Time-of-Use (ToU) pricing shifts energy demand to times of day when energy is more affordable. Often, it is these times when clean and renewable energy is abundant. To get more consumers to join ToU pricing, researchers have tried using voluntary (opt-in) enrollment and mandatory (opt-out) enrollment (with the choice to leave). They found that voluntary enrollment is catastrophically lower than mandatory enrollment, which nears 100%. While mandatory enrollment has a high participation rate, it does not equal willing compliance; instead, it leaves consumers feeling powerless and may erode trust in the utilities. When utility providers use opt-out enrollment following Procedural Justice Theory (PJT), it may improve the fairness of process and shape legitimacy in the consumer's eyes. Utility providers can apply PJT by justifying their mandatory enrollment process to the consumer. This study tested different justifications head-to-head in a mandatory enrollment ToU context (environmental, reliability, equity vs control) to identify which justification frame increases willingness to participate and perceived fairness, something no research has yet tested. This study used a between-subjects experiment of randomly assigned college students to 4 conditions. Participants read a ToU enrollment scenario with frame-specific justification or control, then rated procedural fairness perceptions and willingness to participate. Utilities benefit from scalable, evidence-based guidance on which justification preserves trust while maintaining enrollment, enabling sustainable renewable energy integration through willing consumer participation.