question

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Off grid system. Switching in extra load when SOC 100%

We are designing and off grid system with a solar array though a couple of Smart MTTPs. There is almost certainly a Cerbo GX in the system. During the day when the SOC reaches 100% we would like to be able to send any further solar energy to a simple DC heater. This would need to switch out when the MTTP were no longer exceeding the normal system load.

We hoped to program the Cerbo relay to control a high power relay. Is this possible. Or is there another way. I noted the Cerbo info state "diverts excess (solar) power to self-consumption" but fail to find an explanation.

Many thanks for all contributions

Andy


ESScerbo gxoffgridRelay
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1 Answer
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tozz answered ·

The Cerbo has outputs you can use. Those are not high power relay outputs, but you can use a relay to switch bigger loads.

You can use the "stop/start generator" relay function in the Cerbo to switch your heater. If you set relay 1 to "stop/start generator", you can then configure


"Use battery SoC to start/stop" -> on

"Start when battery SoC is lower than" -> eg 90%

"Stop when battery SoC is higher than" -> eg 98%


You will have to invert the relay's output, but that should be no problem since you'll have t use an external high power relay anyway. The Cerbo's relay are not suitable for high power loads.


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