Solar heat collectors: Resources and labour
Glass, metal and water, and jobs mostly in China
What this tab covers The natural resources (land, water, materials, fuel or feedstock) and the labour needed to capture this energy, per unit, with the reason each is needed.Solar heat needs roof or land area, glass, metal absorbers, insulation and water for storage, but no rare materials. Estimates of employment range from about 318,000 (2023) to 591,000 (2024) jobs, mostly in China.
Natural resources
| Resource | How much | Why it is needed |
|---|---|---|
| Roof or land area | About 1.4 m2 of collector per kWth (inverse of the 0.7 kWth per m2 convention)6 | Heat output is proportional to the sunlit absorber area. |
| Glass | Over the whole collector; low-iron glass transmits 0.91 of sunlight against 0.84 for standard glass1 | Glass admits sunlight but blocks the infrared radiated by the absorber and keeps out wind; tubes also hold the vacuum. |
| Copper, steel, aluminium and polymers | No per-kW quantity in the sources used2 | Copper conducts heat into the fluid; steel and aluminium make frames and tanks; polymers and aluminium are replacing copper and steel to cut costs. |
| Selective coatings | Absorptance above 0.9, emittance below 0.21 | Absorbs nearly all sunlight while radiating little heat back. |
| Insulation | Mineral or glass wool rated above 200 C; polyurethane foam only below 130 C1 | Collectors left without flow get very hot, so insulation must survive high temperatures. |
| Water for storage | From household tanks to 26,600 m3 pit stores3 | Water stores much heat per kilogram and is cheap. |
Labour
| Phase | How much | Skills | Why it is needed |
|---|---|---|---|
| All phases | About 318,000 jobs and EUR 13.9 billion turnover (2023, IEA SHC); 591,000 solar heating and cooling jobs in 2024, 421,000 of them direct jobs in China (IRENA and ILO)38 | Glass and metal manufacturing, plumbing, roofing, heating engineering | Work is in making collectors and tanks and fitting them; estimates differ in scope and method. |
| Installation | No per-MW figure; small water-heating and combi-systems are about 60% of annual installations5 | Plumbers and roofers in small local firms | Domestic systems are fitted one roof at a time. |
| Operation and maintenance | No figure in the sources used2 | Heating technicians | Systems need proper maintenance to perform over their life. |
Sources
- Solar Collectors (workshop lecture, W. Weiss, AEE INTEC) Centre for Renewable and Sustainable Energy Studies, Stellenbosch University, 2013
- Solar Heat for Industrial Processes: Technology Brief E21 IRENA and IEA-ETSAP, 2015
- Solar market trends in a nutshell (Solar Heat Worldwide 2025 webinar, M. Spork-Dur, 24 June 2025) IEA Solar Heating and Cooling Programme / AEE INTEC, 2025
- Solar Heat Worldwide 2023 edition: Global Market Development and Trends 2022, Detailed Market Figures 2021 (Weiss and Spork-Dur) IEA Solar Heating and Cooling Programme / AEE INTEC, 2023
- Technical Note: New Solar Thermal Statistics Conversion (reference collector parameters, 0.7 kWth per m2) IEA Solar Heating and Cooling Programme, 2004
- Renewable Energy and Jobs: Annual Review 2025 (Table 1 and p. 35) IRENA and ILO, 2026