single-phase qualify for the faster G98 process, which is a notification rather than a full application. Systems above this threshold require G99 approval, which can take up to 45 working days in busy periods.

Simultaneously, your installer orders panels, inverters, cables, and mounting hardware. Lead times from distributors are typically five to ten working days for in-stock equipment.

What can delay this stage?

• Larger systems (above 3.68 kW) requiring G99 approval
• Three-phase supplies needing additional engineering assessments
• Equipment back-orders, particularly for battery storage

Week 3: Installation Day

A standard residential installation — typically 12 to 16 panels with a hybrid inverter — takes one to two days. The crew will:

1. Erect scaffolding (usually left for five to seven days)
2. Fix mounting rails and flashings to the roof structure
3. Clip panels to the rails and connect DC cabling
4. Install the inverter and generation meter indoors
5. Commission the system and confirm export readings

Your installer will carry out electrical checks under BS 7671 (18th Edition Wiring Regulations) and issue an Electrical Installation Certificate.

Week 4: MCS Registration, SEG, and Handover

Within 10 days of installation, your MCS-certified installer must register your system on the MCS database. You will receive an MCS Installation Certificate — keep this document; it is required to access the Smart Export Guarantee (SEG).

To register for SEG, contact your chosen supplier. Ofgem mandates that any supplier with more than 150,000 customers must offer a SEG tariff. Current headline rates (April 2026) range from 4p/kWh (Octopus Energy Outgoing Agile) up to 24p/kWh at peak times under flexible export tariffs. Fixed-rate SEG tariffs from suppliers such as OVO Energy and EDF typically sit between 5p and 7p/kWh.

Your installer will provide:

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• MCS Installation Certificate
• Electrical Installation Certificate
• Inverter commissioning report
• Monitoring app login details
• Warranty documentation for panels (usually 25-year product and performance) and inverter (usually 10-12 years)

Comparison: G98 vs G99 DNO Process