The Independent’s journalism is supported by our readers. When you purchase through links on our site, we may earn commission. Why trust us?

Solar panel definitions: Bust the eco jargon

Verified by Amy Reeves

Whether you’re new to the world of solar or not, there’s a lot of jargon that comes with this topic. This can make it tricky to make informed decisions when it comes to installation or opting into any solar incentives, which is why it’s important to understand what solar terminology means. We’ve compiled a list of some of the most useful solar terms and explained them in a simple and digestible way.  

Benefits of solar energy: 

  • Reduce your energy bills by up to £610 annually
  • Reduce carbon footprint
  • Have a constant supply of renewable energy
  • Potential to earn money by selling solar energy back to the National Grid

What is a solar panel?

Solar photovoltaic (PV) panels convert sunlight into usable electricity by using cells, usually made from silicon, a semiconductor material, embedded in a metal frame with a glass casing. 

Solar thermal panels are another type of solar panel that can utilise the sun’s power. They work by using the sun to heat a fluid in tubes on the roof that, in turn, can supply domestic hot water instead of power. This type of panel is cheaper than PV panels and tends to be more efficient, especially as heat waves carry more energy than sunlight. 

Some solar panels combine thermal and photovoltaic technologies, these are known as hybrid solar panels, or solar PVT (photovoltaic thermal) panels. This type of panel can produce both heat and electricity through the combined module. A hybrid solar system allows for continuous power, the system channels electricity through a hybrid inverter and battery with the surplus electricity being passed along to the grid and the rest is stored in the home’s battery for usage. 

What does photovoltaic mean?

The photovoltaic (photo meaning light and voltaic meaning electricity) effect is a process that creates voltage or electronic current in a cell when it’s exposed to sunlight. 

What is a solar cell?

Solar cells are made up of different types of semiconducting materials that are joined together – this creates an electric field that can be used to create electricity. 

There are three types of solar cells:

Monocrystalline cells are made from single-crystal silicon solar cells. Pure silicon is formed into bars before being cut into pieces. The edges are smoothed and rounded to help cells produce more electricity. They are the most expensive panel type but are also the most efficient type of solar panel. Typically they have an efficiency rating of 20 per cent or more. 

Polycrystalline cells are also made from silicon by melting many fragments of silicon crystal together. This type of solar cell is less efficient than monocrystalline and typically has an efficiency rate of between 14 and 17 per cent.

Thin-film solar cells are thin and manufactured by layering multiple products such as silicon, cadmium telluride and copper indium gallium selenide. They’re the least efficient of all three types and only have an efficiency rating between 7 and 18 per cent. 

What is an alternating current (AC)?

An alternating current (AC) is an electric current that changes its magnitude at regular intervals. AC is the preferred power for solar panels, typically solar panels generate DC, and this is then converted into AC because it is safer to channel AC power into homes or buildings. 

What is a direct current (DC)?

Direct current (DC) is one-directional, meaning the electric charge only flows in one direction. Solar panels produce DC when sunlight reaches the panels this sunlight is converted into direct current. For solar panels that are connected to the National Grid, it’s best if DC is converted to AC, due to its higher power output.  

What does a solar array mean?

A solar array is a group of connected solar panels to generate electricity from the sun. An array is then wired to a solar inverter.

What does a solar panel inverter do?

Simply put, a solar panel inverter converts DC energy into AC. Solar panels generate DC but AC is the standard flow of electricity used in UK home appliances and the current that is compatible to be connected to the National Grid. Therefore, in order to safely use solar panels’ energy, a solar inverter is required.

What are solar storage batteries?

These allow you to store electricity generated by solar PV panels to use at times of the day when your system isn’t generating any electricity, such as at nighttime. Solar batteries can also be useful in times of low-light conditions in winter, which can affect solar generation – you’ll be able to use your stored energy at any time of day.

Why does an energy audit matter?

This is a process that assesses a home’s energy consumption. It is the first step that a homeowner should take before installing solar panels. The audit can help reveal areas where your home is not energy-efficient and your auditor can calculate the energy requirements for your home and the size of your solar array.

What is a watt, kilowatt and kilowatt-hour?

Watt (W) describes the rate at which electricity is being used at a specific time and kilowatt (kW) is 1000W and is used as a measurement for the rate of power an electrical appliance uses. 

A kilowatt-hour (kWh) is the standard unit for measuring electrical power – you will come across this term a lot in reference to solar panels. kWh specifically refers to the measure of power it takes to run a device per hour. For example, 1kWh is the amount of energy it takes to run a 1kW device. 

