As the Internet of Things (IoT) nodes become one of the cornerstones of Industry 4.0, they tend to be incorporated into every aspect of production automation. This paper addresses the challenge of designing low-power IoT nodes based on standardized components for deployment in remote, off-grid, industrial, and hazardous environments where energy efficiency and autonomy are critical. The proposed design integrates hardware-software co-design, replacing standard hardware setup with energy-efficient components, solar-powered batteries, and dynamic working modes to reduce energy consumption. Software elements were designed with the possibility of over-the-air updates and reconfiguration. Next, battery charging routines are optimized, and the node is integrated into a cloud-based digital twin with centralized control over the complete operation cycle. The proposed node architecture achieves an energy reduction of up to 50% and, in some configurations, reduces consumption by up to one-tenth compared to conventional designs. The additional result is a set of design recommendations when the standard components must be adapted for harsh environments.