Solar Panels

This guide is about roof-installed, immovable solar panels for electricity generation, with ethical ratings for 19 solar panel brands. 

Read on to learn about carbon payback time, the cost of solar panels and what they’re made of, and how to get the most value from them.

We also highlight how companies scored for their climate action and materials used, discuss the issues with batteries, and the widespread risk of forced labour in a key material for solar panels.

Finding ethical solar panels

While still not the norm, the sight of solar panels isn’t a novelty any more. With the ongoing high cost of electricity, the increasingly evident impact of climate breakdown, and forthcoming regulations making them mandatory for new homes (under the Future Homes Standard legislation in England, and equivalent in Scotland and Wales), solar panel installations are on the rise.

Which is great news given their importance for decarbonising our home energy. 

Our Climate Gap report listed installing solar panels as the fifth most important thing consumers can do to make the highest carbon savings – behind ditching long haul flights and animal products, installing a heat pump and switching to an electric car.

Note, this guide is not about solar water heating (solar thermal), although we have a small section on this at the end of the guide.

How eco-friendly are solar panels?

The operation of solar panels – or photovoltaic (PV) systems – doesn’t create emissions while generating energy and that is one reason they are so much better than fossil fuels. 

However, the environmental impact of their manufacture is significant.

Solar panels are made primarily of silicon, made from quartz, which is mined from the earth and requires high heat for processing.

This accounts for the majority of carbon emissions from solar panels. China has been the world’s unrivalled leader in silicon production. But even though China’s power generation mix includes a growing proportion of solar power (12% in May 2024), coal still accounts for over 50%.

This means that almost inevitably, there will be a high amount of embodied carbon in solar panels.

Carbon payback of solar panels

However, according to the Renewable Energy Hub UK, due to the carbon saved by generating electricity with solar panels instead of fossil fuels, the embodied carbon should be paid back in 1-4 years. Even in the northern part of the UK where the sun is less strong, payback can be complete in the first six years of operation. 

Solar panels can last a long time (30-35 years or more), so will continue to deliver carbon savings for the rest of their lives.

As China and the rest of the world move more towards renewables, the embodied carbon in the panels will fall. Hopefully in the not-too-distant future, when panels are made using recycled materials, the carbon payback time will drop even further.

This doesn’t mean that solar panel manufacturers can rest on their laurels; they can and should cut their emissions. 

How much do solar panels cost?

It’s difficult to compare the price of solar panels because different suppliers sell different makes and charge different prices for their services, such as installation, maintenance, and warranty.

But as a ballpark figure, a 3.5 kWh system which generally fits on the roof of an average house (about 25 square metres), might cost around £7000. 

In England, Scotland, and Wales, homes will benefit from zero VAT on all energy-efficient measures until March 2027. In Northern Ireland, only people over 60 or receiving certain benefits are eligible for the zero rate. After March 2027, 5% VAT will apply.

Solar panel prices have increased over the past few years due to inflation, labour costs, and increased demand.

Luckily, there is financial help available in the form of grants. Check if you are eligible depending on where you live:

• England
• Scotland
• Wales

Local councils may also be participants in LA Flex (Local Authority Flexibility Scheme) or the Warm Homes grant (in England), Warmer Homes Scotland, Nest if you're in Wales, and other schemes in Northern Ireland.

Finance plans are also available but the interest rates vary. Some mortgage providers do have cashback deals for installing energy efficiency measures though, so if you are a mortgage customer of Barclays, Halifax, Lloyds, Santander, or Virgin Money this could help. Nationwide also offers a 0% interest loan.

Is it worth buying second hand solar panels?

With the ethical issues around solar panels, you may want to consider buying second hand. 

It can actually be a viable idea: solar panels can still work at around 96% of their capacity after 20 years of use. You need to be careful though, because solar panels are usually removed for a reason. So, ask questions before buying.

How to get the most value out of your solar panels

Once you have decided to invest in solar panels you are most likely in for a win. The Centre for Alternative Technology estimates you will recoup your costs in 10-15 years. As the panels should last for at least 30 years, they will provide free energy for the rest of their lifetime.

Most energy providers are required to purchase the surplus energy your panels are generating through the Smart Export Guarantee (SEG) scheme. To be eligible, residential solar systems are normally required to be accredited by the Microgeneration Certification Scheme (MCS).

The SEG rates don’t include transmission and distribution costs and therefore are lower than what you pay for when buying electricity from the grid. The rates vary even within providers depending on various conditions.

