Received an Error Message: R749.0 "120% rule" the combined total of the main breaker and power production source(s) exceeds 120% of the busbar's rating.
Error Message Received:
Typical Causation:
This error is usually caused by the combined total of your main breaker's rating and the continuous output of your power production source(s) exceeds 120% of one of your inputted busbar's rating. It's important to note that the error can stem from any busbar that has been added to the application, not just the service panel.
An Example:
Consider the following example where a user had designed a system where the combination of energy storage and PV was too large for the service panel that was described.
Explanation
In this case, the error occurred because both the PV and the energy storage system output OCPD were 40 amps each, while the backfeed capacity of the service panel was only 40 amps total.
PV 40 amps + ESS 40 amps = 80 amps needed.
Potential Solution(s)
As a solution, if the inputs are accurate, below are a list of potential solutions:
- the installation of a smaller solar energy system; or
- a power control system can be utilized; or
- a main breaker downsize; or
- a service panel upgrade.
Once determined, the SolarAPP+ inputs should be adjusted accordingly.