Dear researchers, many researchers in the energy fields fulfill their lack of renewable energy resources data from databases (NREL and NASA, SWERA etc.). But these data sometimes deviate (show more error when compared) from locally actual measured data? Do you think these data is worth for published research and/or actual implementation?
yes ofcourse u can keep trust. it is 20 years average data of renewable resources. details description is written in website and read it
Be careful while using satellite based data unless they have been varified with ground based data. Ground based data are more reliable and hence they shoul be preferred.
Dear all thanks for the contribution.
@ S K Samdarsh, if the satellite data should be verified with the ground data, what would you do when you don't have it as this is the case in many places of developing countries?
@ Sujoy Barua, do u think the satellite data is trust worthy for they have 20 years data archive? I have read the techniques they use to measure the different resource data, some of them is at high resolution, others at medium and low resolution and infact we can't call it "measurement" since it is not direct measurement but it is estimation by taking certain atmospheric quantities and I think it is very liable to error, don't you think?
you are right Mr. Samuel, but you cannot get ground data all around, it is difficult if there are no any research option or measurement instrument . so comparably it is better to do research. even you cannot get certain value so average data and data with some error considerable.
You can use for modelling purpose provided the obtained model is validated properly. Otherwise, only satellite-based data is not acceptable. Recently, one student got resubmission in his PhD viva.
It depends on the objective of the research work and the locations you want to study, as data availability and reliability varies from place to place. If you are at preliminary screening level, for potential locations, capacities and so on, and without good quality data to start with then satellite data can be good starting point. The model can be validated afterwards with actual data. In addition, errors and deviation from actual data can be minimized by conducting sensitivity analysis.
In most cases you can be comfortable using the remote sensing data for sizing solar systems, because (i) it is reasonably accurate; (ii) ground-based data also has uncertainty; and (iii) uncertainty in energy resource data is only one of the error sources when sizing a system - there are others such as simplifications in the sizing method, real energy demand - so there is no point in having very precise resource data if the other necessary data does not have the same degree of accuracy.
However, there are a few situations when remote sensing may not be enough: sizing systems with significant inertias and hysteresis; concentration systems (beam radiation has much more uncertainty than global radiation); places with microclimates, large seasonal variation of ground albedo, or/and where the obstructions of the horizon are very large.
I think you should be cautious in using these data especially for tropical climatic conditions, most of the models for generating climate data are based on sinusoidal changes in weather conditions as experienced in temperate climates, the sinusoidal changes in tropical climate conditions is not a single sine wave over the year. The data is still useful you just need to understand the dynamics of the climate you are investigating and therefore comment on the limitation of the data in this climate.
Dear Samuel
I believe that we can trust data resources such as NASA and NREL for modelling renewable energy systems because the data provided is obtained from weather stations and geostationary satellites for more than 20 years of experience in some cases. However, be careful, there are some sites which provide inaccurate data.
This is a link to an easy and trusted software for accurate irradiation data.
http://meteonorm.com/en/
Kind Regards and Good luck
hi dear,
as far trust concerns, you can trust satellite data and consider the %age error they mentioned for different parameters. you can use satellite data for theoretical calculations.
For modelling with software, you have to check the supported data for that program. again consider the % error of program and data. Then you have to validate your model with some experimental system. Then you can have confidence on your research work.
you can have TMY or EPW data if available, these are validated standard data sets but some of these also contains errors. it all upon the process you use to validate and compare your inputs and results.
Dear Samuel
The answers provided by the contributors are very reasonable regarding your question. Additionally, satellite data can be trusted to a high extent been that they are obtained over a long period of time.However, the data can still be treated as approximate pending validation before any inference can be made.
Dear participants,
I am so grateful for the valuable comments you have provided. I've come to realize from your answer that it is an important issue that should be clarified, the uncertainties in using these satellite data should be known for the betterment of the research as well as application quality in the design of alternative renewable energy systems.
I totally agree these data have paramount importance in the preliminary design stage, but for their uncertainty traits, they should be validated first with ground data if available before going to practical application.
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