You can add Output:Variable objects to your IDF file to request specific variables. After a successful E+ run, you can open the eplusout.rdd file to see the list of available variables. You can also look at the I/O reference guide to see the variables attached to an object.

For your case, you could request the ones for Generator:Photovoltaic such as Generator Produced DC Electric Power.

The Output:Table:SummaryReports has a predefined monthly report called GeneratorReportMonthly which may include a detail per generator, do try that. For short, you can include all reports:

Output:Table:SummaryReports,
   AllSummaryAndMonthly;  !- Report 1 Name

Edit: I tried with the E+ example file GeneratorsWithPV.idf, and I didn't get a GeneratorReportMonthly report, no matter if I use GeneratorReportMonthly explicitly or AllMonthly... After investigation in the source code, this one is added for cogeneration units, and the variables contained in the report also show that really.

Anyways, ShopWithSimplePVT.idf has some good examples of Output:Table:Monthly reports you can use for PV performance (just paste them into your IDF, and you'll see some new tables in your eplustbl.htm). There are others for inverters etc in that file, do look for them, but the one you'll be most interested in is:

  Output:Table:Monthly,
    PV Performance Summary,  !- Name
    2,                       !- Digits After Decimal
    Generator Produced DC Electric Power,  !- Variable or Meter 1 Name
    HoursNonZero,            !- Aggregation Type for Variable or Meter 1
    Generator Produced DC Electric Power,  !- Variable or Meter 2 Name
    SumOrAverageDuringHoursShown,  !- Aggregation Type for Variable or Meter 2
    Generator PV Array Efficiency,  !- Variable or Meter 3 Name
    SumOrAverageDuringHoursShown,  !- Aggregation Type for Variable or Meter 3
    Generator Produced DC Electric Energy,  !- Variable or Meter 4 Name
    SumOrAverageDuringHoursShown;  !- Aggregation Type for Variable or Meter 4

This is going to create a monthly table for each of your PV generators.