Solar Panel Installation Guide

Solar panel installation process

We’ve been installing solar PV since 2010 and sometimes forget how complex it can seem to newcomers. So we’ve put together this solar panel installation guide to help demystify the process and walk you through what’s involved with a variety of project types.

Here’s a brief rundown of how the process runs with Spirit:

1. The first step when you get in touch with us is to run a remote survey of your property, from which we can provide a quote and start designing the system.

2. One of our advisors then comes to site to answer any questions you may have, as well as taking measurements and inspections to finalise the quote.

3. Once the quote is accepted, one of our engineers then comes out to perform a technical and structural survey on site, which checks if everything is physically and electrically suitable for installation. Our head engineer will discuss the location of components and cable runs.

4. Providing there are no issues, domestic rooftop installations under 4kWp can proceed (the process from ordering to completion takes about 4-8 weeks). For commercial and larger domestic installations, we have to apply for prior DNO permission and/or planning permission if required (together this can take upwards of 5 months).

5. On installation day, a team of two or more installers (depending on the scale of the project) will be on site to fit the mounting system, attach the panels and connect up the electrics. The precise steps involved will obviously vary depending on whether it’s rooftop or ground mount, on-roof or integrated, the number of inverters, and if there is battery storage.

6. The installers run the final tests and commission the system.

7. Our office team later sends a handover pack with all the details and documents you need.

Assessments relating to solar PV

There are a few pre-install assessments that relate to solar PV:

• Site survey - one of our advisors comes to site, takes measurements, answers questions, and firms up the quote.
• Technical survey - our head installer comes to site, checks earthing & bonding, takes more measurements for the structural analysis, and makes final decisions on where equipment will be placed.
• DNO permission - when installing PV systems, we have to notify the distribution network operator (DNO). For small systems (under 3.63kWp on single phase/11.04kWp on three phase), this can be done retroactively. But for any larger installations, prior permission from the DNO is required. The DNO may decide that additional work needs to be done to strengthen the local grid, or adjustments must be made to the system such as a reduced size or export limitation.
• SAP requirements - Standard Assessment Procedure (SAP) is the way energy ratings are calculated for new build properties. Solar PV can help meet the carbon emissions reductions required: multiply the expected output of the system by the carbon intensity of displaced grid electricity to work out the carbon savings from installing solar.
• Building Regulations - solar panels must pass Building Regulations for structural and electrical safety. You don’t need to make your own application regarding this if your installer is MCS certified and a member of an approved Competent Persons Scheme like NICEIC. After installation, we provide certification to prove the system meets requirements.
• Planning permission - see below for when it is required.

Planning permission for solar PV

Domestic rooftop solar installations are generally considered permitted development and don’t require planning permission. Exceptions:

• Flat roof installations will require permission, as they project more than 200mm from the roof surface and/or are the highest part of the roof surface excluding the chimney.
• Listed buildings require listed building consent, as well as planning permission.
• Conservation areas require permission if panels are to be wall mounted and visible from the public highway.

Ground mounted solar PV, whether domestic or commercial, generally requires planning permission. Only very tiny installations can get away without it.

Commercial rooftop solar installations are also generally considered permitted development, so long as the system is under 50kW and panels are at least 1m from the edge of the building, and protrude from the surface less than 200mm (pitched roof or wall) or 1m (flat roof).

For more details, see our guide to solar planning permission.

Solar PV system design

When designing a solar PV system, there are a number of important factors to consider:

• Orientation - the direction the system will face (e.g. south, east/west). For existing buildings with sloping roofs, this is clearly fixed and will influence the viability of installing solar (north-facing is not worthwhile in the UK). With ground mount and flat roof systems, you may have more scope to choose the best orientation.
• Tilt - the angle of the panels to the horizontal. The optimal tilt to maximise generation varies depending on location and orientation. As with orientation, you don’t get much choice on existing sloping roofs. There are standard tilts chosen for the best compromise between generation and in-row shading for flat roofs and ground mounts.
• Shading - the enemy of solar generation. During the design stage, we run a virtual shading analysis to assess the impact of any shading from nearby roofs or trees. This will help decide where to place panels to minimise losses, and whether you’d benefit from optimisers.
• Grid connection - will the system be connected to the national grid? In the vast majority of cases, it’s better to connect to the national grid than try to go off-grid with solar PV if you can. If you try to go off-grid, you will either need to massively oversize the PV array and battery storage, or rely on a diesel generator. As stated above, grid connection requires some form of DNO permission.

Solar panel installation costs

Obviously, solar panel installation costs vary based on the size of the system, location, complexity and equipment chosen. But as a ballpark figure, PV costs about £1,600-2,200 per kWp to install, making a standard 4kWp domestic system about £7,000 (inc. VAT).

For a full price breakdown and comparison of different types of system, see our installation cost article.

What to look for in a PV installer

Your Spirit quote may not be the cheapest, but we believe it will be the best value. That’s because we specialise in high quality systems that will be with you for the long haul. As not all installers are made equal, there are some points we recommend looking out for when choosing which company you go with:

1. Are the installers MCS certified?

2. Do they provide a roof structural report?

3. Do they carry out shading analysis?

4. Which mounting systems do they use?

5. Do they use subcontractors?

6. Can they provide testimonials?

7. What kind of warranties do they offer?

More information

Our website contains a host of information on installing solar panels and every stage of the process, from design to monitoring. You may also like to download our free guide to residential PV for a concise summary: