Dear Ahmed,

try these links:

http://re.jrc.ec.europa.eu/pvgis/

http://re.jrc.ec.europa.eu/pvgis/solrad/index.htm

Regards

Thank you Roberto for your response.

I think both links are very interesting, however they do not provide measurements on inclined planes, but they provide simulation data for a clear sky (on horizontal and inclined planes).

My goal is to validate my program, with real measurements performed by measuring devices, such as pyranometers on horizontal and inclined planes at the same time.

And another thing, maybe I forgot to make clear is that the measurements that I want to use must have a wide dynamic equal to one hour or less.

Regards.

Actually, the PVGIS database includes data for both GHI and global tilted irradiance (GTI) on an optimally tilted surface. However, this is _modeled_ data and therefore includes all the shortcomings and errors that are inherent to the models used.

The original question asked for _measured_ data. There are not so many publicly accessible data sources for that. I would suggest those from NREL, UO and IDMP:

http://www.nrel.gov/midc/srrl_bms/

http://solardat.uoregon.edu/SolarData.html

http://idmp.entpe.fr/

Another possibility would be to obtain non-pubic data through personal communication with authors of recent publications on the topic.

Hello Mr. Gueymard,

Indeed, PVGIS may be a first track, and I think the data are interesting. Except that are either monthly, or daily but just an average value over the month. But this possibility of to have the solar radiation on inclined plane is already very interesting to me.

For http://idmp.entpe.fr/ site, I've already started to contact those responsible for the different measurement stations, just after you give me the link last time. and I already had some answers from Mr. Mojtaba Navvab (The University of Michigan).

Thank you again Mr. Gueymard.

These data may help you

http://sonda.ccst.inpe.br/basedados/index.html

Raphael, this database is indeed very interesting, but does not seem to include any measurement on tilted surfaces, which was what the original request was about...

Thank you Raphael for the link,

Unfortunately, as stated Mr. Chris, the site provided just horizontal measurements. Personally this kind of database interest me to consider future research.

Regards.

I am using this: https://eosweb.larc.nasa.gov/cgi-bin/sse/grid.cgi?

they say it is a 22 years monthly average readings, and they include data for inclined surfaces and averages at every hour. However, since they provide the data at any point at earth, just specify the longitude and latitude, I don't believe they did the actual measurements every where and at every angles, I believe they did the actual measurements in many locations at various angles, and correlate the data to to validate satellite scans.

One last remark, solar power at inclined plane can be deduced with a simple geometry calculation knowing the power at the horizontal surface; is this your program?

Ziad, the NASA-SSE dataset is entirely modeled, and the resolution is only 1x1° or about 100x100 km, which is not sufficient over complex terrain. Since that dataset does not contain any measurement, it is not what the original request was about...

Our dataset from Eugene, Oregon has solar radiation on several tilts and horizontal, direct normal, and diffuse measurements. The data can be downloaded from http://solardata.uoregon.edu/SelectArchival.html. Click on Eugene and select the years designed. Depending on the year, 1, 5, 15, hourly or data are available. The instruments are Eppley PSPs for the most part. There is one pyranometer tilted 90 degree north also. That should be the hardest test.

The National Renewable Energy Laboratory MIDC site also has tilted data to go with its measured DNI, DHI, and GHI data.

Good luck with your project.

Sincerely,

Frank Vignola

Indeed Frank... And I had already these links above ;-)

Hello Mr. Vignola,

I find your dataset from Eugene very interesting. Although it is mentioned by Mr. Gueymard but it's been difficult to find. I found very interesting data in the NREL site, mentioned by Mr. Gueymard above: http://www.nrel.gov/midc/srrl_bms/.

I would like to thank you all, for all your very helpful answers, for me and perhaps for others. And a big thanks for Mr. Gueymard for his answers and for his very useful tips.

Again thank you very much. I wish you a very happy new year, full of "reSearch", full of success.

Ahmed Bouabdallah

You can use a hourly global inclined solar radiation database available in the following website :

http://www.soda-is.com/eng/service /services_radiation_free_eng.php

Khalil, I checked http://www.soda-is.com/eng/services/services_radiation_free_eng.php but I don't see any source of _measured_ data there...

Go to the bottom of the page , where it is written "Hour " the in your wright u will find three cases , go to the middle one where it is written " HC3v4hourINCL" click on it and you will go to another page. There , you can choose any place in the world and you will get hourly data for the period between ( Jan 2004- Dec 2005 )

But again, these are entirely modeled data, not _measured_ data!

Look to this website it has measured data

http://wrdc.mgo.rssi.ru/

Take another one

http://geomodelsolar.eu/data/typical-meteorological-year

Http://geomodelsolar.eu/data/full-time-series

The Geomodel data, like HelioClim, is purely _modeled_, so not what the initial question was about.

The WRDC data are measured, but not for _tilted_ surfaces. Such measurements are done for research purposes only, and thus not by normal meteorological networks, hence only a few stations in the world have done that, or still do that.

One potential source of measured data for tilted surfaces is the IDMP project. Its purpose was for illuminance, rather than irradiance, but some of the research sites also had tilted pyranometers.

See http://idmp.entpe.fr/

yes it is a general problem for us whom work in the solar radiation estimation and modelling , for all of my works in this field the big problem is the measured data , so i hope that every one put databases to facilitate the work

Best regards.

Hi khalil,

Thank you very much for your response, and for the links. I find them very interesting, but once again as he replied Mr. Gueymard, the need was :

1) > data

2) on inclined planes

and in the same time

3) on horizontal planes.

I think the best sites that grouped these kinds of measurement are (mentioned above by Mr. Gueymard and Mr. Vignola) :

http://www.nrel.gov/midc/srrl_bms/.

http://idmp.entpe.fr/ and

http://solardata.uoregon.edu/SelectArchival.html.

