Task V: Solar Resource Knowledge Management

Nature of Work and Objectives

The goal of the IEA ‘Solar Resource Knowledge Management’ Task is to provide the solar energy industry, the electricity sector, governments, and renewable energy organizations and institutions with the most suitable and accurate information on the solar radiation resources at the Earth's surface. These data should be easy to access, understandable and high-quality. The scope of solar resource assessment information includes historic datasets and currently derived data products using satellite data and atmospheric modeling.

The three main objectives to be achieved in this Task are to:

• Provide further standardization and benchmarking of international solar resource data sets,

• Provide improved data reliability, availability and accessibility in formats that address specific user needs, and

• Develop methods that improve the quality and spatial and temporal coverage, with customized solar resource products, including reliable solar radiation forecasts.

Better data accessibility and standardization will shorten the time needed for planning. More accurate and more detailed information on solar irradiance helps improve solar energy system efficiency and allows it to be adapted to the irradiance characteristics of specific sites. Forecasting will increase the value and acceptance of the solar energy produced.

Scope of the Task

This task focuses on the development, validation, and access to solar resource information derived from satellite-based platforms and surface-based stations. It will define standards for intercomparison of irradiance data with respect to energy applications. Various quality control procedures for solar irradiance time-series will be reviewed and if possible improved. Benchmarking of solar resource products against reference measurements will help the user to better identify uncertainties and select products which are sufficiently reliable. The Task examines means by which the data can be made easily available to users through various web-based hosting schemes and distributed networks. Further, options for forecasting solar radiation in various time-scales from hours to several days will be developed. Past and future climate variability of the solar resource will be investigated to estimate the uncertainty of solar yields.

Organization and Structure

The objectives of Task V will be achieved through task-sharing activities defined in a coordinated work plan. Work is carried out by participants from 17 institutions in 7 countries and the EU. In 2006, Austria became a new member by contributing with a project on solar radiation forecasting through the Solar Heating and Cooling Implementing Agreement (SHC). The work plan is structured in three subtasks:

Subtask A: Standardization and Benchmarking of
Solar Resource Products

The main goal of this Subtask is to ensure worldwide inter-comparability and acceptance. This covers:

a)       Coherence and benchmarking of models producing solar irradiance values from satellite data.

b)       Accessibility and coherence of ancillary model input data such as atmospheric conditions and land-surface parameters.

c)        Sensitivity analyses.

d)       Ground truth validation with high-quality data.

e)        Definition of validation protocols and measures of end-product confidence.

f)          Cross-satellite platform and cross-model comparisons

Subtask B: Common Structure for Archiving and
Accessing Data Products

The objective of this Subtask is to provide a user-oriented information system, such as a distributed data system, for archiving and accessing solar resource data. Key subtask activities to meet this objective are:

a)    Evaluate the Legal Aspects of Accessing Solar Resource Data: This activity focuses on establishing copyright and proprietary rights for data that is to be made available through the distributed data system, and to establish appropriate protocols with each participating institution for making the data generally available to the public.

b)    Identify commonly-used software by end users: This activity examines available or needed software for use by industry and other users to access the information system.

c)    Develop data exchange protocols and metadata: Various data exchange protocols will be examined and one will be selected and documented.

d)    Develop a prototype data networking procedure: A prototype web-based system will be developed whereby a user can request information of a certain type and format, and the information system provides the response or responses that most closely fulfill the request.

e)    Identifying resource providers: A worldwide network of data providers will be set up, and the techniques for data exchange among the providers will be investigated.

f)     User prototype testing: This activity defines a prototype that can be accessed by users, and increases awareness of the data-exchange system among external users.

g)    Define automatic access by commercial applications: This activity will enable fast, automatic access of resources through the information system by using commercial applications.

h)    Develop a ‘solar micro-siting’ test application: A case study in micro-siting of a solar energy system will be developed to demonstrate the benefits of the information system.

