Case Study

Protective Relay Design

Client Type
Project developers
Project Type
Engineering & design

When developers install solar + storage systems, utilities may require that the storage systems are disabled when the solar is exporting using a utility-approved relay system.


HRE has designed and spec’d a specific utility-approved relay scheme that many storage developers have used to ensure that the storage system is disconnected when the solar is exporting and the storage attempts to discharge, but allows for normal operation otherwise.


A utility-approved relay system that allows the developer to acquire Permission to Operate (PTO) from the utility despite the mix of exporting and non-exporting generation assets.

Additionally, HRE typically employs Schweitzer Engineering Labs or Basler protective relays for this scheme. HRE designs the the full low voltage control system and programs the relays using the manufacturer software. HRE partners with several testing agencies to provide third party bench test reports and third party on-site witness tests, both required by utilities prior to PTO.