Southwest Environmental Limited

Which Solar Panels are the most Sustainable?

To the casual eye the two solar panels look very similar but the technology in side is very different. The one to the left produces electricity, the one to the right produces hot water. But which is best?

Solar PV

Solar PV panels take sunlight and turn it in to Electricity. They are by far and a way the most popular type of solar panel in the UK. Especially where you might see then in large arrays dotting the countryside.

Image: SayCheeeeeese [CC0], via Wikimedia Commons 

Solar Thermal

The answer is that Hot Water is best but only up to the amount you can make use of. If you want extra then  . . . . Electric Photovoltaic Panels. Why?

Image: SolarCoordinates [CC BY-SA 3.0], via Wikimedia Commons

Example - Health Care Development

A hospital in the planning phase needs to outline emissions reductions to the tune of 20%.

17.5% of the building energy demand will come from heating water, for washing and bathing etc. So we can use solar thermal panels for this, generating 700 KWh / pa / m2 we install 48 m2 to provide 17.5% of the buildings energy at a zero carbon rating.

35 m2 photovoltaic panels  meets the remaining 2.5%, as they only produce 140  KWh / pa / m2.

So as a rule maximise hot water panels, and then top up with PV panels. Hot water panels can also be used for space heating if combined with a thermal store of some kind, although heating seasons will be short. Find out why solar panels for hot water are perhaps a better option than solar panels that generate electricity.

The above summary is very generalized, and for a true comparison of which option is the most suitable we would suggest a Life Cycle Assessment of the two panels, taking in to account site specific factors. Of course Life Cycle Assessment is likely not feasible for smaller projects but for large projects or smaller projects that will be repeated, it is worth the effort to find the most sustainable solar panel.

Locations of Solar Farms in UK

Solar farms are large installation of typically Solar PV panels. Although they do use solar thermal technologies occasionally. We have recently produced a map showing locations of solar farms in the UK. It all shows other power generation facilities across the British Isles.

The below section was written by a machine.

Technical Article: Evaluating Solar Panel Sustainability Metrics

As the UK transitions toward a low-carbon energy grid, the deployment of solar photovoltaics (PV) has become a central component of corporate carbon strategies. However, from a technical consultancy perspective, not all solar panels offer the same environmental benefits. To determine the most sustainable option, we must look beyond generation efficiency and examine the "cradle-to-grave" impact of the technology. Southwest Environmental Limited (SWEL) utilizes over 15 years of industry experience to provide the technical data required for these assessments.

Life Cycle Assessment (LCA) of Photovoltaic Systems

A comprehensive sustainability analysis of PV technology requires a detailed Life Cycle Assessment (LCA). This methodology quantifies environmental impacts across several key technical stages:

• Raw Material Extraction: Evaluating the environmental cost of mining silicon, silver, and aluminum, including the energy intensity required for purification.
• Embodied Carbon: Calculating the "carbon payback period"—the time it takes for a panel to generate the equivalent energy used in its manufacture. We use Whole Life Carbon Assessments (WLCA) to verify these figures accurately.
• Manufacturing Operations: Assessing the greenhouse gas intensity of the factory's energy mix, which is critical for panels produced in regions with a high reliance on fossil fuels.
• End-of-Life (EoL) Circularity: A technical review of the recyclability of the panel laminate and the recovery rate of precious metals at the end of the operational lifespan.

Comparative Sustainability of PV Technologies

Modern renewable energy projects typically choose between primary cell architectures, each presenting a distinct sustainability profile:

• Monocrystalline Silicon: Known for high efficiency (20%+) and a long operational life (up to 30 years), which often results in superior long-term carbon displacement despite the higher initial energy intensity of the manufacturing process.
• Polycrystalline Silicon: Generally features a lower embodied energy profile during production but may offer lower efficiency and a shorter effective lifespan compared to monocrystalline alternatives.
• Thin-Film (CdTe/CIGS): Utilizes significantly less raw material and has a lower energy payback time, though the inclusion of heavy metals requires rigorous environmental compliance and end-of-life management.

Professional Authority and Planning Integration

Our technical findings regarding renewable technology are frequently integrated into Sustainability Statements and Energy Strategies to support complex planning applications. As a verified NATO and industrial supplier with a 15-year track record and 900+ projects completed across the UK, SWEL provides the professional accreditation (FGS, MIEnvSc) necessary to validate these environmental claims. Whether you are conducting a renewables options appraisal or developing a Net Zero Roadmap, we provide the evidence-based insight required for sustainable decision-making.