question

elvis avatar image
elvis asked

ESS Feed-in Limiting causes MPPT to be erratic. Is it Normal?

Multiplus II 12/3000/120-50 2X-120V

SmartSolar Charger 150/35 (4 100W panels in series)

SmartSolar Charger 100/20 (Single 250W panel)

BMV 712

400Ah LifePO4 Batteries (X2 200AH in parallel)

CerboGX

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ESS Feed-in Limiting causes MPPT to be erratic.

Battery charging MPPT's are pretty smooth and maxed out.

As soon as the battery is full, Feed-in is active and the MPPT's become erratic.

Is it normal? Maybe the inverter trying to calculate proper sync values?

mppt-ess-feed-in.png


Here is another example with limiting turned on

mppt-ess-feed-in-full-day.png


Example with limiting turned off

chart-export5.png

MPPT ControllersESSgrid
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1 Answer
elvis avatar image
elvis answered ·

Well, It would seem the issue is related to the Limit Feed-in setting.

I had it set to 700W. This is well above a normal achievable output value. I only set it that high in the hope it might limit a spike that sometimes happens and the battery supplies 6 7 or 8 hundred watts to the grid for several seconds. Typical feed-in during full sun is less than 500W. Even tho this feed-in limit value is rarely seen, the fact that it is "Set" has the weird effect of oscillating / pulsing the feed-in power. If I set it to 1000W its no problem. So My question is...What is the limit value actually a limit of?

I figured it would be the actual value being feed in. But that does not appear to be the case.


Any ideas?

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