Again, thank you khalil for your answer.

Ahmed Bouabdallah

Hi Ahmed,

Another way to get irradiance data is a bit more cumbersome: Most measurements on a tilted plane are carried as part of the monitoring of PV systems. To get to such data you will have to find papers and reports on such projects, write the authors and beg for data. Then you will have to deal with different data formats, time conventions, error flag conventions and quality issues. Good luck!

Hi Jethro,

All first Thanks for the suggestion. I want to add, just that it is difficult for someone to share with you his measurement, especially if such measurement are made ​​with a personal effort and I can understand that. But note, I contacted several authors and they (some) have give me what they can give me, and I thank them a lot.

I think the websites that we have cited, along this discussion is very interesting for all perssonnes working around the topic of renewable energy (particularly: solar and wind). and personnaly I'm going to finish my paper on this subject based on these sites.

Cordially.

Hi Ahmed,

I did write that it was cumbersome ;-).

Dear Ahmed Bouadballah,

There are some high quality tilted measurements in the NREL MIDC database. We also have some in our data base at http://solardata.uoregon.edu/SelectArchival.html for the Eugene station. We do have some tilted data with our PV sites, but these are measured with Li-Cor pyranometers.

Another tip:

The following paper analyses the monitoring data of 21 European PV systems

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.115.4656&rep=rep1&type=pdf

If you could get hold of their data you would have a large uniform quality checked dataset in one go. Co-author Ulrike Jahn is now working at TÜV Rheinland. See: http://www.iea-pvps.org/index.php?id=61for contact details.

More generally, I think this thread illustrates that it would be very helpful for many researchers if there would be an open access data base of worldwide PV monitoring data. Of course, this is not trivial. Defining standards for quality checks, formats, carrying out the checks and bringing the data in this format would take a lot of work and would have to be funded somehow. Another issue is than many projects have been carried out by, or in co-operation with, commercial parties, who mostly like to keep the data to themselves. But it is nice to dream...

I am also looking for such data to validate transposition models. However, there is not much available I think. I attended the BSRN-Meeting in 2012 and I was asking if tilted measurements could be included in the BSRN. The reaction was positiv in general, but there is no funding for such measurements. I still think, BSRN would be a nice option as measurement uncertainties can be quite high for solar radiation measurements (especially compared to the deviations of tilted models reported in the literature) and BSRN standards would asure high quality. Daily cleaning of the sensors, recalibration, etc would requires high effort for separate measurement, but only some more effort within BSRN.

I completely agree that it would be nice to have tilted measurements at BSRN stations. However, this kind of measurement is mostly for solar applications, whereas BSRN is mostly for climate and atmospheric research. Funding for fundamental solar radiation measurements applicable mostly to solar applications will probably remain limited until the rapid development of solar energy becomes officially recognized as one essential component of climate change reversal.

NREL just completed a study where it used CM22 pyranometers to measure global and tilted irradiance for a year at three separate sites (Eugene, Oregon, Florida Solar Energy Center, and Golden, Colorado. This was part of NREL's project to validate PV performance models. Bill Marion at NREL is heading up the project.

I'm eager to see the results of that study!

I'm eager to see the results of that study!

Hi,

Firstly, you can use a simple pyranometer for measuring the perpendicular solar radiation. Then the correlations of tilted surfaces in the following books will lead you to calculate the inclined radiation:

1- "Renewable Energies", by: da Rosa

2- "Solar Energy Engineering" , by: Kalogirou

Alibakhsh,

The original question was not about modeling but about the availability of measured data. There are many empirical models out there to transpose the horizontal to tilted irradiance, but their accuracy depends on many factors, and thus needs to be validated against locally measured data. The development of better models depends on the availability of such data, which is probably why the request was done in the first place!

For more info, see https://www.researchgate.net/publication/236314639_Direct_and_indirect_uncertainties_in_the_prediction_of_tilted_irradiance_for_solar_engineering_applications

Article Direct and indirect uncertainties in the prediction of tilte...

Hello everyone,

I once again want to thank you all for your particirpations and your interests that you give on this subject.

Effectively, as he said Mr.Chris, is the data that has been the biggest problem in the beginning. My programs that have developped can not have value if I can not do this study of "prediction" by these programs, and compare it with the measurements.

For my part, I'm almost finished my study, and I finalize the drafting of a paper. I'll keep you posted in the coming days of my last results.

Cordially.

Dear Ahmed Bouadballah,

Not sure if you still need these type of data or not. By the way, I have some measurement data in my lab. Details at: http://www.jafarkazemi.com/index.php/solar-energy/weather-station

i have the same problem for the place Baroda india

Is the datas available for baroda india"with solar radiation and wind speed"

Swapnil, I don't know of any measured data at your location. This resource of modeled data may help, though:

http://www.nrel.gov/international/ra_india.html

Hello Mr. JafarKazemi,

Thank you so much for the proposal. However I almost finished my programs (and my paper) with available database on the net (NREL). I may be contacting you in the future for a possible cooperation, because my goal is to arrive after at the optimal design of hybrid systems.

Again thank you very much.

Hello everyone,

Until I finish the corrections (by my supervisors) of my paper on the modeling of solar radiation, I want to share with you my results (attached file Jont).

What do you think about these results?

cordially

Ahmed

Also

The resolution of these pictures is too low to understand anything...

An old Chinese proverb says: RMSE and MBE say more than a thousand pictures. ;-)

Data from BMS weather station. This attached file is for the case of 40° tilt angle oriented South.

I totally agree with you Jethro about RMSE and MBE, and also : RRMSE, MABE, MPE, MAPE, R^2... The final result will be in the paper.