Which type of backup power systems requires significant manpower and monitoring during use?

The correct response points to the portable generator as the type of backup power system that necessitates significant manpower and monitoring during its operation. Portable generators, while versatile and effective in providing temporary power, typically require manual setup and regular oversight to ensure that they are functioning properly, especially in critical applications like traffic signal control.

Using a portable generator involves refueling, monitoring output, and ensuring that connections are secure and safe. This practical engagement can demand more human resources compared to other systems, such as battery backups or uninterruptible power supplies, which can operate autonomously once set up. Additionally, portable generators must be monitored for their fuel levels and any potential issues that may arise during operation, further underscoring the need for continuous supervision and active management.

In contrast, battery backups and uninterruptible power supplies are often designed to operate automatically without the need for continual human intervention. Solar power systems, while they may require some maintenance, typically do not require significant manpower for operation. Overall, the nature of portable generators requires direct human involvement, validating the selection as the correct answer.