Investigating methods to improve photovoltaic thermal models at
second-to-minute timescales
Abstract
This paper presents a range of methods to improve the accuracy of
equation-based thermal models of PV modules at second-to-minute
timescales. We present an RC-equivalent conceptual model for PV modules,
where wind effects are captured. We show how the thermal time constant
τ of PV modules can be determined from measured data, and
subsequently used to make static thermal models dynamic by applying the
Exponential Weighted Mean (EWM) approach to irradiance and wind signals.
On average, τ is (6 .3±1 .0) min for fixed-mount PV
systems. Based on this conceptual model, the Filter- EWM - Mean Bias
Error correction (FEM) methodology is developed. We propose two thermal
models, WM1 and WM2, and compare these against the models of Ross,
Sandia, and Faiman on twenty-four datasets of fifteen sites, with time
resolutions ranging from 1s to 1h, the majority of these at 1 min
resolution. The FEM methodology is shown to reduce model errors (RMSE
and MAE) on average for all sites and models versus the standard
steady-state equivalent by −1 .1K and −0 .75K
respectively.