Another approach would be to use Sense export with Excel to accumulate Total Usage vs. Solar Production. Pretty easy to do with Pivot Tables. The most manual parts of the process would be filtering for the range you want, plus gluing multiple exported files together, since export range is fixed to calendar months and years.
A couple pointers in Excel - Use the Pivot Table function on the dowloaded daily usage file from Sense. Configure the Name field into the Pivot Table columns and remove all but the Total Usage and Solar Production entries.
Configure Months DateTime and DateTime into the Pivot Table rows. Sum the kWh field.
Then select one of the data entries in the new Pivot Table and go to the Value Field Settings form. From there you can choose to see the results in Running Total form. Here I have done it by month, but if you add a Billing Month field to the original downloaded spreadsheet, that coincides with your billing months, you can get a running total in custom billing months.
