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 can reduce the yield to almost zero, are taken into account. The yield is calculated as:
\[ Q_{pv} = \varepsilon_t \cdot \left( I_{diffuse} + I_{direct} \cdot \left(1 - \frac{A_{shadow,active}}{A_{pv,active}} \right) \cdot f \right) \cdot A_{pv} \cdot F_{eff} \tag{1} \]
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 indicating whether 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.
Analogous to this, the nominal yield can be calculated as if no shading hits the area:
\[ Q_{p v} = \varepsilon_t \cdot (I_{diffuse} + I_{direct}) \cdot A_{p v} \cdot F_{p v} \tag{2} \]
This result can be used to calculate the "performance ratio," which expresses how large a yield is possible from an area compared to the actual yield when 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.