The world’s ambition to achieve net-zero emissions has captured rooftop solar’s industry attention, but a silent revolution in the way solar panels’ environmental profile is measured has changed how we view solar energy. Solar has been identified as one of the closest things to a climate solution, and the carbon footprint of solar is no exception—this understanding has changed due to advances in technology, policy changes, and a better understanding of lifecycle emissions. Here are some reasons the numbers no longer add up as they did before.

1. The Unseen Carbon Costs of Solar Manufacturing

While solar panels produce zero emissions when in use, the production of solar panels is energy intensive. Most panels are silicon-based, and studies show that they produce 50–100 grams(low-quality range) of CO₂ emissions per kWh over their lifespan. This is because of mining processes for obtaining raw materials such as quartz and silver and the amount of energy it takes to manufacture the polysilicon used to make solar cells.
However, we are changing the narrative with innovation. Advances in thin-film solar technology and new recycling techniques are reducing emissions. For example, perovskite solar cells (still in research phase) produce 80% less emissions in their manufacturing processes compared to conventional panels. Companies such as First Solar have also pioneered closed-loop recycling techniques to recover 95% of the materials in a solar panel and are reducing waste and embodied carbon by doing so.

2. The Grid Displacement Paradox

One important change is related to how emissions reductions are quantified. For years, we had to demonstrate that the solar panels were located at the premises of customers displacing grid electricity, which in many instances today is coal or gas. As we continue to decarbonize the grid, avoided emissions will become even harder to determine.
For example, in California, where solar adoption is very high compared to the decarbonization of the grid, rooftop systems are displacing natural gas plants, leading to around 30% reductions in emissions from estimates. Conversely, regions like India are still primarily coal-dependent, therefore every megawatt-hour of solar roughly reduces 1,000 kilograms of CO₂, illustrating the variability in geography with solar.

3. “Negative Emissions” Rooftops Start to Emerge

In addition to generating energy, rooftops are also becoming carbon sinks. Vegetated solar canopies or bio-based insulation (e.g. hempcrete) are being implemented to convert panel systems into net-negative emissions systems. For example, a study from the University of Hertfordshire claims that the use of building materials based on hemp cuts embodied carbon by -108 kg CO₂ per m³, allowing the direct emissions of material production for panels to be offset within a decade.
These types of solutions are in-line with circular economic principles. The EU is also promoting and rewarding solar designs that incorporate recyclability and biodegradable materials through their Circular Economy Action Plan; and hopes to achieve emissions reductions of forty percent through lifecycle emissions by 2030.

4. Policy-Driven Emissions Calculations

Government policies are now also changing the calculations. Carbon pricing and renewable energy mandates now apply to Scope 3 emissions—indirect emissions from supply chains. For example, California’s SB 253 law requires large solar developers to report emissions across their entire supply chain, which pressure manufacturers to adopt cleaner practices.

In addition, feed-in tariffs in countries such as Germany have created economies of scale. The costs of solar installation have decreased 80% since 2010, allowing for further adoption, and eventually resulting in lower emissions per unit.

5. The Storage Question

Energy storage systems (ESS) are required to ensure reliability of solar energy—they add another layer to the emissions math. Lithium-ion batteries, which are required for use at night, have a footprint of ~150 kg CO₂ per kWh capacity; however, it is possible that flow batteries and compressed air storage could cut the carbon footprint in half by 2025, creating an even greener profile for net emissions for solar energy.

6. Future Frontiers: AI and Decentralized Grids

Innovative technologies offer the potential of refining the carbon calculations of solar. The AI-optimizing grid assessment evaluates both forecasted weather events and demand on the grid, with the goal to minimize fossil fuel back-up on the grid. In Australia, technology has been able to increase solar penetration by 18%, and reduce emissions of fossil fuels by an estimated 500,000 tons of carbon annually.

Decentralized microgrids with a combination of rooftop solar install and battery are another, promising technology. Decentralized race networks reduce transmission losses, one of the disadvantages of traditional solar, and allow communities to be independent of grid load stations, thus reducing emissions.

Conclusion: A New Equation for Climate Action

The emissions issues of rooftop solar is no longer a matter of determining “clean energy” or “dirty grid.” It involves an interaction of changing technology, create policies, and outdated power infrastructure. As manufacturers develop products and energy storage and distribution networks optimize, the story of solar role as a climate hero will only increase but must be transparent and adaptable to integrate solar input.

Over the next decade, will solar be able to meet its promise of emissions reductions and climate hero? One thing can take place: the math is changing – the world will be looking brighter and cleaner than ever.