For each project was assessed if the guidelines of the Delft Design Approach were systematically applied, and how the application of the guidelines contributed to an efficient and transparent design process.

Table 1 summarises the use of the Delft Design Approach guidelines per project. For the elements that are recommended to be addressed in the process is marked if it was actually addressed in a project.

Table 1. Analysis of design projects

4. Conclusions

From the analysis of the projects, insight was created in how the guidelines of the Delft Design Approach for renewable energy products design were applied in the design process.

Per project there are differences in the approach of the analysis phase. In only two of the projects the Energy Matching Model was used as a guide to structure the analysis. This ensured that all aspects related to the energy chain were addressed. The PV technology analysis of these projects was more transparent than in the other projects. It is remarkable that after studying the Energy Matching Model, the designers adjusted the model to tailor it to their way of dealing with the design of a PV powered product.

The depth of the analysis showed differences as well. The more the designer learned about PV technology application, the better he/she could structure the design and explain to others how the final design developed. A better understanding of the issues involved in PV technology application affected transparency and efficiency of the design process.

Energy matching in the anaylsis phase can be considered a of the synthesis phase for the PV system of the product. Technical possibilities are explored and conclusions are drawn for the overall design of the product.

In two projects the PV solar energy system of the product was fully defined in the analysis phase of the project. As a result the Energy Matching Model and Figure of Matching were not used in the subsequent design phases. The other projects used the Energy Matching Model as a means to generate ideas and to evaluate ideas and concepts in terms of energy matching.

Another project in which the Energy Matching Model was not used in all design phases was the BALL light project. In this project PV technology application was hardly addressed. This may be explained by the fact that the feasibility of PV application for the product was already clear.

For energy matching calculations all the designers made a spreadsheet. Each spreadsheet was different in its use of formulas, input variables and output. A standardised calculation guideline and generic spreadsheet for PV powered product design can be valuable for a designer. The designer will save time, will have a spreadsheet that is understandable for others and can be used by others. Mistakes in the spreadsheet formulas, due to lack of experience of the designer, can be avoided. It is not expected that calculation guidelines can be used by designers without some basic knowledge in PV technology application, due to the specialised nature of the subject.

The designers did not do Figure of Matching calculations; only used the examples presented by Kan [2].

A product benchmark as recommended in the Delft Design Approach was done in only two projects. A product inventory was done en all projects The product inventories were meant to gain insight in the market, while with the benchmark also technical and user-product interaction issues related to the products were analysed.

This paper addressed the research question how young product designers deal with the application of PV technology in consumer products and to what extent they make use of the Delft design approach for the creation of successful PV powered products. The analysis indicates that the designers use many of the guidelines of the Delft Design Approach and the application of these guidelines seem to contribute to transparency and efficiency in the design process. In order to improve the practice of PV powered product design, further integration of the guidelines and tools for teaching material and textbooks is desirable. More knowledge on PV powered product design is also needed as technology development in this area develops very quickly. In the Design for Sustainability and Delft Design Institute program as well as in the Northern Solar Alliance program of the Cartesius Institute more attention is needed for integral design of PV powered products.

References

[1] J. Buijs, R. Valkenburg, (1997), Integrale productontwikkeling, Lemma, Utrecht

[2] S. Y. Kan, (2006), Energy Matching: Key towards Design of Sustainable PV Powered Products, Doctoral Dissertation, Delft University of Technology, Delft.

[3] M. R.M. Crul, J. C. Diehl (2006), Design for Sustainability — A practical approach for Developing Economies, UNEP.

[4] A. Stevels, (2007), Adventures in EcoDesign of Electronic Products 1993-2007, Delft University of Technology, Delft.