What must not allow a section of a solar energy system to be isolated from a relief device?

A section of a solar energy system must not allow isolation from a relief device by means of valving off because a relief device is crucial for maintaining safe operating pressures within the system. If a section is valved off, it can prevent the relief device from functioning effectively. Should pressure build up in that isolated section, it could lead to potentially dangerous conditions, such as system failure or even rupture.

Relief devices are designed to protect the system from exceeding specified pressure limits. In the event of overpressure, the relief device must be able to engage and release excess pressure. If valving off creates a situation where the relief device cannot operate correctly, then the safety mechanism is compromised, increasing the risk of damage or injury.

In essence, avoiding isolation through valving is necessary to ensure that pressure control systems remain operational, thereby safeguarding the entire solar energy setup from catastrophic failures due to excessive pressure conditions.