You’re being smart in choosing to prioritise energy efficiency. It benefits the environment and saves you money. There’s just one thing – how many solar panels do you need? Well, in this guide, we’ll help you find out.

Read on to find out more about sizing, the number of solar tiles you need and how to install solar panels on a tile roof.

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What size roof tiles do I need?

This a common question, but not something you may need to consider. Instead, you need to know how many panels you need for the solar array.

Wait, what is a solar array?

A solar array is what the group of panels is when put together. For example, you have four panels. You connect them together in a square formation. That is one array. It is what will help collect the rays and convert that into energy.

Now, the number of solar arrays will depend on energy requirements and solar tile output. This output is measured in kWp (kilowatt peak). You can find out more about the kWp measurement below.

Once you’re familiar with kWp, you can now move on to learn what you need to consider when buying solar tiles.

How many solar tiles do I need?

The Department for Business, Energy and Industrial Strategy has found that the Average UK home uses 3,600kWh of electricity per year.

With some calculations, Marley find that the typical home would need at least 16 solar panels. Now, this isn’t a one size fits all scenario. Other factors will come into play. These can be:

  • The size of the house.
  • How many people live there.
  • The location of the property.
  • The number of hours of sunshine expected each day.
  • Whether you will use solar to provide electricity to all or some places.

There are many more things to consider when buying solar panels or solar roof tiles for a roof. Here is a breakdown of what to consider when buying solar panels or solar tiles.

what to consider when buying solar roof panels

Is your roof sloped or flat?

The average slope for a home roof in the UK is 30 degrees. Zero degrees is a flat roof. If your roof is 90 degrees, think carefully about your PV panels. You’ll want to consider installing these on a vertical surface (I.e., a wall).

pitched roof tilesflat roof

How much of your roof is shaded?

Are you surrounded by trees or buildings? Perhaps your property is on open land.

There is no use installing panels that won’t see the sun. Generally, if there’s barely any shading (less than 20% of the sky), you can most likely fit the panels where you like (other factors permitting). However, if there’s a lot of shading (more than 80% of the sky), consider where your panels need fitting to get the most exposure.

clay roof tiles

What direction is your roof facing ?

No, this isn’t feng shui. It really does matter what way your roof is facing.

According to professionals, south-facing roofs are the best for solar power collection. Having said that, if you have a flat roof, you won’t have the panels facing any direction.

You don’t have to get the exact direction, but you should get as close as possible. Doing so guarantees you a better idea of the size of panelling you will need to achieve your energy goals.

What size solar tiles do you need to install?

So, this is the big question. What will you need to calculate?

Each size will affect the level of kWp (kilowatt peak). Common sizes include whole numbers between 2kWp and 10kWp, with 2.5kWp and 3.5kWp as exceptions.

For domestic properties, the average size is medium, which equates to 4 kWp. You should also expose your solar system to as much sunlight as possible, ideally a range of 10m2 to 20m2 of unshaded space.

You can opt for a system on the smaller side, but this isn’t cost-efficient.

You’ll most likely see the average solar panel at two square metres in size – two metres in length by one metre in width.

That said, individual Marley Solar panels measure 1000mm x 1686mm. Better yet, you can use the solar panel configuration tool to calculate how many solar roof tiles you need to meet your kWp (Kilowatt peak) requirements.

At what times of the day will you be at the property?

Do you work during all hours of the day? Maybe you work part-time or spend a lot of days at home.

How often you’re using the property will affect how much electricity you use. So, finding an estimate can contribute to finding out the right size system for your requirements.

Example scenario for buying solar roof tiles

Here is an example of a solar energy user and their requirements. They want to save at least £230 a year and spend under £10,000 for a new system. So, they check out their roofing and properties position to note the following:

  • Roof slope is 30 degrees
  • Modest shading (about 30%)
  • Southeast facing roof
  • Medium 4kWp installation sized
  • Working from 8am until 4pm

With some calculations, they find they can have a potential saving of around £230 per year and an estimated fitting cost of £6000.

Although ideal, they want to try and shrink the installation cost. So, they adjust the size to 2kWp. After calculating, this new figure says there is a potential saving of around £170 per year and an installation cost of around £4000.

This new system is cheaper to install in the short term but leaves little room for annual benefit. So, what can you do in this situation?

The best thing you can do is get at least three quotes. Compare each quote, ensuring you consider planning permission, and work out what’s best for your requirements.

Please remember these are estimates and not an accurate representation of what you may get. However, it will help you understand what you will need to consider. As always, speak to your solar panel provider for more advice.

How to install solar tiles on a tile roof

Typically, solar panels and mounting systems should be installed one at a time. Starting from the bottom left corner of the roof.

Some solar tile kits, like Marley’s, are colour coded. This makes following the manufacturer’s instructions easier to work with.

You can find out more about installing Marley solar tiles in our guide. Find out why you should choose Marley solar tiles, including an in-depth video about how to install them.

Installing Marley solar roof tiles

Where to buy solar roof tiles

You can find and purchase solar roof panelling right here at our Superstore! We have many solar tiles for you to choose from. Whether you need a single replacement panel or multiple panels, we can cater to your requirements.

Want to know more about solar roof tiles themselves? Read through our solar roof tile buyer’s guide for information about the types of solar tiles, efficiency facts and more.

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