What is solar panel efficiency and why is it important?

This refers to the amount of energy generated that can be converted into usable electricity. Solar PV panels are measured based on the percentage of energy that is converted. The higher the panel’s ability to collect energy from photons (light particles) and convert it into usable electricity, the higher its efficiency percentage will be. The best solar panels have an efficiency percentage of around 20 per cent– this means they’re able to convert 20 per cent of sunlight into usable energy.    

How does power output work?

A solar panel’s power output is measured in watts (W) and it refers to the panel’s power production in ideal weather conditions. So, if a solar panel’s power output is 400W, this is how much solar power the panel can generate in a given amount of time.

What is solar panel degradation?

Degradation refers to the time it takes for solar panels to decrease in efficiency. Solar panels naturally reduce in efficiency over time and a manufacturer will calculate this over the panel’s lifespan. Typically, a solar panel will degrade between one and two per cent in the first year and after that tend to degrade around one per cent per year. 

What is a solar panel product warranty?

A solar panel’s product warranty covers any defects that may occur post-installation. Product warranties can range from five years to 25 years, with the best suppliers offering lifetime guarantees. A solar panel has an average lifespan of 25 years, so ideally your product warranty covers the entirety of its lifespan.  

Why is a performance warranty for solar panels important?

The performance warranty focuses on the power output of the product. A manufacturer’s performance warranty will usually cover a longer period than the product warranty and will be measured in the form of product efficiency. The warranty will state that the product should perform at a certain percentage of the panel’s maximum power output it had on the day it was installed.

What is a Distribution Network Operator (DNO)?

A Distribution Network Operator (DNO), is a company licensed to distribute electricity throughout the UK. A DNO owns and operates network cables, connecting generators and towers that transmit electricity for homes and businesses. When you’re installing solar panels and need to connect them to the National Grid, you’ll need to contact your DNO in order for the electricity to be monitored and calculated properly.  

What is the Smart Export Guarantee (SEG)?

The Smart Export Guarantee (SEG) enables small-scale generators to be paid for the energy that they generate. Although not a solar panel grant, the scheme obliges large energy suppliers to offer an export tariff that pays its customers for the surplus energy that they export back to the national grid, easing the initial cost of solar panels

What is the Microgeneration Certification Scheme?

The Microgeneration Certification Scheme is an organisation that creates and maintains standards for small-scale renewable electricity technologies. It provides consumer protection for installers and installations. It is also a requirement that your solar system is installed by an MCS-accredited installer for the SEG scheme where homeowners can be paid for selling solar energy back to the National Grid.

What is the National Grid network and what are grid-connected systems?

The National Grid network’s primary function is to ensure that all parts of the UK have access to enough power. It comprises high-voltage power lines, gas pipelines, interconnectors and storage facilities that work together to distribute electricity within the UK. 

A grid-connected solar array is connected to the National Grid via a power inverter. Grid-connected systems allow homeowners to power their homes with renewable energy during sunlight hours but also utilise grid electricity during the night time – any surplus energy generated during daylight hours can be fed back into the grid. 

Why is roof pitch important?

Solar panels collect the most amount of sunlight when they are mounted at between 30 and 35 degrees. Since most domestic solar panels are roof-mounted, a home’s roof pitch needs to be between these angles in order to capture the maximum amount of sunlight hours and generate a good amount of renewable energy. However, solar panels can still be installed if your roof pitch is outside of these parameters, or is a flat roof.

What are solar panel mounting systems?

Solar panel mounting systems are what is used to fix solar panels on different surfaces such as roofs, on the ground or other parts of a building. These mounting systems are used not only to fix the solar panels to the desired place but also to ensure the solar panels are kept at the correct angles in order to maximise sunlight exposure. 

Another way to secure solar panels is to install a ballast block. These are non-evasive blocks used to secure temporary and permanent structures, including solar panels. Made from dry-cast concrete they’re durable and long-lasting and are commonly used in solar farms or for flat roofs. 

For ground-mounted systems, some solar panels are secured on a pole. The pole may use a single or dual-axis system; this allows the solar array to follow the direction of the sun and maximise sunlight exposure. 

Solar incentives and rebates

Solar panels are an excellent way to reduce your carbon footprint and save money on your energy bills. There are also a few solar incentives set up by the UK government to encourage homeowners to make the leap towards a more sustainable way of living. The UK’s green policy hopes to cut emissions by 68 per cent by 2030, which is why it has reduced solar panels VAT to 0 per cent and, through its Energy Company Obligation (ECO4) scheme, homeowners who are already claiming benefits may be eligible for free, or subsidised, solar panels. 

