**6. Conclusions**

A solar collector network is a thermal structure that absorbs solar energy, transforms it into heat, and delivers it to a user. When the user is an industrial process, the operation of the solar plant must be capable of supplying the process thermal needs under the most critical ambient conditions. The thermal design under these conditions fixes the maximum working hours wherein the process thermal requirements are achieved. For operation under more favorable atmospheric conditions, the excess heat collected can be taken advantage of to increase the plant working time. Heat storage can be used to provide a flexible operation. The features of a flexible solar collector network are:


A complete approach to the integration of solar heat into process industries must involve, on the one hand, the detailed design and analysis of the operation of the solar collector plant, and on the other, the specification of the way heat is transmitted to the process. This work covers the design for flexible operation of a solar collector plant.

The design of a thermal plant must specify the total number of solar collectors and its arrangement. The target temperature is achieved by placing collectors in series, while the heat load is achieved by adding lines in parallel. The manipulation of the inlet temperature and the mass flow rate are fundamental to reduce the size of the solar plant. It was shown that significant reduction in collector surface area can be achieved by proper design and this has a direct impact on plant investment.

**Author Contributions:** Conceptualization, G.M.-R., J.R.L.-M. and M.P.-Z.; methodology, G.M.-R. and J.R.L.-M.; software, J.R.L.-M. and A.L.F.-S.; validation, G.M.-R. and J.R.L.-M.; formal analysis, M.P.-Z. and G.M.-R.; investigation, G.M.-R., J.R.L.-M., M.P.-Z. and A.L.F.-S.; resources, G.M.-R.; data curation, G.M.-R. and A.L.F.-S.; writing-original draft preparation, G.M.-R., J.R.L.-M. and M.P.-Z.; writing-review and editing, A.L.F.-S. and M.P.-Z.; visualization, A.L.F.-S.; supervision, G.M.-R.; project administration, G.M.-R.; funding acquisition, G.M.-R. and M.P.-Z.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
