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Solar Panels

Solar PV Installation

By Sarah Ingrams

Article 4 of 7

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Solar PV Installation

We've filmed an installation of solar photovoltaic panels so you can see what to expect. Plus, find out whether your property is suitable for solar panels.

Considering buying solar panels? Watch our video to find out what happens when solar panels are installed, and learn whether your home is suitable for solar.

The picture above shows a Which? member's roof undergoing installation of a 3.5kWp solar PV system. Keep reading to find out all you need to know about solar panel installation and download our free solar PV installation checklist.

Make sure you buy good quality solar panels – see our solar panel reviews.

Installing solar panels

If the solar panels are being installed on your roof, you're probably going to need scaffolding. Make sure you check with the surveyor that there is space to install scaffolding and that the cost is included in your quote. 

Once the scaffolding is up, solar panels can be installed in less than a day.

Once the scaffolding is up, the panels could be installed in less than a day. Roofers will attach the fixing brackets on to the rafters of your roof – this is why a proper surveyor should go into your loft to check the integrity of the roof and the rafters. The solar panels will then be clamped on to the fixing brackets.

Video guide: solar PV installation

To get a better idea of what you can expect when installing solar PV, watch our video below to see a solar panel installation (on a concrete tiled roof) from start to finish, and find out what's involved.


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Video transcript

Are you thinking about installing solar PV panels? Producing your own electricity from solar is not only great for the environment, but it can also save money in the long term thanks to the feed-in tariff, and it can protect you from rising electricity bills.

But the decision
to install solar PV panels on your home is a big one.

It can be nerve-wracking when you've never seen how it's done. So we filmed a solar panel installation to show you what happens, and answer some of those common questions. But first, let's find out how the system works.

Solar photovoltaic panels generate electricity whenever it's light. Light energy from the sun hits the photovoltaic cells on the solar panel and is transformed into electricity. Conducting wires carry the electrical current from the panels to the inverter and then into your home. When it's light and you turn on your electrical appliances, they will be powered by electricity you are generating.

Any excess electricity will be exported to the national grid. If you turn on your appliances when your panels aren't producing electricity, you'll use electricity from the grid as usual. 

Before the installation process can
begin, you will have to arrange a survey with a reputable solar panel installation company.

And the number of panels that you put on your roof depends on a number of factors: the size of your roof, the direction in which it faces, the amount of electricity that you wish to generate and how much you wish to spend. 

The installation will be done in stages.
The whole process can take as little as one day, depending on the size of the system.

We caught up with solar panel installation company manager Guy Hewitt to see an installation in process. He explained: 'The process is quite straightforward actually. Before we get to the site we would have already surveyed it, so we'll have produced a detailed plan of what we're going to do on the roof.

The next phase is to mark up and set out the array on the roof, then we'll begin lifting tiles, finding the rafters and setting out where we actually are going to insert the roof hooks into the roof. 

'To install the roof hooks,
we lift up the tile, find the rafters, then insert the roof hook into the rafter - the tile is then set back down and weathered if necessary. We continue all the way along the roof to create, if you like, parallel lines of roof hooks. After that the rails are bolted onto the roof hooks, and when they're fully secured and in position the panels can be installed onto the rails.

The vast majority of roofs in the UK are able to take solar panels. Of course they need to face the right way - we wouldn't be installing solar panels on a north-facing roof. We're really looking for somewhere from east to west or south of that.

'One of the concerns a lot of people have is that there's a possibility that installing solar panels could actually damage the roof. This is not the case. Provided the right roof bolt is used for the type of tile that's on the building, and the roofers have done a professional job, then the roof will be weatherproofed.'

In the house, the direct current from the solar panels comes in through a cable and goes into an inverter box, which converts the direct current to alternating current, which is safer for your home.

And there are two isolator switches - a direct current isolator switch and an alternating current isolator switch - as safety measures. From here, the power is passed around the house. The generation meter indicates how much power your solar panels have created. 

As long as there is enough light,
the panels will start producing electricity immediately.

