# Sunlight: Impact on nature

Clean while running: where solar's footprint really lies

Source page: https://www.materialinsights.org/energy/e_sunlight/nature/

Clean while running: where solar's footprint really lies What this tab covers What taking energy from this source does to land, water, air and climate, wildlife and ecosystems, with life-cycle emissions and land use where measured.

Solar power emits no greenhouse gases while running; its life-cycle emissions come from making panels: IPCC AR5 medians 41 to 48 g CO2e/kWh for PV, NREL harmonised medians 45 for crystalline silicon and 14 to 26 for thin film. The main local effect is land use.
 Life-cycle emissions 48 (utility PV), 41 (rooftop PV), 27 (CSP) g CO2e/kWh^[12](https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf#page=7) Life-cycle, IPCC AR5 medians; ranges 18-180, 26-60 and 8.8-63. NREL LCA harmonisation (2012) medians: 45 for crystalline silicon PV (57 before harmonisation); 14 (CdTe), 20 (a-Si) and 26 (CIGS) for thin film in a sunny US south-west setting. UNECE 2021 finds 8.0-83 for PV and 27-122 for CSP; the spread reflects panel type, sunshine at the site and the carbon intensity of the factory's electricity. Land use about 2,000 (ground-mounted PV, median); near zero for rooftop ha per TWh per year^[14](https://thebreakthrough.org/blog/whats-the-land-use-intensity-of-different-energy-sources)

#### Effects on nature

| Area | Effect | Size | How it is reduced |
|---|---|---|---|
| **Climate** | Emissions arise mainly from energy used to refine silicon and make panels.^[12](https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf#page=7) | IPCC AR5 medians: 48 g CO2e/kWh utility PV, 41 rooftop, 27 CSP; UNECE 2021 gives 8.0 to 83 for PV across regions and technologies. | Thin-film panels and low-carbon electricity in manufacturing lower the figure. |
| **Climate (harmonised)** | NREL re-ran published PV life-cycle studies on common assumptions to narrow the spread.^[15](https://ideas.repec.org/a/bla/inecol/v16y2012is1ps122-s135.html) | Crystalline silicon median 45 g CO2e/kWh (57 before harmonisation, 42 estimates from 13 studies). | Higher module efficiency and longer lifetimes cut emissions per kWh. |
| **Climate (thin film)** | Thin-film panels need less energy-intensive material than silicon wafers.^[16](https://ideas.repec.org/a/bla/inecol/v16y2012is1ps110-s121.html) | Harmonised estimates for a sunny US south-west site: 14 (CdTe), 20 (a-Si), 26 (CIGS) g CO2e/kWh. | Siting in sunny regions and longer module lifetimes lower the figure further. |
| **Land** | Ground-mounted plants occupy large areas; rooftops use none.^[14](https://thebreakthrough.org/blog/whats-the-land-use-intensity-of-different-energy-sources) | About 2,000 ha per TWh per year for ground-mounted PV; near zero for rooftops. | Rooftops, car parks, degraded land, and combining panels with grazing or crops. |
| **Land (relative)** | Among electricity sources, land occupation per kWh is highest for CSP, then coal, then ground-mounted PV.^[13](https://digitallibrary.un.org/record/4020227) | Regional spread of about 1 to 5 for CSP and 1 to 3.5 for PV, following how sunny the site is. | Siting in high-irradiance regions reduces land per kWh. |
| **Water** | PV uses little water in operation; silicon-based PV needs a moderate amount in cell manufacturing.^[13](https://digitallibrary.un.org/record/4020227) | Far below thermal power plants, which dissipate 0.9 to 5.9 litres per kWh. | Dry or hybrid cooling for CSP; water recycling in factories. |

Solar power has no fuel, no combustion and no moving parts in PV, so its environmental footprint is set at the factory and by the site. Life-cycle emissions are a few per cent of those of coal power and fall as panels become more efficient and factories cleaner.

Land is the main local issue. Solar farms need around 2,000 hectares for each TWh produced a year, but the land is not sealed: vegetation and grazing can continue under and between panels, and rooftop systems need no new land at all. End-of-life panels are a growing waste stream that will need recycling of glass, aluminium, silicon and silver.

#### Sources

1. [Climate Change 2014: Mitigation, Annex III Technology-specific cost and performance parameters (Schlömer et al.), Table A.III.2, p. 1335](https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf#page=7) IPCC AR5 Working Group III, 2014
2. [Carbon Neutrality in the UNECE Region: Integrated Life-cycle Assessment of Electricity Sources (ECE Energy Series 73)](https://digitallibrary.un.org/record/4020227) UNECE, 2022
3. [What are the land-use intensities of different energy sources? (summary of Lovering et al., PLOS ONE 2022)](https://thebreakthrough.org/blog/whats-the-land-use-intensity-of-different-energy-sources) The Breakthrough Institute, 2022
4. [Life Cycle Greenhouse Gas Emissions of Crystalline Silicon Photovoltaic Electricity Generation: Systematic Review and Harmonization (Hsu et al., Journal of Industrial Ecology 16 S1)](https://ideas.repec.org/a/bla/inecol/v16y2012is1ps122-s135.html) NREL LCA Harmonization Project / RePEc, 2012
5. [Life Cycle Greenhouse Gas Emissions of Thin-film Photovoltaic Electricity Generation: Systematic Review and Harmonization (Kim et al., Journal of Industrial Ecology 16 S1)](https://ideas.repec.org/a/bla/inecol/v16y2012is1ps110-s121.html) NREL LCA Harmonization Project / RePEc, 2012

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_sunlight/index.md)
- [Overview](https://www.materialinsights.org/energy/e_sunlight/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_sunlight/correlation/index.md)
- [How energy resides](https://www.materialinsights.org/energy/e_sunlight/resides/index.md)
- [Abundance](https://www.materialinsights.org/energy/e_sunlight/abundance/index.md)
- [Fluctuation in time](https://www.materialinsights.org/energy/e_sunlight/time/index.md)
- [Across the Earth](https://www.materialinsights.org/energy/e_sunlight/geography/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_sunlight/links/index.md)