# Spectrally-Selective Energy-Harvesting Solar Windows for Public Infrastructure Applications
## 3 Results
### Principal Results and Future Directions
These V\({}_{\rm oc}\) reductions were expected to lead to electric mismatch losses in the parallel-connected window-module circuits and were likely the reason why the combined Fill Factor of a six-window installation (0.488) was below the average Fill Factor of individual window modules (0.505). The two parallel-connected Unisolar PVL-72 flexible PV modules (rated at 72 W\({}_{\rm p}\) each and covering, in total, 2.24 m\({}^{2}\) of horizontal roof area). Some environmentally-induced contamination was possibly present on top of the active areas of these roof-mounted modules, which might have accounted (together with the weather-related and geometric orientation factors) for some reduction in the measured output of these modules when compared to both the peak ratings and also the expected values. We only observed up to 57.37 W of electric output from the roof-based PV system. Based on this measured electric output accounting for the precise geometric orientation of PVL-72 panels with respect to the incoming sunlight and their peak rating, an estimate of the instantaneous direct-beam solar irradiation intensity can be made, which results in about 752 W/m\({}^{2}\) if any module-area contamination effects or aging-related performance reductions were neglected. Figure 7: Transparent photovoltaic wall of windows installed into a Port Melbourne bus stop powering an advertising display and lighting appliances. Several unframed PV window modules are also shown during factory assembly process at Qingdao Rocky Ltd. (Qingdao, China), which is shown on the left. At 9:30 a.m., near 450 W/m\({}^{2}\) of solar irradiation intensity fell onto the horizontally-oriented surface, according to the published graphs showing the solar irradiation intensities recorded in Melbourne (Caulfield South, [[http://caulfieldsouthweatherstation.com/charts/solar](http://caulfieldsouthweatherstation.com/charts/solar)]([http://caulfieldsouthweatherstation.com/charts/solar](http://caulfieldsouthweatherstation.com/charts/solar)) during the same day). The theoretically maximum radiation intensity falling onto the horizontal roof area would have been (at perfect, AM1.5G peak-weather conditions corresponding to 1000 W/m\({}^{2}\) of direct-beam irradiation intensity) near 1000 W/m\({}^{2*}\)sin (32\({}^{\circ}\)) or 530 W/m\({}^{2}\). Therefore, an estimate for the power scaling factor characterizing the weather-dependent system performance applicable to measurements made on 7 February 2017 can be quantified as W = 450/530 = 0.849. This figure corresponds to 849 W/m\({}^{2}\) of direct-beam irradiation intensity and significantly exceeds the 752 W/m\({}^{2}\) obtained from pure geometry and rated system performance. Therefore, using 849 W/m\({}^{2}\) irradiation intensity can be considered sufficiently conservative for use in our estimates of the peak-weather performance of this PV wall in field conditions especially considering that some hazy clouds were visually observed during our measurements. The atmospheric path length was also greater than the standard atmospheric path at AM1.5 conditions due to the Sun altitude angle being 32\({}^{\circ}\). Figure 8: Measured PV I-V curves of a 6-window vertically-oriented bus-stop wall installation and comparison with a reference PV module output. (**a**) I-V curves of both PV modules measured concurrently in field conditions using PROVA 200A Solar Module Analyzer. (**b**) The corresponding power-voltage curves data. Therefore, ClearVue 6-window vertical PV wall can be predicted to have demonstrated, at peak weather conditions, the approximate power output below. \[\text{P(max, 32}^{\circ}\text{ Sun angle, at 1000 W/m}^{2})=(74\text{W}/0.849)*100=87.16 \text{ W},\]  
where we still have not accounted for any geometric shading effects induced by the overhanging roof section.