The SEG enables small-scale generators to be paid for the energy that they generate, and this includes solar panels. Though there are a few specifics to qualify, such as your solar array must be installed by an MCS-accredited installer, the scheme is widely available for all UK homeowners to reap the benefits from.

Solar incentive Run time Potential savings
ECO4 April 2022 to March 2026 Partially or fully free solar panels
SEG From 1 January 2020 (indefinite) 1p – 24p per kWh of excess electricity produced by solar panels
0% VAT April 2022 to March 2027 Savings dependent on solar panels cost

Maintenance and troubleshooting solar panels

Fortunately, solar panels are low maintenance and require very little looking after throughout their average 25-year lifespan. 

To ensure your solar system functions at maximum efficiency, you should: 

  • Service your solar panels once every five to 10 years
  • Check your solar panel’s power output regularly, if you notice any sudden drop in output; most likely your panels need to be checked by a professional
  • Clean your solar panels once per year. You should only do this from ground level using a hose with low water pressure – never attempt to climb on top of your roof

Environmental benefits of solar panels

Solar panels generate sustainable renewable energy and this has a positive effect on the environment. Its main benefit is its reduction in carbon emissions, which is the main contributor to climate change. 

  • Reduce your carbon footprint by up to one tonne per year
  • Reduces water pollution, as the total amount of water needed to generate solar energy is significantly less than is required for natural gas, coal, nuclear and hydroelectric facilities
  • Reduces strain on finite resources, such as oil, coal and natural gas 

Frequently asked questions about solar panel jargon busting

The average cost of solar panel installation in the UK is £5,500 for a 4kW system that would suit a three-bedroom household. However, the exact cost of your solar panel system will largely depend on your home’s energy consumption and system size.

Solar panels are a long-term investment; the average solar system will have a lifespan of around 25 years. This means that you should see a return on your investment before the panels need to be replaced and begin to earn money back through SEG payments and reduced energy bills.

You should never install solar panels yourself. It’s too dangerous to DIY install solar panels, as it involves needing access to a roof and dealing with electrical equipment that only trained installers are qualified to deal with. Also, if your solar panels are not installed by MCS-accredited installers, this means you won’t be eligible to receive SEG payments from selling surplus solar back to the grid.

Fortunately, solar panels require very minimal maintenance. However, you should clean them annually using a hose from ground level and have them serviced once every five years. If you don’t wish to clean them yourself, you could hire a professional to clean them for as little as £4 per panel.

Solar panels still work in cloudy weather. Although they are most efficient on sunny days, solar panels can still reach between 10 per cent and 25 per cent of their maximum power output when the weather is cloudy.

rachel

Rachel Sadler

Home Tech Writer

Rachel is a seasoned writer who has been producing online and print content for seven years. 

As a home tech expert for Independent Advisor, Rachel researches and writes buying guides and reviews, helping consumers navigate the realms of broadband and home security gadgets. She also covers home tech for The Federation of Master Builders, where she reviews and tests home security devices. 

She started as a news and lifestyle journalist in Hong Kong reporting on island-wide news stories, food and drink and the city’s events. She’s written for editorial platforms Sassy Hong Kong, Localiiz and Bay Media. While in Hong Kong she attended PR events, interviewed local talent and project-managed photoshoots. 

Rachel holds a BA in English Language and Creative Writing and is committed to simplifying tech jargon and producing unbiased reviews.

Amy Reeves

Editor

Amy is a seasoned writer and editor with a special interest in home design, sustainable technology and green building methods.

She has interviewed hundreds of self-builders, extenders and renovators about their journeys towards individual, well-considered homes, as well as architects and industry experts during her five years working as Assistant Editor at Homebuilding & Renovating, part of Future plc.

Amy’s work covers topics ranging from home, interior and garden design to DIY step-by-steps, planning permission and build costs, and has been published in Period Living, Real Homes, and 25 Beautiful Homes, Homes and Gardens.

Now an Editor at the Independent Advisor, Amy manages homes-related content for the site, including solar panels, combi boilers, and windows.

Her passion for saving tired and inefficient homes also extends to her own life; Amy completed a renovation of a mid-century house in 2022 and is about to embark on an energy-efficient overhaul of a 1800s cottage in Somerset.