SimPV Theory
In SimPV an estimate of the yield from a building integrated PV system is calculated for a given location on the building model. Shadows striking the solar cells, which will reduce the yield to almost zero, are taken into account The yield is calculated as :
\[ Q_{p v} = \varepsilon_t \cdot \left( I_{diffuse} + I_{direct} \cdot \left(1 - \frac{A_{shadow,active}}{A_{p v, active}} \right) \cdot f \right) \cdot A_{p v}F_{eff} \tag{1} \]
where:
εt is the total efficiency (solar cells, converter, cable-losses etc.) in the solar cell system. The system efficiency can be obtained using SimDb from the materials part of the database in table 9.
Idiffuse is the diffuse solar power on the PV-array.
Idirect is the direct solar power on the PV-array.
f is a factor giving is a part of the face is shaded.
f = 1 if Ashadow ≤ 0 or Ashadow > 0 and PropShadRed (SimDb) = 1,
f = ShadEff if Ashadow > 0 and PropShadRed (SimDb) = 0.
Apv is the geometric area of the solar cell system, defined in SimView with Add PvArray [m²], inside Frame Dist.
Ashadow, active is the shaded area of Apv, active.
Apv is the total area of the solar cell system.
Fpv gives the active part (Active Area) of the area Apv [%] recalculated to a fraction.
Analouge to this, the nominal yield can be calculated as if no shading hits the area as:
\[ Q_{p v} = \varepsilon_t \cdot (I_{diffuse} + I_{direct}) \cdot A_{p v} \cdot F_{p v} \tag{2} \]
This result can be used to calculate the "performance ratio" which express how large a yield is possible from an area compared to the actual yield taking into account losses from shading etc. The calculations are made for each time-step and summarised to monthly values shown in a result log for each face with solar cells.