Solar Panels

Demand for solar panels is soaring. With more people wanting to live in a greener way and a full-blown global energy crisis underway, renewable energy is more attractive than ever.

This guide is about roof-installed, immovable panels for electricity generation. We review 16 companies making solar panels - or photovoltaic (PV) systems - and with one company scoring zero points and several others languishing near the bottom of our score table, there are differences between the brands in this market.

Read on to learn about supply chain ethics, the cost of solar panels and how to get the most value from them.

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. As a rule of thumb though, Chinese-owned companies’ panels tend to be cheaper than those that only manufacture in China.

Although over the past decade the price of solar panels has come down significantly, they are still not affordable for the general population. We looked at a few quotes and a 3.2 kWh system (depending on the manufacturer this is eight to twelve panels) will set you back £4-7000.

Homes will benefit from zero VAT on all energy efficient measures until 2027. But be aware you only get one VAT-free purchase so if you thought that you'd buy solar panels and then save up and add a heat pump in a couple of years, think again. Either you buy them together or cough up the VAT on further purchases.

Even without VAT, not many people have several spare thousands in the bank, let alone several thousand more for a battery (see later).

Loans are available but, depending on the interest rates, this would add 25-50% on top of the base cost (and who knows how your bank will use the money it makes – see our guide to ethical mortgages).

There is help available, though, in the form of grants and interest free loans (both subject to eligibility and availability). Check out www.eco4.org.uk in England, www.gov.scot in Scotland and www.nest.gov.wales in Wales for more information.

Are solar panels worth the investment?

Once you have decided to invest in solar panels you are most likely in for a win. Based on the Energy Saving Trust's figures, it could typically take 8-12 years to recoup the costs of installing panels. From April 2023, when the price of electricity is predicted to increase yet again, this may become a shorter timescale.

It might sound obvious, but the more you use them, the quicker the investment will pay for itself.

If you don’t have a solar battery, you'll want to put the generated energy to good use. Most 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. At the moment one of our recommended energy suppliers, Octopus Energy, offers the highest rate at 15p per kWh while EDF only gives 1.5p. Compare that to the current 34p per kWh you pay to use electricity from the grid and you will want to use every single kWh your solar panel generates, otherwise you will still have to purchase energy from the grid when the sun is not shining.

Incidentally, this is when UK households use the most electricity: in the morning and in the evening. (This is one reason why photovoltaic energy is a better fit in hotter countries, where electricity use often peaks in the middle of the day when people are using air conditioning).

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 but do 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 out.

If your concern is the climate, you should aim to deal with your heating first: insulate your home and consider getting a heat pump. The heat pump can be run through electricity generated on your roof.

Heating needs to be addressed at the domestic level, but electricity for this cool and breezy island could be better addressed with offshore wind farms than domestic solar panels.

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, solar panels are usually removed for a reason. So ask questions before buying.

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 and disposal is significant.

The carbon footprint of solar panels

Solar panels are made primarily of silicon, which is mined in open pit mines and requires high heat for proper shaping. They also contain metals and rare earth minerals, which are mined and transported.

This is all mostly done with fossil fuels and thus has a carbon footprint: a typical house array of ten panels, each with a peak capacity of 350 watts, will have an embodied carbon footprint of around two tonnes.

Our total annual carbon footprint in the UK is about 12 tonnes each, so this looks like a sizeable proportion. But solar panels last a long time - the latest solar panel models on the market have an expected lifespan of 40-50 years. Even on our gloomy and dark island their carbon footprint can be paid back in the first six years of their operation. If you live somewhere sunnier, this can go down to as little as 1.5 years.

Furthermore, the embodied carbon in the panels has been falling dramatically and it is predicted that in the not too distant future, when they are made using recycled materials, the carbon payback time will be less than half this. For the rest of the solar panels’ lifetime their overall carbon footprint drops into the negative and owners can enjoy truly carbon-free electricity, knowing that their system will save over 900 kg of CO2 per year.

This doesn’t mean that solar panel manufacturers can rest on their laurels; they can and should cut their emissions and, as solar panel manufacturers, they have the means to do so. Our carbon rating showed that most of them weren’t doing enough, with only Canadian Solar, LONGi, and Panasonic getting best ratings.

Pollution linked to solar panels

Other adverse environmental impacts of solar panels include pollution and use of hazardous materials. The chemicals used in the manufacturing process vary depending on the make and model of the panel but they generally include PVC and compounds of copper, cadmium, and gallium. Unless these are properly handled during manufacture and are recycled at end-of-life they will contaminate both soil and water.

All companies got worst ratings in the pollution and toxics category so there is plenty of scope for improvement in this area.

Companies did better on other environmental impacts such as water use and waste reduction and nine got middle ratings in our environmental reporting category: GB-Sol, LONGi, Trina, Viessmann, Canadian Solar, Sunpower, Sharp, Panasonic, and REC Solar. The rest got worst ratings.

