Download Building a long-term record of the global solar energy

2017_63: Building a long-term record of the global
solar energy resource from satellite observations
Supervisors: Dr Helen Brindley ([email protected]), Dr Nicholas EkinsDaukes, (Physics); Dr Caroline Poulsen and Dr Matt Christensen (Rutherford
Appleton Laboratory)
Department: Physics
The recent ratification of the Paris Agreement to limit the global average surface
temperature increase to well below 2°C above pre-industrial levels will require a strong
drive away from a carbon driven global economy to alternative energy sources. One
obvious candidate is solar power. However to optimize photovoltaic cell design in order
to maximize power output, the form (diffuse/direct), amount and, for the most efficient
cells, spectral distribution of the solar radiation incident at the surface must be known.
For example, recent work carried out by a Grantham PhD student shows how
inappropriate assumptions concerning the wavelength dependence of incident solar
radiation strongly reduce the power output of a standard multi-junction solar cell.
This dependency leads to a problem since, in many of the regions most suited to solar
cell deployment, there is a lack of ground based measurements of solar radiation.
Even where such measurements exist they are usually limited to broadband (spectrally
integrated) quantities. Satellite observations, used in conjunction with radiative
transfer modelling tools, have the potential to fill these gaps but current approaches
either contain assumptions concerning the underlying atmospheric state or infer this
state from a combination of different instruments using different approaches.
Two variables that exert a key influence on the available solar resource are aerosol
and cloud. Under the auspices of ESA's Climate Change Initiative, scientists at the
Rutherford Appleton Laboratory have developed an algorithm that applies a common
approach to aerosol and cloud retrievals. In addition, these data are used to generate
broadband radiative fluxes, providing a consistent link to the incident solar radiation at
the surface. So far these approaches have been applied to observations from the
Along Track Scanning Radiometer (ATSR) series of instruments, spanning 1995 to
the present day.
The aim of this PhD is to further develop the radiative transfer capability within the
RAL algorithm such that the quantities most pertinent for assessing the solar resource
and informing solar cell design are routinely generated. Once implemented and
evaluated, the dataset will be fed into the SolCore solar cell simulation tool developed
at Imperial College in order to estimate the electricity generation potential for different
For more information on how to apply visit us at www.imperial.ac.uk/changingplanet
Science and Solutions for a Changing Planet
cell designs as a function of location. In this way the optimal cell technology and/or
design for different regions can be identified based on real, long-term observations.
Further directions for the research using the tools developed could include:
• extension of the approach to other suitable satellite instruments potentially providing
greater temporal and spatial coverage
• the assessment of redundancy in the solar spectrum: useful for the design of
simplified, autonomous, ground-based instrumentation to improve the ground-based
network
• the use of the radiative transfer code in ‘off-line’ mode fed by relevant meteorological
output from the next generation of Earth-System models to obtain predictions of the
future solar resource and how this varies with time/climate change scenario
For more information on how to apply visit us at www.imperial.ac.uk/changingplanet