When we were researching this guide (summer 2025) 100Green and Octopus Energy offer the highest rate at 40p and 27p/kWh respectively. These are very high figures with strict conditions; the general rate is 15p/kWh although some providers only give as little as 5p/kWh. (See our guide to energy suppliers for how various companies rate.)

Compare that to the current 25p/kWh to use electricity from the grid and you can see that it pays to use the power you need while the sun is shining. Although using the generated electricity during the day may be easier said than done, there are ways.

If you own an inversion heater and a hot water cylinder, then by installing a power diverter you can shift the surplus energy there. Storage heaters can also use daytime energy to heat up, releasing it during specified hours. If not, you could make clever changes to your daily routine. Do the laundry, the dishes, and the cooking (if you have an electric hob) during daylight when you're generating solar energy, but do these one at a time so as not to overstretch the capacity of your system.

If you’re not home during the day, you could set timers and perhaps invest in a slow cooker that does the job while you’re away.

How do solar panel manufacturers rate for climate actions?

While many companies received marks because they make solar panels and are therefore focused on products that support the transition to a low-carbon economy, most weren’t doing enough to reduce the climate impacts of their production and operations. 

Only four companies scored over 70 points (out of 100) in our climate rating category:

• Canadian Solar
• JA Solar
• Jinko Solar
• LONGi (scored full marks) 

Solar panel materials

Depending on their type, solar panels are made of various materials. In this guide, most manufacturers produce monocrystalline and/or polycrystalline panels. The third main type, thin film solar panels, is usually used in building integrated photovoltaics, portable devices, transportation, and large-scale solar farms.

Because the manufacture of solar panels involves hazardous materials, raw materials mining, and high water usage, we developed a bespoke reference to rate all the companies on.

Although thin film panels are the most polluting ones, there are hazardous materials included in the manufacture of mono and polycrystalline panels, like potent acids and toxic gases.

Unless these are properly handled during manufacture and are recycled at end-of-life they will contaminate both soil and water.

Nevertheless, only eight companies appeared to have a priority list of hazardous chemicals: 

• Canadian Solar
• GB-Sol
• Hyundai
• LONGi
• Panasonic
• REC Solar
• Sharp
• Viessmann.

Silicon production requires a lot of water. Half of the companies took at least some action to reduce water usage: 

• GB-Sol
• Hanwha
• JA Solar
• JinkoSolar
• LONGi
• REC Solar
• Sharp
• TCL (Sunpower)
• Trina
• Vikram

GB-Sol said that it completely eliminated the use of water as part of the manufacturing process by making panels mainly by hand in smaller batches, rather than in a large, automated plant with bulk washing processes.

Overall, it was Sharp that scored highest for taking action to reduce the environmental impact of hazardous materials and silicon, followed by three other companies which scored 60 points, GB-Sol, LONGi, and REC Solar.

Tax conduct of solar panel companies

Only four companies scored full marks for our tax conduct rating: 

• Aira
• GB-Sol
• UKSol
• Yingli. 

Vikram scored 60 as it had one subsidiary in the tax haven of Singapore whose activity was unclear and therefore represented some risk of tax avoidance.

Two brands scored only 20 points (Hanwha and Sharp), and all the rest scored nothing, in our tax rating.
 

Israel boycotts

South Korean company Hyundai is currently the subject of a BDS boycott call because of the extensive use of Hyundai bulldozers by Israeli authorities in the demolition of Palestinian homes. 

A 2025 Amnesty report stated "images and videos ... identified 59 Palestinian-owned homes, businesses and other structures that were demolished between September 2019 and February 2025 using machinery made by the South Korea conglomerate. These demolitions resulted in the forced displacement of approximately 250 Palestinians and damaged the livelihoods of hundreds of others."

Workers' rights 

GB-Sol was the only company to score full marks in the workers rating, because it was a small company that manufactured in-house, and also had a relatively comprehensive supply chain policy. 

The only other companies in the guide which appeared to manufacture some products in-house were Aira (but not its solar panels), and Panasonic.

The next highest scorer after GB-Sol was UKSol which scored 40 (out of 100) for being a small company with long-term relationships with suppliers and basic labour standards. 

Many companies lost marks for criticisms relating to their exposure to forced labour in the Uyghur Region of China. 

Voice from the supply chain

It’s not possible to hear from Uyghurs forced to work in solar supply chains. Instead, we hear from a woman whose family was taken to ‘re-education’ camps, where many are made to work.

Rahima Mahmut is a Uyghur activist who has spearheaded campaigning in the UK to bring the Uyghur cause into the public and political arena. She directs the Stop Uyghur Genocide organisation.

