Hi Waqar,
You do not write into the SET_ACTIVE_POWER_L1_EQUALS,… channels directly if you implement an Ess. They are write only and used only by controllers. What you have to do is to implement the applyPower()-method. See this post: ESS that can talk with OpenEMS using Modbus TCP - #4 by stefan.feilmeier.
Best regards,
Thomas