So, if you're interested in installing solar PV panels, go to which.co.uk/solar to read our solar panel guide and see our checklist for things to watch our for during your installation.


Is my home suitable for solar PV panels?

Solar PV panels are worth considering if you have a mainly south-facing roof with little or no shade and you're not thinking of moving home in the near future.

ideal house for solar panels

Maximum power output from solar panels will be achieved for a south-facing roof with a tilt angle of 30 degrees and no shade

Although a south-facing roof would yield the best power output, a southwest or southeast-facing roof should also be fine, but you would get less power out of the system, and therefore be able to save less on your electricity bill.

How much energy you could produce with solar panels – and therefore how much money you could make – will depend on:

  • the tilt angle of your roof and its orientation
  • where you live: the South West gets more sun than the North, for instance, and this could affect the amount of electricity your system will generate, although not too significantly.

Can you make money from solar panels? Find out if solar PV is a good investment.

What is the best roof orientation for solar panels?

The table below shows the percentage of the maximum output you will get from a solar PV system, depending on your roof orientation (west, south, east) and tilt angle (source: the Energy Saving Trust). 

Most UK roofs are angled at between 30 degrees and 45 degrees. Solar PV panels are not recommended for roofs that face north.


You also need to consider both the age of your roof and how strong it is, as PV panels are heavy. 

Solar PV systems are most efficient if you use the electricity they produce during the day. So if you work all day, leaving your home empty, you may not reap the full benefits of your solar panels. 

Shade could be a big problem for solar panels, so no panels should be installed where there is shade from trees, chimneys, walls or other obstructions. Do consider whether nearby trees are likely to grow and overshadow your roof. 

We've spoken to solar panel experts and solar panel owners to get their top tips to make the most of your solar panels.

What size of solar PV system is right for my home?

The right size for your home will mainly depend on the roof space available and how much electricity you use. We recommend that you don't buy too large a system, as you can't meet 100% of your demand with solar PV. 

Make sure the surveyor understands your electricity usage so you get the right-sized system for your needs and budget. As a guide, an average 4kWp system would cost between £5,000 and £8,000.

Before you install solar PV, read our tips and advice on what you should do and the questions you need to ask a solar PV installer. See our free downloadable and printable solar PV installation checklist.

Do I need planning permission for solar PV?

Contact your council to see whether you need to apply for planning permission for your solar panels. You won’t need planning permission for most domestic solar panels, as long as they're below a certain size. 

However, exceptions apply for listed buildings, buildings in conservation areas and World Heritage Sites. 

Do solar panels need cleaning?

Solar PV panels are self-cleaning when installed on an ideal roof slope, so should either never or only rarely need cleaning. But if your roof has a fairly shallow pitch or is flat, it may accumulate bird droppings, leaves or dirt, which will need occasional cleaning.

Are there other solar maintenance or ongoing costs to consider?

Solar panels are pretty much maintenance-free and should last for at least 25 years. 

Solar PV systems are relatively simple and have no moving parts, so they don't need much maintenance. However, within 25 years, you’ll need to replace the inverter, which costs about £1,000 (but be aware that some installers say it costs less). 

Once you’ve had solar panels installed, your installer should give you written details of any maintenance checks you need to carry out occasionally to check your system is working properly.

How can I find a reputable solar panel installation company?

Request a site visit with a technical survey, not a sales visit, and get at least three quotes. Ask for recommendations and addresses of installations in your local area that you could go and see. You can use Which? Trusted Trader to find trustworthy local solar panel installers recommended by other solar panel customers.

In order to take part in the Feed-in Tariff (FIT) scheme and earn money for generating renewable energy, your installer needs to be Microgeneration Certification Scheme-certified. You can check this on the MCS website

How can I ensure my solar installation goes well?

Make sure you don't end up with panels overhanging the roof. Where panels are fitted just above the existing roof, it's good practice to leave at least 30-40cm between the last panel and the roof edge to allow for access and to minimise the risk of strong wind blowing the panels off. 

So before your installer draws up the plans, ask how much space they're leaving between the panel and the roof's edge.

To ensure you get a thorough survey, use the Which? solar installation checklist