Based on the project results Fraunhofer ISE together with the partners DLR and PSE performed a technology comparison between Linear Fresnel-Collector (LFC) and Parabolic Trough (PT) for a 50 MW solar power station. Due to the lower collector efficiency (cosine, shading and blocking losses) of the LFC a larger aperture area is needed than for the PT. For optimized optical and thermal performance it seems completely feasible that due to lower investment costs per aperture area the levelised electricity costs (LEC) for the LFC are appreciably lower than for the PT.

We have calculated break-even-costs for the LFC against a Eurotrough collector with assumed specific costs of 275 €/m2. As can be seen from Figure 8 careless optical design and lower quality components should be avoided due to the economical sensitivity for a variation of optical efficiency. Thermal losses should be lower further which is possible with increased concentration ratio, lower emissivity or

vacuum receivers. In previous studies e. g. [1] specific investment costs of 117 €/m2 for the LFC were compared to 220 €/m2 for PT, resulting in lower LEC for the Fresnel technology consistent with this new comparison. The question, whether for the Fresnel technology lower O&M costs which are a relevant parameter for LEC may be expected is still under discussion.

5 Summary and Outlook

The influence of optical quality on the energy and cost performance requires a careful control and optimization of the collector components. We have developed methods to characterize the key optical components as well as single components as in overall collector performance. All these methods are quite flexible and can be used — with necessary adaptations — also for other concentrating optics. The results obtained so far from different Linear Fresnel Collectors showed were positive concerning optical concentrator quality.

Looking at the results and the large impact of optical quality, thermal losses, tracking and O&M on the economics of concentrating collector in solar power applications, it seems justified and necessary to build a complete solar power plant using Fresnel technology to prove expectations on electricity price. Smaller projects are under way meanwhile.

6 Acknowledgements

The authors gratefully acknowledge the financial support for the research and development projects »FRESQUALI« and »FRESNEL2«, funded by the German Ministry of Environment, Nature Conservation and Nuclear Safety (BMU) under the numbers FKZ 16UM0079 and FKZ 16UM0050.

7 References

[1] Haberle A., Zahler Ch., Lerchenmuller H., Mertins M., Wittwer Ch., Trieb F., Dersch J., The Solarmundo line focussing Fresnel collector. Optical and thermal performance and cost calculations. Proceedings of the 11th SolarPACES International Symposium, (2002)

[2] Mertins M., Lerchenmuller H., Haberle A. Geometry Optimization of Fresnel-Collectors with economic assessment, 5th ISES Europe Solar Conference, EuroSun2004 (2004)

[3] Bernhard R., Laabs H.-G., de Lalaing J., Eck M., Eickhoff M., Georg A., Pottler K., Morin G., Heimsath A., Haberle A.: Linear Fresnel Collector demonstration on the PSA Part I — Design, Construction and quality control, Proceedings of the 14th SolarPACES International Symposium, Las Vegas, USA (2008)

[4] Bernhard R., Hein S., de Lalaing J., Eck M., Eickhoff M., Pfander M., Morin G., Haberle A.: Linear Fresnel Collector demonstration on the PSA Part II — Commissioning and First Performance Testing, Proceedings of the 14th SolarPACES International Symposium, Las Vegas, USA (2008)

[5] Heimsath A., Bothe Th., Li W., Tscheche M., Platzer, W.: Characterization of Optical Components for Linear Fresnel Collectors by Fringe Reflection Method, Proceedings of the 14th SolarPACES International Symposium, Las Vegas, USA (2008)

[5] Morin G., Dersch J. et. al.: Bewertung der linearen Fresnel-Kollektor-Technik und technisch-wirtschaftlicher Vergleich mit Parabolrinnen-Kollektoren, Teilbericht Projekt Fresnel II, Freiburg (2008)