Interest in solar power generation is on the rise, and this guide aims to address some of the most frequently asked solar questions.
Research commissioned by the UK government’s Department for Energy Security and Net Zero (DESNZ) shows that information and understanding are likely opportunity barriers to adopting solar power.
44% of participants considering installing solar panels stated that information about solar panels is very complicated, with 40% saying they find it confusing.
Installing solar panels is a big investment for many households and SMEs, so getting answers to the most frequently asked solar questions can help alleviate concerns and ensure you make an informed decision about your energy future.
1. How Do Solar Panels Work?
Solar panels work by converting sunlight into usable electricity through the photovoltaic (PV) effect. Each panel has multiple solar cells, typically made from silicon, a semiconductor material.
When the cells absorb sunlight, electrons get excited and move, creating an electric current. This current is in the form of direct current (DC), which is not suitable for home use. An inverter converts the DC into alternating current (AC), making it ideal for home and business use.
Once converted to AC power, the electricity flows through your property’s electrical system, powering appliances and lighting. If the panels produce excess electricity, you can store it in a battery for later use, especially at night or during low sunlight periods.
You can also feed the excess back into the grid through the Smart Export Guarantee (SEG) and earn money for surplus energy.
2. How Much Do Solar Panels Cost?
The cost of solar panels in the UK varies depending on panel efficiency, system size, location, installation complexity, and additional features like battery storage.
On average, a single 350-watt panel costs between £150 and £300. However, this is only one panel and does not include installation costs and extras. The most common solar panel system in the UK is a 3.5 kilowatt-peak (kWp), which would require around 10 solar panels.
The Energy Saving Trust notes that the 3.5 kWp solar panel system can cost around £7,000. However, costs can go as high as £10,000 for high-quality solar panels and larger systems with higher energy outputs.
3. How Long Do Solar Panels Last?
Solar panels are built to last. Most manufacturers offer 25 to 30-year warranties. However, this does not mean that the panels stop working after that period. Instead, their efficiency gradually declines over time.
A well-maintained system can continue generating electricity for 35 years or more, although at a slightly reduced output.
Most solar panels lose about 0.5% to 0.8% efficiency per year, meaning that after 25 years, they typically operate at 80% to 90% of their original capacity. Higher-quality panels degrade more slowly, allowing them to maintain performance for decades.
Factors that can affect your solar panels’ lifespan include:
- Panel Quality — Premium monocrystalline panels tend to last longer and degrade more slowly than polycrystalline panels.
- Weather Conditions — Panels can withstand rain, wind, and snow, but extreme weather (hail and storms) can impact longevity.
- Maintenance — Regular cleaning and inspections help prevent debris buildup and damage, preserving efficiency.
- Inverter Lifespan — While panels last for decades, you may need to replace the inverter after about 12 years.
- Installation Quality — Proper mounting and wiring reduce strain and improve system longevity.
You can maximise your solar panels’ lifespan by keeping them clean to avoid dirt, trimming overhanging trees to prevent shading and debris accumulation, and scheduling a professional inspection at least once every two years to check for any wear or damage.
4. Why Are Solar Panels Not Worth It?
While solar panels offer benefits like lower energy bills and reduced carbon emissions, they are not a perfect solution for everyone. Several factors can make solar panels less cost-effective or impractical for some homeowners.
High Upfront Costs
The initial investment, including installation, inverter, and optional battery storage, can range between £5,000 and £10,000.
While prices have dropped over the years, not everyone can afford the upfront expense, and the payback period can take 10-20 years, depending on energy usage and government incentives.
Limited Savings for Low-Energy Users
Homes with low electricity consumption may not benefit from solar panels. If your annual electricity bill is already low, the savings from solar panels might not justify the installation cost, extending the payback period significantly.
Poor Roof Suitability
Some roofs are unsuitable for solar panels. A north-facing roof, heavy shading from trees or buildings, or an unsuitable roof structure can reduce efficiency, making the system less cost-effective. If you have limited roof space, you may also struggle to install enough panels to make a difference in energy savings.
