We’ve been doing a lot of thinking and research on how we source our solar panels here at Big Solar Co-op and we wanted to share some of our work with you.
The unspoken assumption until recently has been something like this: solar panels are intrinsically a super-green technology because they replace generation which would otherwise come from fossil fuel power plants. The energy used to make them is miniscule compared to that which they produce during their lifetime. There is not much to choose between different panel sources – the differences are around quality, longevity and efficiency.
When we started Sharenergy 12 years ago we felt we were still making the case for solar PV as a serious technology and anything that complicated the narrative didn’t get a lot of attention. It’s fair to say that many solar advocates are more or less still following this logic.
These days solar is no niche pursuit – the global value of the industry is in the hundreds of billions. Like any huge transnational industry it has its dark corners of which we are becoming more aware. As champions of environmental and social justice and active participants in that industry, we have an obligation to understand the issues and act on our findings.
There are two main areas of concern – the carbon footprint of solar panels and the social conditions of their production. For us the crucial question is – are some panels better than others? Which ones? How much better?
In this series of three blog posts we will be examining the issues and possible solutions in more depth. We’ll start with carbon. We call ourselves a carbon-first organisation. Can we walk the talk in our choice of solar panels?
Carbon
Establishing the carbon footprint of solar panels is not a simple business. As a bare minimum you need to consider embodied carbon in manufacturing and transport. There are lots of additional factors as well – the other kit needed to connect panels to rooftops, the ground or the grid, competing uses for rooftops and land, end-of-use impacts. In order to make a comparison you have to understand what other generation you are actually displacing too – in the UK it’s mostly gas, sometimes still coal, but in the future it could potentially be other renewables.
Our research to date suggests that one of the most important differences between panels are the carbon emissions involved in manufacture. There are 4 key stages of solar panel manufacturing. Firstly, polysilicon is made from sand or quartzite. Then it is made into an ingot and sawn into wafers. The wafers are made into solar cells. Finally the cells are assembled into a solar panel.
Two thirds of the energy is consumed in the first two stages so it’s here that the use of clean electricity is most crucial. It comes as a shock therefore to find out what fuel is mostly being used to generate the electricity. Coal.
Coal fuels 62% of the electricity used for solar PV manufacturing
Special Report on Solar PV Supply Chains, International Energy Agency
That’s a damning statistic – coal is one of the very worst fuels from a carbon perspective.
It’s also an average. There’s good reason to believe that solar panels vary very widely in their carbon footprint. At the dirty end, a reported 45% of solar polysilicon comes from the Chinese region of Xinjiang – where electricity is virtually all generated by coal. At the other end of the scale other manufacturers carry out these energy-intensive stages using innovative processes using less energy, or use electricity derived from cleaner sources – gas, or renewables. We estimate that solar panels may vary in their carbon footprint by as much as a factor of 5.
The key word here is ‘estimate’. There is a bewildering lack of reliable data available in the public realm. Given the importance of solar technology in global decarbonisation, you might imagine that rigorous lifecycle analysis was available for any solar panel on the market. At least you’d expect to see the sort of Environmental Product Declarations (EPD) that are used in the building industry and widely available for materials from plasterboard to wall plugs.
Unfortunately these documents are incredibly sparse in the solar industry. Consultancy Wilmott Dixon published a study looking at the carbon footprint of solar in February 2022.
The study depends on EPDs from only 3 manufacturers. The authors weren’t being lazy – most manufacturers simply don’t publish the data. Our own research has only turned up a handful of these documents, and some of those look sparse at best. On the crucial issue of embodied carbon during manufacturing, they generally just point to figures given in official Chinese Government guidelines which are generic rather than specific to that supply chain.
In other words, the carbon footprint of solar panels is not being seen as an important differentiating factor in the wider solar market. That’s quite an astonishing conclusion to us.
From our research so far it looks as if even the ‘dirty’ panels are better than the UK’s current grid average from a net carbon reduction perspective, and therefore much better than generating electricity from gas. But there is clearly an opportunity to maximise carbon savings by choosing the greenest solar panels. The impact of that choice is hard to quantify but it could easily amount to a doubling of decarbonisation, which would be enormous.
In the absence of hard data, how do we make a choice?
One approach is to look for manufacturers who have committed to power their operations with 100% renewable energy. Giants like Longi and Jinko appear on the high-powered RE100 global corporate renewable energy initiative list alongside Apple and Google. That looks exciting but we’re treating this with some caution. Firstly, these are future commitments rather than current reality. Longi are aiming for 100% renewables by 2028. How close are they to this now? The list does not say. We’re also bearing in mind that these solar manufacturers don’t actually make the whole solar panel from beginning to end. A manufacturer of solar panels could legitimately claim to power ‘their operations’ from 100% renewable energy sources but be buying their polysilicon from a supplier largely powered by coal.
The approach we are taking is instead to seek to source panels from manufacturers who are showing leadership on the sourcing problem matched with real quantifiable progress. Our first panels will come from Meyer Burger. After many years making solar manufacturing equipment for others, Meyer Burger started their own production in 2021. Their modules are produced in Germany using 100% renewable energy. Their polysilicon is sourced from Germany and Norway.
These panels are very high quality and around 20% more expensive than comparable products. They do have a very low degradation rate which over time compensates for much of the added cost, but here at the Big Solar Co-op we are taking a conscious decision to pay more for panels which we believe have a significantly lower carbon footprint.
There are a number of other reasons to support European-made panels. Reduced transport emissions are an obvious plus. However for us the big one is the set of social issues around the production of panels, from basic worker rights up to serious human rights concerns.
We will be examining these issues in more depth in the next blog post in this series. The third blog will examine some of the more creative ways we are looking to reduce our environmental and social impact even further.