“I left my country in 2000. 23 years in exile, I couldn’t return. None of my siblings could obtain a pass to come to visit me. Since October 2016, none of my siblings answered my phone calls. I had nine siblings I left behind.

“Finally, in January 2017, after repeatedly calling my eldest brother, who is like a father to me, he answered the call. Normally in my family, because my father is a very religious man, we greet people with ‘as salaam alaikum’. And my brother answered the phone ‘wei’. That’s the Chinese way of answering the phone, meaning ‘hi’. At the time I’d heard people say ‘as salaam alaikum’ was banned. I didn’t believe it, I thought it can’t be. I was taken aback when my brother said that.

“I said to him ‘why is no one answering my phone calls?’ and he said ‘They did the right thing’. Quietly, in a really shaky voice, he said ‘Leave us in God’s hands’ and put the phone down. “That’s the last time I spoke to anyone from my family. I was completely cut off. I know if I actively reach out to anyone, I’ll put them at risk.”  

The above text was paraphrased from a YouTube interview with Middle East Eye. You can watch the whole video on YouTube.

Materials used in batteries to store energy

It’s important to talk about batteries as they are becoming increasingly popular for storing solar-generated energy but their production is associated with severe environmental harm and human rights abuses. 

Also, batteries are expensive and not needed when you can sell the energy back to the grid. 

Given supply issues, some argue that battery production should be prioritised for electric vehicles which do need them.

Below we look at some of the main problematic materials used in batteries for storing solar energy.

Lithium

Lithium-ion batteries are currently the most popular type in the UK for solar energy storage. 

Lithium extraction can be extremely environmentally damaging. It pollutes water sources, diverts water away from farming, produces massive waste, uses a huge amount of electricity, and increases CO2 emissions through destruction of vegetation in mining areas. As demand increases, innovations will hopefully be made to reduce the damage done. 

The world’s largest lithium mining nations are Australia, China, Chile, and Argentina. Some analysts predict that, if battery power replaced oil, South America would become the “new Middle East”.

Cobalt

Another issue with lithium-ion batteries is the mining of the rare earth minerals they contain, such as graphite, nickel, and cobalt. The ores of these minerals are typically mined in Central Africa, where regulations protecting workers’ rights are weak. Southern Democratic Republic of Congo sits atop an estimated 3.4m tonnes of cobalt, almost half the world’s known supply.

While conflict minerals such as those used in mobile phones are included in US and European (although not UK) regulations, cobalt isn’t.

Investigation has revealed severe environmental and social impact in artisanal mines, where up to a fifth of the cobalt production takes place. Workers have complained of issues such as long working hours, lack of protective gear, and child labour.

Recycling batteries

It is expected that at least 11m tons of used lithium-ion batteries will accumulate worldwide by 2030. 

Recycling solar batteries is critical because they contain highly toxic materials, but the number that are getting recycled is unclear. Thankfully, the lithium battery recycling market is expanding.

Alternative battery storage

Several alternatives are being researched by scientists trying to find cheaper, more environmentally friendly energy storage. These include batteries made of salt, glass, or even sea water and hemp! 

Prototypes of sodium-ion batteries are starting to appear.

What about solar water heating? 

According to the Energy Savings Trust, hot water accounts for around 11% of the average energy bill. 

Solar water heating is also known as solar thermal.

It does not require bright sunlight in order to function, and can still heat water on cloudy days. Even in the UK.

It works by the sun heating a liquid in either tubes or panels on your roof. This liquid is sent through pipes to your hot water cylinder. As the hot liquid flows through these pipes, it warms up the water in your cylinder.

As it only heats water, you will need another source of energy for space heating. And although it can produce most or even all your hot water in the summer months, for winter in particular, you will need alternative ways of making hot water.

Because it uses a cylinder it is difficult to add solar thermal to a heating system that doesn’t include a hot water cylinder e.g. a ‘combi’ boiler that heats water on demand when you turn on a hot water tap or have a shower.

It also doesn’t heat water to a high enough temperature to be used in traditional radiators, although it can be combined with a conventional boiler or immersion heater to make the water hot enough for this.

If you do install a solar water heating system, it's best to insulate your pipes and water tank to make your system more efficient. You can also adapt to using the hot water later in the day as it’s had more time to heat up.

The market for solar thermal has declined since solar photovoltaic panels became cheaper and more popular and many solar thermal companies stopped trading.

Not all energy efficiency grants are open to solar water heating, so check first.

Find out more about solar water heating:

• Centre for Alternative Technology
• Energy saving Trust
• Which?

Additional research for the guide by Katalin Csatadi.