Weather Dependency
Clouds and other obstructions like trees can impact the amount of energy your panels generate.
If you live in an area with less sunlight and more cloudy and rainy weather, you may experience reduced energy output, leading to lower savings. Shorter daylight hours in winter also mean less solar generation when energy demand is typically higher.
Recycling and Waste Challenges
While solar panels promote clean energy, their disposal is problematic. Panels contain materials like silicon, glass, and metals, which require specialised recycling processes.
Currently, solar panel recycling infrastructure is limited, leading to concerns about waste management as older systems reach the end of their lifespan.
5. How Do You Get Free Solar Panels from the Government?
The UK government does not typically provide completely free solar panels, but some schemes help reduce costs or allow specific households to access solar energy with little to no upfront payment.
These programs are designed to encourage renewable energy adoption and support low-income households in reducing energy bills. Government schemes and green finance options you can use include:
The ECO4 Scheme
The Energy Company Obligation (ECO4) mandates energy suppliers to offer efficiency improvements to eligible vulnerable and low-income households across England, Scotland, and Wales.
You can qualify to get solar panels installed under the scheme if your property is already heated via a heat pump or electric heating system with a 0.8 or higher SAP responsiveness rating.
Warm Homes: Local Grant
Through the Warm Homes: Local Grant scheme, the UK government has partnered with combined authorities and local and devolved governments to support solar panels and other energy-efficient measures.
It targets low-income households living in the worst-quality, privately owned homes in England and aims to cut family bills, slash fuel poverty, and reduce carbon emissions in support of the net zero 2050 targets.
6. How Many Solar Panels Do I Need?
Factors like your household’s energy consumption, the panels’ efficiency, and available roof space will influence the number of panels you need. Ofgem estimates that a typical UK household consumes around 2,700 kWh of electricity per year, meaning a 3-4 kWp (kilowatt-peak) solar system is usually sufficient.
Look at factors like:
- Energy Consumption – Homes with higher electricity usage require more extensive systems. A family using 4,500 kWh per year may need a 5-6 kWp system.
- Panel Efficiency – Higher efficiency panels generate more power per square metre, reducing the number required.
- Roof Size – The amount of space available will influence the number of panels that can fit on your roof. Limited roof space may require fewer high-efficiency panels, while larger roofs allow for more standard panels.
- Battery Storage – If a battery is used, a larger system may be beneficial to store excess electricity for later use.
Consulting a professional installer is the best way to determine how many solar panels you need. They can assess requirements and recommend the best system size for maximum savings.
7. How to Clean Solar Panels?
Solar panels don’t need much maintenance, but occasional cleaning helps maintain efficiency by removing dirt, bird droppings, dust, and debris that can block sunlight.
In the UK, rainfall usually keeps panels clean, but grime can build up over time, especially in dry periods or near trees.
You’ll need to clean your panels if they have visible dirt or a drop in energy production. Signs that panels need cleaning include lower energy output than usual, visible dust, dirt, or bird droppings blocking sunlight and nearby trees, or pollution that increases debris accumulation.
When cleaning your panels, ensure you:
- Turn Off the System – Switch off the solar panel system before cleaning to prevent electrical hazards.
- Use a Soft Brush or Cloth – Avoid abrasive materials that could scratch the glass. A soft sponge or microfiber cloth is best.
- Use Mild Soap and Water – Mix lukewarm water with a mild detergent or biodegradable soap. Avoid harsh chemicals, as they can damage the panel coating.
- Rinse with Clean Water – Use a hose with low pressure to wash away soap and dirt. Avoid high-pressure washers.
- Let the Panels Dry Naturally – Air drying prevents streaks or smudges.
You can hire professional cleaners for hard-to-reach panels or large solar systems. They ensure safety and effectiveness by using specialised equipment to clean panels without damage.
