Supply chain networks in the photovoltaic sector were faced with a rapid decline in prices during the past few years, which is predicted to go on in the following years. These circumstances force related companies to coordinate production, distribution and transportation planning of all their network sites thoroughly. Moreover, continuous-time scheduling of processes is required to determine times of sales exactly within a multi-day planning horizon. Applying this type of scheduling is possible due to assessable price trends and existing framework agreements with wholesalers, and even necessary due to its impact on the realized sales prices, and thus, the network profit. For this reason, we develop a mixed-integer linear programming model that meets the requirements of fully-integrated photovoltaic supply chains that cover processing of raw materials, manufacturing of intermediate and finished products in two alternative methods, and selling them on international markets. The multi-product approach enables to connect supply chain stages with different product maturities. The modeling is motivated by a real-life case of a global photovoltaic group headquartered in Germany. As it was not possible to optimize this problem with high-performance software and hardware within 3 months, we tested several relax-and-fix decomposition methods. By selecting those algorithms that were able to generate high-quality solutions within acceptable computation times of less than half a day, a satisfying solution was found. The appropriateness of the selected algorithms is additionally demonstrated by analyzing randomly generated scenarios in a numerical study.

中文翻译：

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价格下降的光伏供应链生产，分销和销售的连续时间计划

在过去的几年中，光伏行业的供应链网络面临着价格的快速下跌，预计在接下来的几年中这种情况还将持续下去。这些情况迫使相关公司彻底协调所有网络站点的生产，分配和运输计划。此外，需要连续的流程计划来确定确切的销售时间（在几天的计划范围内）。由于可评估的价格趋势和与批发商的现有框架协议，因此可能应用这种类型的计划，甚至由于其对实际销售价格以及网络利润的影响，甚至有必要应用这种计划。为此原因，我们开发了一种混合整数线性规划模型，该模型可以满足完全集成的光伏供应链的要求，该模型涵盖了原材料加工，两种替代方法的中间产品和最终产品的制造，并在国际市场上销售它们。多产品方法可将具有不同产品成熟度的供应链阶段连接起来。该建模是基于总部位于德国的全球光伏集团的真实案例进行的。由于不可能在3个月内使用高性能的软件和硬件来优化此问题，因此我们测试了几种松弛固定修复方法。通过选择能够在不到半天的可接受计算时间内生成高质量解决方案的算法，找到了令人满意的解决方案。