Subtasks
The objectives shall be achieved through the following four subtasks,
with proposed subtask
leaders and activities indicated:
Subtask A: Solar Resource Applications for High Penetration of Solar
Technologies
(SUNY/Albany, USA: Richard Perez)
This Subtask will develop the necessary data sets to allow system
planners and utility operators to understand short-term resource
variability characteristics, in particular up and down ramp rates, to
better manage large penetrations of solar technologies in the grid
system. Although this work is primarily focused toward PV systems, which
react almost instantaneously to cloud passages over individual panels,
the information is also useful for solar thermal and CSP systems where
intermittence resources can impact their ability to meet load demands.
The following activities will be undertaken to assure that the
objectives of this task are met:
Activity A-1: Solar variability, and specifically ramp rates,
for particular systems (lead: Hans Georg Beyer). Specific high-frequency
(10-min or less) solar data sets will be obtained through third party
sources and will be analyzed to provide statistical characteristics of
solar ramp rates for solar systems of various sizes.
Activity A-2: Spatial and temporal characterization of
intermittency (lead: Richard Perez). In this activity, the combination
of spatial and temporal variability of solar resources will be evaluated
either from ground networks or from high spatial-resolution 15-minute
satellite data (downscaled to 1-minute sampling rates). This will
improve our understanding of cloud decorrelation characteristics and the
effects of dispersed solar systems on aggregate system
output under various cloud climates.
Activity A-3: Integration of solar with other RE technologies
(lead: Lourdes Ramirez Santigosa). Although hybrid systems are often
considered for optimal renewable energy electricity production, hybrid
systems can also be used for heating in combisystems such as
using biomass with solar heating. Technical requirements for grid
integration depend on grid conditions, which will also be addressed in
this activity. Ultimately this activity could include microgrids, but
not at the start of the task. The focus of this activity is on weather
data and irradiance data.
Activity A-4: Spatial and Temporal Balancing Studies of the
Solar and Wind Energy Resource. This Activity includes the following
elements: 1) The evaluation of the spatial balancing of the solar
resource (both GHI and DNI)) across various distance scales; 2) The
evaluation of the spatial and temporal balancing of both the solar and
wind resources across various distance scales, and 3) Based on the
eventual existence of a spatial balancing, the eventual improvement of
the solar radiation forecasting associated with this balancing.
Subtask B: Standardization and Integration Procedures for Data
Bankability
(lead: DLR, Germany, Carsten Hoyer-Klick)
Activity B-1: Measurement best practices. Manuals on best
practices for obtaining measured data sets that provide “bankable” data
for financial institutions will be prepared.
Activity B-2: Integration of data sources. This activity
explores procedures of combining different data sets, such as short-term
ground measurements with long-term satellite-derived data, for
extrapolating quality ground data to longer-term climatic data sets,
allowing for longterm cash flow analyses of projects.
Activity B-3: Evaluation of the use of TMY data. In this
activity, the historical use of TMY data will be evaluated in the
context of current best practices for simulating solar system design and
output. Recommendations for alternative approaches to TMY data will be
made, given that TMY data sets do not allow for evaluation of extreme
high= and low-resource events.
Activity B-4: Data uncertainties over various time frames.
This activity documents the importance of data uncertainty for data sets
representing various time frames in ways that the risk in financing a
project can be quantified.
Activity B-5: Gap-filling, QC, and Flagging. This activity
documents best practices in filling missing data gaps, conducting data
quality control, and flagging potentially erroneous data values when
creating an archive of a database.
Subtask C: Solar Irradiance Forecasting
(Elke Lorenz, U. of Oldenburg, Germany)
Activity C-1: Short-term forecasting (up to 3-days ahead):
co-leads: U of Oldenburg (Elke
Lorenz) and SUNY/Albany (Richard Perez). This activity tests and
benchmarks forecasting
procedures covering three distinct time scales:
- Forecasting from observations (0-6-hours):
- NWP and mesoscale models (1-3-day ahead)
- Integration of measurements with models for
0-24-hour ahead
Activity C-2: Integration of solar forecasts into operations
(Lead: CENER, Lourdes Ramirez Santigosa). This activity examines the
important issue of how solar forecasts are used in utility operations. A
critical aspect of this task is to seek input from utility operators on
the specific types of irradiance or power output forecasts they would
like to have in order to improve system operations and reduce the
overall cost of energy and maximize the use of renewable energy within
the system. Another important point of this activity is related to the
knowledge of the different electricity markets and to improve
understanding of the influence of forecast in the final energy sale.
Activity C-3: Long-term variability and impact of climate
change of solar resources (Lead: NASA, Paul Stackhouse). In this
activity, studies of long-term solar data sets, both observed as well as
satellite derived, will continue to asses episodes of “global dimming”
and “global brightening”, important for evaluating potential long-term
cash flow implications from solar systems. Efforts will be undertaken to
link the results of IPCC climate change scenarios to predictions of
future solar resource variations.
Subtask D: Advanced Resource Modeling
(NREL: Manajit Sengupta)
Activity D-1: Improvements to existing solar radiation
retrieval methods (Lead: GEOModel, Tomás Cebecauer). A number of input
parameters and modeling approaches to development of satellite-derived
solar resource data sets will be examined, including:
- Direct/diffuse irradiance (Aerosol Optical Depth, or
AOD, is important here)
- Spectrally-resolved irradiance
- Angular distribution of irradiance
- Atmospheric parameters (AOD)
- Enhanced cloud parameters, including 3-D cloud
characterization
Activity D-2: New modeling approaches (Lead: NREL, Manajit
Sengupta) This task will evaluate the latest products coming out of the
U.S. National Oceanic and Atmospheric Administration, such as the GOES
Surface Irradiance Product, which offers a promising solution for
providing near real-time irradiance values throughout the western
hemisphere at 4-km resolution.
Activity D-3: Development of global solar resource data sets
for integrated assessment of global and regional RE scenarios modeling,
with a special focus on CSP and solar heating technologies (Lead: DLR,
Carsten Hoyer-Klick). This task examines approaches for determining
global renewable energy potentials, in particular global potentials, for
use in renewable energy scenario modeling. The Activity also looks at
the impact of up scaling fineresolution data into courser global grids,
to see if the removal of subgrid variability introduces biases to the
answers.
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