You didn't give all parameters so we could actually recreate your numbers, but it's a simple explanation so you'll have no trouble doing it yourself.

You can just read up on this in the Engineering Reference. For a Simple Model, the power output is calculated as ^[1] :

$$P = A_{surf} \cdot f_{active} \cdot G_{T} \cdot \eta_{cell} \cdot \eta_{inverter}$$

Where:

• $A_{surf}$ is a surface area in m2 from Generator:Photovoltaic > Surface Name and $f_{active}$ is the PhotovoltaicPerformance:Simple > Fraction of Surface Area with Active Solar Cells. Eg: in your case if your surface is 100 m2 and given that 87.52% of it is covered with solar cells, the product would give 87.52 m2 of actual PV panels.
• $G_{T}$ is the Total solar radiation incident on PV array [W/m2] (only parameter in this equation that is calculated by E+)
• $\eta_{cell}$: the efficiency from PhotovoltaicPerformance:Simple
• $\eta_{inverter}$: the inverter efficiency, eg from ElectricLoadCenter:Inverter:Simple

^[1] Source: Engineering Reference: Photovoltaic Arrays: Mathematical description