TY - JOUR
T1 - Geographic dependence of the solar irradiance spectrum at intermediate to high frequencies
AU - Bel, Golan
AU - Bandi, M. M.
N1 - Publisher Copyright:
© 2019 authors. Published by the American Physical Society.
PY - 2019/8/16
Y1 - 2019/8/16
N2 - Temporal fluctuations in the solar irradiance are important for renewable-energy harvesting, as well as for climate and ecological-systems analysis. Environmental studies usually focus on slow fluctuations of the solar irradiance, assuming that fast fluctuations are averaged out, while studies of solar power generation emphasize the role of faster fluctuations, due to their effect on grid stability. Several analyses have reported a power-law dependence of the generated-power spectrum for frequencies ranging from 1/min to 1/year. However, both the origin of this power law and its geographic dependence are not fully understood, an issue of significance when one considers smoothing of solar-photovoltaic-power fluctuations by combining geographically distributed generation sources. Here we show that the power law appears in the global and direct components of the solar radiation and not only in the generated power. We also show that the exponent of the power law has a clear latitudinal dependence. At most locations, the spectral power-law dependence of the intermediate (1/day1/h) frequencies. Using a simple model, we explain the origin of the power-law spectra and the latitudinal dependence. The implications of the power law for photovoltaic power generation and grid stability are discussed. We also suggest that the analysis of solar power generation should consider the power spectrum of the clear-sky irradiance at the location of interest in order to separate atmospheric effects from geographical ones.
AB - Temporal fluctuations in the solar irradiance are important for renewable-energy harvesting, as well as for climate and ecological-systems analysis. Environmental studies usually focus on slow fluctuations of the solar irradiance, assuming that fast fluctuations are averaged out, while studies of solar power generation emphasize the role of faster fluctuations, due to their effect on grid stability. Several analyses have reported a power-law dependence of the generated-power spectrum for frequencies ranging from 1/min to 1/year. However, both the origin of this power law and its geographic dependence are not fully understood, an issue of significance when one considers smoothing of solar-photovoltaic-power fluctuations by combining geographically distributed generation sources. Here we show that the power law appears in the global and direct components of the solar radiation and not only in the generated power. We also show that the exponent of the power law has a clear latitudinal dependence. At most locations, the spectral power-law dependence of the intermediate (1/day1/h) frequencies. Using a simple model, we explain the origin of the power-law spectra and the latitudinal dependence. The implications of the power law for photovoltaic power generation and grid stability are discussed. We also suggest that the analysis of solar power generation should consider the power spectrum of the clear-sky irradiance at the location of interest in order to separate atmospheric effects from geographical ones.
UR - http://www.scopus.com/inward/record.url?scp=85072014948&partnerID=8YFLogxK
U2 - 10.1103/PhysRevApplied.12.024032
DO - 10.1103/PhysRevApplied.12.024032
M3 - Article
AN - SCOPUS:85072014948
SN - 2331-7019
VL - 12
JO - Physical Review Applied
JF - Physical Review Applied
IS - 2
M1 - 024032
ER -