Subtask C: Improved Techniques for Solar Resource Characterization and Forecasting

The purpose of this Subtask is to conduct essential R&D to improve the accuracy and spatial and temporal coverage of current techniques, including the introduction of solar resource forecasting products. Key activities to meet this objective are:

a)    Improve Satellite Retrieval Methods for Solar Radiation Products: This activity will focus on key model input parameters and methodologies, such as cloud indices, radiative transfer schemes, aerosol data retrieval, and treatment of snow and other surface albedo artifacts. The activity also addresses ways of improving the spatial resolution of satellite-derived broadband solar resource products.

b)    Climatological analysis of solar resources: to ascertain future impacts on system performance due to climate variation, this activity includes the analysis of long-term surface and satellite-derived data sets and climate models, specifically addressing natural long-term fluctuations associated with the ocean-atmosphere system, such as the Southern Oscillation/El Niño.

c)    Forecasting of solar radiation: This activity investigates different approaches for developing solar resource forecasts based on global numerical weather predictions and extrapolation of cloud motion vectors from satellite data.

Collaboration with other IEA Programs

Knowledge of solar resources is highly important for all forms of solar energy applications. Therefore, SolarPACES Task V is an IEA collaborative task working with the Solar Heating and Cooling (SHC) and Photovoltaic Power Systems (PVPS) Implementing Agreements. The SHC ExCo coordinates the ‘Solar Resource Knowledge Management Task’, where it is called SHC Task 36. Collaboration with SolarPACES and PVPS is kept at a ‘minimum level’ according to the SHC ‘Guidelines for Co-ordination with other Programs’.

Duration

The Task began on July 1, 2005 and is planned to continue until June 30, 2010.

ACTIVITIES DURING 2006

Second Experts Meeting

Following the First Experts Meeting held at DLR in Oberpfaffenhofen, Germany, in November 2005, a Second Experts Meeting was held in Denver, Colorado on 7-8 July 2006, just before the Solar 2006 Conference which was held at the same location. 12 experts, plus two more participants by video conference, attended the meeting, representing all the participating countries except Spain. Each subtask leader led detailed discussions on ongoing activities and plans within their subtask. There were additional discussions regarding the relationship of the Task to the Global Earth Observing System of Systems (GEOSS) Program, the Global Energy and Water Experiment (GEWEX) Program of the World Meteorogical Organization (WMO), and the UNEP (United Nations Environmental Program) Solar and Wind Energy Resource Assessment (SWERA) Program. A key outcome of the meeting was a clearer focus on critical subtask activities leading to modifications to the Task Work Plan. Following the meeting, many of the task participants gave presentations in three related sessions at the Solar 2006 Conference organized by the American Solar Energy Society (ASES).

Data User Questionnaire

During 2005, a Data User Questionnaire was developed and issued to gather key information on data requirements. It aims to find out how industry, government agencies, universities, and others are using available solar resource data, what the shortcomings are and which additional products are desired. Results of the survey will be used as input for the design of the information system (Subtask B) as well as for some of the products coming out of all the Subtasks. During the transition to the new SHC website currently under preparation, the JRC in Ispra, Italy has agreed to support the Task’s website at http://re.jrc.cec.eu.int/iea-shc-task36. It is hosting the questionnaire and other related documents.

Collaboration with the Group on Earth Observations

The G8 countries came to the conclusion that Earth observation by satellites and surface-based measurement networks require better worldwide collaboration. To improve the situation, they initiated the Group on Earth Observations (GEO), which will be setting up the Global Earth Observation System of Systems (GEOSS) in the coming years. GEOSS combines the effort of space agencies, weather services and other environmental monitoring services. Most activities are strongly user-oriented and will be guided by what are called ‘Communities of Practice’. One of these is related to requirements of the energy sector. Renewable energy applications are known to receive huge benefits from Earth observation activities, but fossil fuel energy applications also recognize advantages. Thus, the GEO Energy Community of Practice serves all energy applications.

Task participant Marion Schroedter-Homscheidt of DLR was appointed Co-Chair of the GEO Energy Community of Practice. On August 28-29 2008, she attended the Energy Management Experts Meeting at the WMO in Geneva, Switzerland. Although there is currently no formal relationship between the IEA and the GEO, collaboration of the Solar Resource Knowledge Management Task with GEOSS appears to be advantageous. The IEA Task can advise this Community of Practice. The GEOSS solar energy sector is closely aligned with the scope of the IEA Task. Many ideas from the IEA Task’s Work Plan, e.g., the user questionnaire and roadmapping, are serving as examples for other energy sectors. Results like those of the IEA Task’s questionnaire will be submitted to the GEO Board of Ministers in November 2007 as a contribution to the GEOSS Strategic 5-10 year plan.

New Subtask C Leader: