Thursday, July 18, 2024

The significance of measuring albedo at photo voltaic websites – pv journal Worldwide


With the proliferation of bifacial modules, albedo estimates have develop into extra essential and with builders unwilling to put in climate stations to evaluate the photo voltaic useful resource, a well-liked choice has develop into third-party, on-site measurements for durations as quick as someday. Is this a suitable compromise between costly in situ measurements and fewer correct satellite tv for pc information? Everoze’s Stefan Mau discusses the potential advantages and limitations of this method.

From pv journal 6/24

Although an correct evaluation of photo voltaic assets is vital to make sure the reliability of an power yield evaluation, most research rely solely on satellite tv for pc irradiation information. Solar builders hardly ever dedicate assets to putting in a climate station to acquire ground-measured information previous to building of the PV challenge, primarily as a result of massive prices concerned. concerned. Running a climate station for a 12 months prices between €40,000 ($43,000) and €60,000. A satellite tv for pc dataset prices a number of hundred euros.

The growth of bifacial modules has difficult the analysis of obtainable photo voltaic assets. The arrival of the irradiation on the again aspect of the bifacial modules is normally decided by the albedo, which is the ratio between the downward irradiation reaching the bottom and the upwelling irradiation mirrored by it. Like different information, reminiscent of international or diffuse irradiation, albedo is obtained from satellite tv for pc imagery. The main information suppliers additionally supply this info. Albedo is harder to evaluate than low irradiance, as a result of it’s influenced by the character of the earth. Satellite information decision is, at greatest, about 1 km² and the character of the land, and due to this fact albedo, can fluctuate drastically over a comparatively small space. Albedo additionally varies all through the day, relying on components such because the place of the solar, climate, and time. A small error within the albedo worth can simply trigger a 0.5% impact on a yield estimate that may have an effect on challenge estimates by a big amount of cash.

These components lead us to the conclusion that albedo ought to be measured. However, the price of a one-year marketing campaign continues to be a “no-go” for many builders. On the opposite hand, some service suppliers suggest short-term measurement campaigns the place the albedo is measured on website for one or a number of days. This measurement is then used to calibrate the satellite tv for pc albedo information.

Short time period advantages

Since Everoze is usually requested to make use of information corrected for short-term albedo measurements, we need to make our personal opinion on the advantages of such short-term measurements. We use public, quality-checked climate station measurements, together with international irradiation and albedo numbers, and study the impact of calibrating these information utilizing short-term albedo measurements from a day and 7 day campaigns.

We used information from the Surface Radiation Budget Network (SURFRAD) from seven websites within the United States. The high-resolution information have been taken over six years, from 2017 to 2022, and used to calculate the month-to-month reference albedo for every of these websites, averaged over six years. For instance, the reference albedo for January is the common of all January albedo values ​​from 2017 to 2022. We additionally downloaded satellite tv for pc albedo information from the Prospect instrument of photo voltaic irradiance information firm SolarGIS for seven you places.

Everoze utilized in depth information high quality checks to SURFRAD, which led to the deletion of a small variety of days over a six-year interval. Then we used the albedo of every day as a one-day marketing campaign and the seven-day durations as weekly campaigns, correcting all satellite tv for pc information primarily based on these campaigns. Finally, utilizing the photo voltaic design instrument PVsyst, we simulated a theoretical single-axis monitoring, bifacial PV asset and ran a yield state of affairs displaying the six-year common SURFRAD albedo, uncooked satellite tv for pc albedo, and satellite tv for pc albedo. .

We examine yields. A measurement marketing campaign is taken into account helpful if the distinction between SURFRAD information and the corrected albedo is decrease than the distinction between SURFRAD and the uncooked satellite tv for pc albedo. The determine under illustrates the outcomes for a one-day and seven-day marketing campaign for every of the seven challenge areas.

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Value for cash

The outcomes present that the one-day marketing campaign ought to be rejected as a result of it’s not helpful typically, particularly in the course of the winter. Seven-day campaigns are normally worthwhile in the summertime. The writer notes that information from different areas might result in completely different conclusions. Other components reminiscent of location, peak, calibration, and the frequency of albedometer cleansing should be thought-about with care. Everoze recommends making the funding to cowl a whole 12 months of measurements, slightly than just some days. It could also be costly within the quick time period however will probably be value it over the lifetime of the challenge.

About the writer: Stefan Mau is {an electrical} engineer and has labored in photo voltaic since 1999, together with R&D, testing and certification, measurement, and consulting providers in Spain, Germany, and Austria. Before becoming a member of Everoze, he was a world contact for PV plant operational providers at DNV GL. At Everoze, he helps industrial PV providers reminiscent of due diligence, bankability, and power assessments and coaching. He is a part of the Spanish standardization committee for PV modules and holds a patent.

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