Are conflict minerals used in solar panels?

As makers of electronics, all our solar companies were rated for their conflict minerals policies. Only Sharp and Panasonic got middle ratings. The rest got worst ratings and lost full marks in the Habitats and Resources and Human Rights categories.

Read our article on conflict minerals to learn more about what they are and where they come from.

Solar Panel Companies

We reviewed and rated 16 companies making solar panels and/or photovoltaic (PV) systems.

There are big ethical differences between the brands. 

One company scores 0/20 points, and several others languishing near the bottom of our score table. 
 

How do solar panel brands score for carbon emissions

We assessed all companies in the guide for their carbon management and reporting. We exempted companies whose only product is solar panels from many of our usual carbon rating requirements because we consider them to be contributing to the climate transition. These companies all got a middle rating by default.

To achieve a best rating, they also had to have a credible and detailed discussion on how they had made emissions cuts in the past and would do so in the future.

Only Canadian Solar and LONGi did this because they had plans to move their operations fully to renewable energy in the next few years.

Companies which make other products were subject to our full carbon rating.

The only one to get a best was Panasonic. Sharp got a middle rating and Viessmann, REC Solar, and Hyundai all got worst.
 

How companies rate for supply chain management

Nearly 70% of the world’s solar cells and modules are made in China. Vietnam comes next with 8%.

Neither are countries renowned for their respect for workers’ rights. Despite publishing long sustainability reports, solar panel companies say little on workers’ rights and as a result all companies got a worst rating in our supply chain management category, apart from GB-Sol which received a best rating.

This is particularly concerning given the use of Uyghur forced labour (see below) and the fact that solar supply chains include large quantities of quartz – the mining of which is linked with silicosis – and which is often sourced from countries with poor workers’ rights regulation.
 

Tax conduct record of solar panel companies

The solar sector did not do well on our tax rating with only GB-Sol, Vikram Solar, Hyundai, and Yingli, getting best ratings – although there was little up-to-date corporate information on Yingli so this rating may not be reliable. LONGi got a middle rating and the rest got worst ratings.

It was notable that three of the Chinese solar companies: Jinko, Suntech, and JA Solar, were headquartered or had parents who were headquartered in the Cayman Islands (on our list of tax havens). Norwegian REC Solar itself got a best rating, but its parent Reliance Industries got a worst rating.
 

Political lobbying

LONGi, Canadian Solar, Sunpower, Panasonic, and REC Solar got worst ratings for their political activity. All lost marks for political lobbying in the US, some for donations to US political parties, and some for membership of the corporate lobby group, the World Economic Forum.

REC Solar did not engage in any lobbying itself but it lost marks through its fossil fuel-producing parent Reliance Industries which spent over half a million dollars on political lobbying in the US in 2022 and over a million in 2021.

Living off-grid

Portable solar panels are a popular choice for generating electricity for people living off-grid or even for just a camping trip.

Apart from Canadian Solar and Hyundai, the solar panel manufacturers in this guide though don’t appear to manufacture portable panels.

Companies that do are quite possibly also riddled with the same supply chain issues that have been discussed here so we urge you to do some research before purchasing.

Additional research for the guide by Shanta Bhavnani.

A domestic solar energy system

Matt Fawcett of Carbon Coop considers what's required for an efficient domestic solar energy system to help save you money and reduce carbon emissions.

If there is one positive we can take from the current energy crisis, it is that higher energy bills will reduce carbon emissions by making energy efficiency and microgeneration more cost effective. A good example of this is the renewed financial viability of domestic solar panels.

What size output of solar panels should you consider?

The cost of the panels themselves has fallen dramatically over the last decade, so they make up an ever-smaller proportion of the overall price, with labour costs having (rightly) increased. It is therefore worth installing a PV array capable of producing more power than the limit on your grid connection e.g. install 4 kW+ of panels for a 3.6 kW grid connection. While your system will ‘clip’ your output at noon in summer, you’ll produce more useful power earlier and later in the day and during other seasons.

Are solar panels viable on east and west facing roofs?

Previously solar panels were only considered viable for south-east to south-west facing roofs, but falling panel prices open the way for east/west installations. While the yield will be lower, the same roof in an east/west orientation has twice the usable surface area compared to a north/south roof (as the north face is unusable).

Many inverters now have multiple inputs meaning you can connect both east and west arrays to the same inverter, making best use of your grid connection for both morning and afternoon sun.

Use more of your own energy

When you sell energy to the grid you'll get a fraction of the price you pay when buying it, so you want to use your own energy where you can. While it’s still hard to justify the financial and environmental cost of home battery storage, if you have a hot water tank, you already have a low-cost, efficient storage medium. Power diverters, such as the Eddi or the Immersun, use excess power to heat water for later use. Their installation is relatively simple and could pay for itself in as little as two years.