The ReliaHome Smart Panel is a residential energy management system designed to optimize and dynamically control the home's highest consumption loads, saving homeowners money on their energy bill. This solution allows for adding large electrical loads, such as vehicle chargers, without the need of incurring costly service and panel upgrades. For solar and storage application, it can extend the battery runway getting the most out of your backup system. Lastly it is compatible with any load center and backup storage system. With advanced features and unmatched reliability, it is the perfect solution for all electrical distribution equipment needs. The ABBHEMT1 PUK is a valuable accessory designed to complement the ABBHEM2 ReliaHome Smart Panel for specific solar + storage systems. While it is not always required, it is essential for certain backup systems that take more than 70 ms to transition, as it provides ride-through voltage to the ABBHEM2 during such transitions. This accessory is necessary for all generators and certain inverters. It is not required for Tesla, Enphase, and Franklin systems. This accessory comes standard with the NEMA 3 R (outdoor) design (ABBHEM2 N3 R).