Is solar energy truly sustainable?
- Editorial Team SDG7
- 6 days ago
- 4 min read
I’ve often heard solar power described as the golden child of the clean-energy revolution. Panels glinting under the sun, silently generating electricity, promise a future without fumes or fossil fuels. Yet beneath that gleaming surface lies a question we rarely ask, just how sustainable is solar energy when we account for its entire life cycle, from the mines to the recycling plant?
Mining for sunlight
To build a solar panel, we first have to dig deep. Silica sand, silver, copper, lithium, aluminium and cobalt are all essential ingredients. While silicon, the backbone of the photovoltaic cell, is abundant, purifying it demands extremely high temperatures and a hefty dose of energy. Silver and copper extraction can pollute soil and waterways, and lithium or cobalt mining, mostly in South America and Africa, has been criticised for draining water resources and, too often, exploiting labour.
Technological advances are starting to ease the pressure. Recycled metals, lower-silver designs, and alternative materials are slowly finding their way into production lines. But the truth remains, solar is not free of mining scars.
The manufacturing footprint
Producing a solar panel isn’t an emissions-free process. Still, the energy “payback time”, the period a panel needs to generate the energy used in its manufacture, has shrunk to just one to three years. After that, every ray of sunlight is a net gain.
By comparison, fossil fuels never repay their debt. They continue to emit throughout their lifespan. Nuclear has a low operational footprint but carries the burden of construction and waste. Wind, meanwhile, often rivals or even beats solar in carbon efficiency, though it relies on rare earths such as neodymium.
When the sun sets on a panel’s life
Most panels last between 25 and 35 years. Then comes the tricky part, disposal. Some contain trace amounts of lead or cadmium, which can be hazardous if left to rot in landfills. Recycling facilities exist, but the economics are still shaky. Only a small fraction of old panels are currently recycled.
The European Union has begun to address this, setting rules for proper recovery of glass, silicon and metals. Circular design, building panels that can be dismantled and reused, is fast becoming the new frontier.
The numbers behind the shine
Energy source | Emissions (g CO₂/kWh) | Environmental impact | Dependence on critical materials |
Coal | 820 | Extremely high | High (but abundant) |
Natural gas | 490 | High (methane leaks, emissions) | Medium |
Nuclear | 12–20 | Low CO₂, high waste | High (uranium) |
Wind | 10–15 | Low | Medium (neodymium, steel) |
Solar PV | 20–50 | Low to medium | High (silicon, silver, lithium) |
Even accounting for its material needs, solar remains among the cleanest sources of power. The challenge now is to make it cleaner still.
Towards a truly sustainable sun
Three priorities will determine whether solar becomes fully sustainable:
· Ethical sourcing, ensuring miners are treated fairly and ecosystems are protected.
· Higher efficiency, producing more electricity from less material.
· Circularity, designing for disassembly, repair and recycling.
The decade ahead, the science of progress
Between 2025 and 2030, the solar industry will refine silicon technology and introduce new hybrid cells. Panels made with TOPCon or heterojunction designs could reach 23–25% efficiency, while bifacial modules, those that capture sunlight from both sides, will increase generation by another 5–15%. Copper will gradually replace silver, cutting both costs and carbon.
By the early 2030s, perovskite–silicon tandem cells may move from laboratories to rooftops, promising over 26% efficiency at lower production temperatures. The test will be longevity, can they last three decades under the elements?
2030–2040, circular panels and cleaner factories
Looking further ahead, perovskite tandems could dominate, pushing efficiency close to 30% while being easier to recycle. Factories powered by renewables will dramatically shrink their footprint. Panels will be designed for recovery rather than disposal, and recycling silicon and metals will become standard practice.
Solar integration will spread beyond rooftops to farms, car parks and building façades. The future will be less about vast solar farms and more about solar everywhere.
The shrinking carbon footprint
The carbon cost of solar power is already modest and falling fast.
Year | Dominant technology | Average efficiency | Estimated footprint (g CO₂/kWh) |
2025 | Optimised silicon | 22–24% | 20–50 |
2030 | Silicon + bifacial | 24–26% | 12–25 |
2035–2040 | Tandem perovskite–silicon | 28–30% | 8–15 |
By the late 2030s, solar could match or even outperform wind and nuclear in carbon terms, leaving gas and coal far behind.
The road ahead
The future of solar isn’t just about brighter panels but smarter systems, factories powered by renewable electricity, panels designed for easy recycling, and global supply chains held to higher ethical standards.
If current trends hold, solar energy will soon move from being merely “clean in use” to sustainable in its entirety, from mine to module to recycling plant. It will stand as a cornerstone of the global transition towards affordable, low-carbon power, advancing both SDG 7 (Affordable and Clean Energy) and SDG 12 (Responsible Consumption and Production).
We’ve long looked to the sun for light. In the coming decades, we may finally learn to use it without casting a shadow.