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jm0278 avatar image
jm0278 asked

Using Grid Setpoint to Force Charging?

I have a Mulitiplus-II, Cerbo GX running ESS, and some solar. I also run my own control program on a separate computer that communicates with the Cerbo's ESS and can programmatically change parameters based on state-of-charge and time-of-day.

I want my batteries to have a minimum state-of-charge before the grid's peak power rate starts. If I don't get enough solar power to recharge to the minimum before the peak rate starts, are there any issues with raising the Grid Setpoint value to force charging from the grid by setting it higher than the AC load? I just ran a simple test and confirmed I can force charging, but I want to check to see there's a better way or any potential negative consequences to doing so.

Thanks!

Multiplus-IIESS
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marcve avatar image marcve commented ·

@jm0278. Quote: I want my batteries to have a minimum state-of-charge before the grid's peak power rate starts ? Don't you mean, you want them charged before the power gets cexpensive, so you can run your loads of battery during peak hours.

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jm0278 avatar image jm0278 marcve commented ·
That's essentially correct. I try to use only solar to charge the batteries, but when there isn't enough sunlight, I'll pay the lower rate to charge the batteries from the grid then use battery power when the grid rate is high. But I don't need the batteries to be fully charged to get through the four-hour-long peak rate period. The minimum state-of-charge to get through the peak rate period plus enough to cover for a grid failure is 67% state-of-charge. So when paying to charge the batteries from the grid, I only charge them to the 67% minimum needed.
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2 Answers
marcve avatar image
marcve answered ·

I approach your setting in a different way. Always keep my batteries charged. During "expensive" feed, I only take max of 1 amp ( minimal from grid ) from the grid, the rest from solar. During "cheap" hours, I open the AC input, but it will still use the PV available to charge the batteries before it is using the grid.

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jameswest answered ·

Wouldn't you be better off changing the ESS mode to 'keep batteries charged' when your SoC and time conditions are met?

I think someone previously posted a feature request to have this functionality added to a scheduled charge. At the moment scheduled charge will achieve what you want but it continues to power from the grid even when SoC is reached.

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