In recent years, the widespread adoption of photovoltaic (PV) installations across various sectors has created a growing demand for accurate PV design tools. In this pursuit, the latest version of IDA Indoor Climate and Energy (IDA ICE 5 beta) emerges as a contender, offering advanced PV modeling capabilities, together with the advanced building simulation capabilities it already has. This study evaluates the accuracy of PV modeling within IDA ICE by comparing predicted power outputs to real-world data from three existing PV systems located at the Research Institute of Sweden (RISE) in Borås. To achieve this, weather files are created using historical weather and radiation data. As the measured radiation data is only available as total irradiation on a tilted plane, it was deconstructed into direct and diffuse components on the horizontal plane using a modified version of the model by Erbs et al.. Additional known parameters are the geometry of the PV array, and the characteristics of PV panel and inverter, based on their product data sheets. The accuracy of the PV design tool in IDA ICE is evaluated by comparing the power output of unshaded arrays against the measured data from RISE. The calculated power output is compared to the measured power output and analyzed through ASHRAE 14-2014 guidelines for performance evaluation. It was found that the software gives an accurate prediction of both panel temperature and PV power production. A study on shading effects is an open problem to improve the generality of the results in this study.

Accurate separation of global tilted irradiance (GTI) becomes importantwhen the measured irradiance is used for quality control or PV simulationpurposes, for which the latter often requires global horizontalirradiance (GHI), or diffuse and beam irradiance fractions. This studypresents an evaluation of irradiance reverse transposition and separationmodels for the application with GTI in high latitudes. The evaluationis made based on measured and quality controlled six-second irradiancefrom latitude 59.53°N, containing GTI at 30°, 40°, and 90° tiltangles, as well as GHI and diffuse horizontal irradiance (DHI). Basedon a literature review, two specialized GTI reverse transposition andseparation models - GTI-DIRINT and Perez-Driesse - and four GHIseparation models were chosen for evaluation. The latter were testedin an optimization loop developed for this study that utilizes existingGHI separation models combined with transposition models for reversetransposition and separation of GTI. Specifically, the separation modelsErbs, Skartveit1, Engerer2, and Yang4 were tested with Hay &Davies and Perez1990 transposition.The models were investigated using both statistical evaluation metricsand Diebold-Mariano test to compare measured and predicted GHI and DHI. An evaluation with measured data showed that for GTI reversetransposition and separation at high latitudes, the use of the proposedoptimization model with Engerer2 in combination with Hay & Daviestransposition, or the Perez-Driesse model is recommended. This isbased on overall good ranking and low bias of GHI prediction with -2.0W/m2 and -2.3 W/m2, respectively.