question

peterb avatar image

Only discharge battery when grid power is above certain threshold

Starting this year, our peak usage will be monitored and taxed. In the summer, PV can recharge the batteries fully and there is no issue. However, in the winter, the batteries do not get fully charged and I would like to configure them so they are only used when peak usage is detected.

What I would like to do is to have the battery only discharge when power usage is above a certain threshold, let's say 2000 Watts.

By manipulating the AcPowerSetPoint (grid setpoint) via MQTT I can create something close to what I want.

I set the grid setpoint at 2000 watts and the battery will only discharge if usage is over 2000 watts. However, this also means that if the usage is less than 2000 watts, it will charge the battery. This is not what I want.

I can continuously monitor the usage and adapt the grid setpoint, but if that process fails, it could mean the battery fully charges, which is not supposed to happen and could be costly.

Is this my best option or are there other ways of implementing this?

batterygridMQTT
2 |3000

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1 Answer
Murray van Graan avatar image
Murray van Graan answered ·

Hi @PeterB you could set the system to keep batteries charged, and then set the AC input current limit to a lower value - roughly 9 amps for 2000W if it’s a 230V system. The system will then try to stay below the 9A threshold, and will start discharging the battery when your usage exceeds that

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Thanks for the tip! I will test it out later this week.