8. How Efficient Are Solar Panels?
Solar panel efficiency is the amount of sunlight a panel can convert into usable electricity. Most residential solar panels in the UK have an efficiency rate of 15-22%, meaning they convert 15-22% of the sunlight they receive into electrical power.
Solar panels perform best in cool, sunny environments. Excessive heat can slightly reduce efficiency.
Angle and orientation can also impact efficiency. In the UK, south-facing panels at a 30-40 degree tilt generate the most power. East- and west-facing panels still produce electricity but at lower rates. Dirty or obstructed panels absorb less sunlight. Occasional cleaning ensures maximum efficiency.
The panel type can also influence efficiency. Monocrystalline panels are the most efficient, with rates of 18-22%, but also the most expensive. Polycrystalline panels are slightly less efficient at 15-18% but more affordable. Thin-film panels typically have lower efficiency (10-12%) but are lightweight and flexible.
9. What Are Solar Panels Made Of?
Solar panels are made of multiple layers of materials designed to capture sunlight and convert it into electricity efficiently. The primary components include:
Solar Cells (Photovoltaic Cells)
Photovoltaic (PV) cells convert sunlight into electricity. They are made primarily from silicon, a semiconductor material that facilitates the movement of electrons when exposed to sunlight. Solar cells can be monocrystalline, polycrystalline, or thin-film.
Glass Layer
The solar cells are covered with highly durable tempered glass, which protects them from environmental damage such as rain, hail, and debris. The glass is also anti-reflective to ensure maximum sunlight absorption.
Encapsulant Layers
Encapsulants are transparent materials that hold the solar cells in place and protect them from moisture and temperature variations. They help extend the lifespan of the panel by preventing air or water infiltration.
Back sheet
The back sheet is a protective plastic or polymer layer that insulates and shields the panel from humidity and other external elements.
Metal Frame
The frame, typically made of aluminium, provides structural support, ensuring durability and making installation easier.
10. What Are the Benefits of Solar Panels?
Lower Energy Bills
Solar panels allow you to generate free electricity. This reduces your reliance on the grid and offers significant savings on electricity costs. According to the Energy Saving Trust, homes using solar panels with export payments and a solar diverter in London can save up to £690 annually, depending on energy consumption.
Renewable & Sustainable Energy Source
Solar power is an infinite, clean energy source that reduces reliance on fossil fuels, cutting carbon emissions and helping combat climate change. The Energy Saving Trust notes that you can save around one tonne of CO₂ per year, depending on where you live in the UK.
Increased Property Value
Panels increase property values since they offer lower energy costs and sustainability benefits. Findings from a study on the value of solar property show that installing a solar energy system can increase the sales price of a typical home by at least £1,800.
11. How Big Are Solar Panels?
A solar panel’s size will depend on its type and purpose. Residential solar panels typically measure around 1.7 metres by 1 metre (170cm x 100cm) and have a thickness of about 3-5cm. These panels usually generate between 300W and 400W of power each.
A standard home solar system of 3-4 kW would require approximately 8-12 panels, covering around 15-25 square metres of roof space.
Larger solar panels, often used for commercial or industrial installations, can be bigger, measuring up to 2 metres in length and generating over 500W per panel. These systems require more space but provide greater energy output.
Ground-mounted solar panels offer an alternative solution if roof installation isn’t suitable,
Sources and References
- https://solarenergyuk.org/wp-content/uploads/2021/10/The-Value-of-Solar-Property-report_SEUK.pdf
- https://assets.publishing.service.gov.uk/media/60edea3b8fa8f50c7f08ae1e/uk-rooftop-solar-panel-behavioural-research.pdf
- https://energysavingtrust.org.uk/advice/solar-panels/
- https://www.ofgem.gov.uk/sites/default/files/2024-04/eco4_delivery_guidance_v2.1.pdf
- https://assets.publishing.service.gov.uk/media/66f1573cbd3aced9da489bcf/Warm-Homes-Local-Grant-guidance.pdf
- https://www.ofgem.gov.uk/information-consumers/energy-advice-households/average-gas-and-electricity-use-explained