Against the background of climate objectives and the desired reduction of CO2-emissions, optimization of existing industrial products is needed. To counter rising raw material costs, currently used materials are substituted. This will places new requirements on joining technologies for dissimilar material classes. The main difficulty lies in joining these materials cohesively without changing the properties of the base materials. Current research work at the LZH on joining dissimilar materials is being carried out for the automotive sector and for solar absorbers. For the automotive industry, a laser welding process for joining steel and aluminum without using additives is being investigated, equipped with a spectroscopic welding depth control to increase tensile strength. With a specially constructed laser processing head, it is possible to regulate welding penetration depth in the aluminum sheet, reducing the formation of intermetallic phases. Flat plate solar collectors are favorable devices for generating heat from solar energy. The solar absorber is the central part of a collector, consisting of an aluminum sheet and a copper tube which is attached to the aluminum sheet. Research on new laser welding processes aims at reducing the amount of energy required for production of these solar absorbers. In the field of joining dissimilar materials, laser joining processes, especially for special applications, will complement established joining techniques.