Dish concentrators paired with Stirling engines
A parabolic dish concentrates sunlight to a focal point where a receiver is coupled to a Stirling engine. The concentrated heat causes a working gas in the Stirling engine to expand and contract, driving pistons that turn a generator to produce electricity.
Why the dish-Stirling pairing is efficient:
- High concentration ratios: the small focal area allows very high temperatures and thermal efficiency.
- External combustion engine: the Stirling engine runs on heat without internal combustion, which simplifies emissions control and allows efficient heat-to-power conversion.
- Modularity: units are compact and suitable for distributed generation.
Operational points:
- Dual-axis tracking is required to maintain focus on the small focal spot.
- Efficiency gains come with higher temperatures but require durable materials and precision engineering.
- Maintenance and cost need to be managed; historically, dish-Stirling showed high efficiency but faced commercialization challenges due to cost and reliability.
Dish-Stirling systems remain attractive where high-efficiency small-scale solar generation or remote, off-grid power is needed.