Occasionally, Enlighten users notice that their Enphase Battery(ies) are not charging to full capacity, while MyEnlighten shows that production is going to the grid instead of going to the battery.
Normally, you will only see AC Battery charge on the power graph when solar production exceeds consumption. However, you may notice some five-minute intervals where the batteries have charged even though consumption is higher than solar production. This is likely the result of a highly-varying load during a particular five-minute interval.
The power graph shows production and consumption as an average over each five-minute interval. During periods of highly-varying load, there can be moments when when the power produced is higher than the power consumed, causing the batteries to charge. However, the five-minute average of power consumption may still exceed the five-minute average of solar production.
Therefore, while the appearance of the graph indicates unexpected behavior, the actual system behavior is appropriate for the conditions.
For more details, read Why is my battery not charging at full capacity when production exceeds consumption?