Say Goodbye to Costly Main Panel Upgrades with EG4's Power Control System

The Canadian Electric Code (CEC) Rule 64-112 (4)(g)(i) deals with the interconnection of power production sources, particularly solar photovoltaic (PV) systems, to the load side of service equipment or a distribution panel. This rule limits the combined current from all power sources to 125% of the busbar’s rating or conductor ampacity to prevent overloading and ensure electrical safety.

To help us out, the writers of the code book, thankfully clarified the rule in the appendix:

Appendix B - Notes on Rules (2024 CEC code book) Rule 64-112 subrule 4)g)

This Item recognizes equipment installed to limit the current on the busbar or conductor to prevent overloading. Consideration should be given to ensure that in the event of equipment failure, the busbar or conductor will not become overloaded. An energy storage system is a load when charging and a source when discharging.

Here are some key points of this rule:

1. It applies to interconnections on the load side of service equipment or distribution panels
   
   
2. The rule allows the total current from all sources (utility + PV) to reach up to 125% of the busbar or conductor ampacity
   
   
3. This 125% limit includes both the main overcurrent device (e.g., main breaker) and the PV system's overcurrent device, installed as far away from the main breaker as possible
   
   
4. The purpose is to prevent overloading of the busbar
   
   
5. Unlike the National Electric Code (NEC) 120% rule in the US, the CEC uses a 125% limit

Therefore, if homeowners wanted to add more solar panels to an existing electrical system, they would typically need to upgrade the main service panel to safely accommodate the additional solar, which can be quite costly!

There is a high chance that a customer will back off from his solar contract if I propose him to upgrade his main panel, as the added labor and cost is upwards of $5,000 for the new panel, says John T, Director of Sales EG4.

Power Control Systems (PCS) to the Rescue

In the US, the NEC recently introduced a new rule, 705.13, which allows the use of Power Control Systems (PCS) to connect to existing electrical panels and dynamically manage and limit the back-fed current on the busbar, without violating the 120% rule, vs. Canada 125% rule - we get an extra 5% due to our cold climate?

Even though Canada has had this rule since the 2021 CEC code book, and further clarified in appendix B of the 2024 CEC code book - section 64-112 subrule 4)(g)(i) the PCS “equipment” was not yet available in Canada. 

Until Now!

The EG4 18kPV, 12kPV and FlexBOSS21 Hybrid Inverters can support ample PV and eliminate costly panel upgrades, as illustrated below.  This means that as your energy needs grow, you can add more solar panels and battery storage to your existing system with EG4.  This is a major innovation that enhances integration and makes solar more financially accessible for homeowners in the US and Canada. 

Sol49 Will Help You With PCS Settings & Warning Labels
EG4 inverters monitor the supply side with CTs to ensure that it will never add more power to the busbar than it can handle. At the time of install, Sol49 will help you with the PCS settings on your EG4 inverter and provide you with the appropriate warning labels for the electrical panel that you’re backfeeding. To stay within the code, the PCS Setpoint will be set at 80% of the busbar value.

Send us a message to learn more about EG4’s PCS systems and pricing at [email protected]

Sources
Naveen Tera, EG4 - Avoiding Costly Main Panel Upgrades