How Solar Installation Works, Step by Step

A domestic solar installation is quicker than most people expect on the day and involves more paperwork than most people realise around it. The Energy Saving Trust says a typical system takes one to two days to install. The weeks around that are spent on the survey, the design, the network operator's paperwork and, in London, often a scaffold licence.

Here is every stage, in order, and what you should receive at each one.

At a glance

1. Enquiry and survey

2. Design and quote

3. Contract and cancellation period

4. Network operator (DNO) paperwork

5. Scaffolding

6. Installation day

7. Commissioning and handover

8. Your MCS certificate and Building Regulations sign-off

9. Registering for export payments

1. Enquiry and survey

It starts with a conversation about your home, your electricity use and what you want: solar only, solar and battery, or a battery for an existing system.

Then a survey. Under the Renewable Energy Consumer Code (RECC), installers should carry out a technical site survey, where possible before you sign a contract. MCS requires the building to be assessed by a competent professional experienced in solar before an installation is designed, and the roof structure to be checked to make sure it can carry the load.

A proper survey is the most important step in the whole process. Our guide to what happens at a solar survey explains what gets checked.

2. Design and quote

From the survey comes a design and a written quote. Under the RECC code, a quote should be itemised, set out any work that is excluded and any site conditions that could add cost, include a timetable, and include a performance estimate prepared in line with the MCS standards.

That performance estimate is an estimate, not a promise. MCS requires it to carry a disclaimer saying solar performance cannot be predicted with certainty and that the figure is guidance for the first year only.

3. Contract and cancellation period

When you sign, you have the right to cancel. The RECC code gives you at least 14 days to cancel without penalty; for contracts signed at home or at a distance, that period runs from when the last of the goods is delivered. Installers must not start work during the cancellation period unless you have given express written permission, and if you do give it and then cancel, you may have to pay for work already done.

4. The DNO paperwork

Your local network operator, UK Power Networks across London, has to be told about any system that connects to the grid. Which process applies depends on size:

• G98 covers most domestic systems up to 16 amps per phase, which is 3.68 kW on a standard single-phase supply. Your installer notifies the DNO within 28 days of commissioning.

• G99 applies above that, and the DNO must be approached before installation. This takes longer and is the main reason some jobs have a longer lead time.

A battery counts towards that limit as well as the solar. Either way, the installer handles it. Our guide to DNOs and export limits covers this in more detail.

5. Scaffolding

On a London terrace, the scaffold usually has to stand on the pavement or the road. That needs a licence from the highway authority under the Highways Act 1980: the council, or Transport for London on red routes. It often also needs a parking bay suspension, which in some boroughs needs around ten working days' notice. The Energy Saving Trust notes that scaffolding may go up a few days before the installation.

If the scaffold can stand entirely on your own land, a highway licence is not needed.

6. Installation day

For a typical system the Energy Saving Trust puts the installation at one to two days. Roof work first: fixings into the rafters, rails, then panels. Then the electrical work: the inverter, any battery, isolators, and the connection into your consumer unit.

Where the battery goes is decided at survey, not on the day. It should follow fire-safety best practice, which rules out places like lofts, bedrooms and escape routes.

7. Commissioning and handover

Once everything is connected, the system is tested and switched on. You should then receive a handover pack. The RECC code lists what it should include: the signed commissioning record, certificates and guarantees, operating and maintenance instructions, a description of your system, your MCS certificate, the Building Regulations compliance certificate and your invoice.

Importantly, the RECC code says handing over these documents cannot be linked to full payment and must happen promptly after commissioning. RECC members also give a workmanship guarantee of at least two years, which transfers to a new owner if you sell.

8. Your MCS certificate and Building Regulations sign-off

After commissioning, your installer registers the system with MCS and issues your MCS certificate. MCS sets a deadline for this, and you will need the certificate to register for export payments.

Solar and electrical work also has to comply with the Building Regulations. Where your installer is registered with a competent person scheme, they self-certify the work: you receive a Building Regulations compliance certificate, and building control is notified, within 30 days of completion. You do not need to contact building control yourself.

9. Registering for export payments

To be paid for the electricity you send to the grid, you choose a Smart Export Guarantee tariff from an energy supplier. Ofgem requires the installation to be MCS certified and a smart meter that records half-hourly export. Many suppliers also ask for your DNO paperwork. Your installer provides both documents in the handover pack.

It is worth comparing export tariffs. Ofgem encourages generators to shop around, and the better rates are often tied to buying your electricity from the same supplier.

Frequently asked questions

How long does the whole process take?

The installation itself is typically one to two days. The overall lead time depends mainly on whether a G99 application is needed and how long the scaffold licence takes in your borough.

Will I be without power?

Only briefly, while the system is connected to your consumer unit.

Do I need to be at home?

Someone needs to be available for access, particularly for the electrical work indoors.

What if my roof needs work first?

Better to deal with it before the panels go on. Our guide on whether you need a new roof before solar explains why.

Request a solar quotation. We start with a proper survey and handle the DNO, the scaffold licence and the paperwork from there.