Solar spectra datasets at optimum and vertical installation angles in central Europe (Berlin) during 2020, 2021 and 2022

This article provides datasets containing three years worth of solar spectra for the optimum installation angle of 35° and the building-integrated-photovoltaics relevant vertical angle of 90°. These datasets were obtained by measuring the spectrally resolved solar spectra using a five minute interval, where two sets of spectrometers, which measure different ranges of the solar spectrum, were employed. In addition, a merged dataset of these two spectral measurements, related to every specific five minute interval measurement, is provided. An analysis and interpretation of the data using only year the 2020 is provided in “Measurement and analysis of annual solar spectra at different installation angles in central Europe” [1].


Specifications
Radiation Specific subject area Spectrally resolved solar radiation on a tilted surface Type of data Table  How the data were acquired Two sets of spectrometer sensors from "eko-instruments" (MS-711 and MS-712) were installed in PVcomB/Helmholtz Zentrum Berlin (52 °25 52.5 N 13 °31 25.7 E) at two different angles of 35 °and 90 °. The spectrometer sensors provide a spectrally resolved measurement of the incident solar spectrum, each providing different ranges. The MS-711 has a measurement range of 30 0-110 0 nm and the MS-712 has a measurement range of 90 0-170 0 nm. The sensors have an optical resolution (FWHM) better than 7 nm with a wavelength accuracy of ±0.2 nm. The MS-711 has a temperature dependency below ±2% within an operating temperature of −10 to 50 °C, whereas the MS-712 has a temperature dependency of ±5% within a working temperature of −10 °C and 40 °C. The temperature is controlled at 25 °C ( ±2 °C) within an ambient temperature range from −10 °C to about 40 °C and between 25 °C and 32 °C above an ambient temperature of 40 °C and below 50 °C. Each measurement is controlled automatically, with an exposure time from 10 ms to 50 0 0 milliseconds and a field of view of 180 °.

Value of the Data
• The solar spectral data for two different angles have not been reported up to now.
• After integration of each solar spectrum, the data can be used as an input for calculations regarding yearly PV energy yield [3] . For this, PV characteristics such as spectra response and photovoltaic efficiency are needed. • The data can be used to compare spectrally resolved irradiances at two different angles.
• Research institutes, universities, companies and private users in the field of photovoltaics can benefit from these data. • The data can be evaluated for specific use cases by applying photon energy-material relations (e.g. Solar cell spectral response) [4] .

Objective
The objective of the data is to provide insights regarding solar spectral differences between the optimum angle of 35 °, at which most installations at the presented location are installed, and the building integrated photovoltaics (BIPV), as these installations are often found in a vertical orientation. Fig. 1 shows a picture of the outdoor facilities, where the two spectrometers at an optimum tilt angle of 35 °degrees and two at 90 °(all facing south) can be seen. For the 35 °i nstallation angle, the two spectrometers are labeled.

Data Description
The datasets provide solar spectra for two installation angles: for an optimum installation angle of 35 °and for a vertical angle of 90, relevant for building-integrated-photovoltaics. The datasets are provided as compressed raw data as measured by the MS-711 (300-1100 nm) spectrometers (S1) and by the MS-712 (90 0-170 0 nm) spectrometers (S2). The merged data measured by MS-711 and 712 (S1 + S2) is also provided. Fig. 2 . Shows a flow chart of the data measurement and collection. Due to the size of the three-year datasets, we divided the whole datasets in three smaller compressed packages (.zip) per angle and per year, where each .zip file contains at least two csv files per year as described in Table 1 .

Experimental Design, Materials and Methods
The data was acquired using pairs of spectrometers installed outdoors on top of a building in Berlin (52 °25 52.5 N 13 °31 25.7 E) on a metallic rack with two different tilt angles (See Fig. 1 ).
The spectrometers were provided by EKO-instruments [2] . The first spectrometer is the model MS-711, which measures spectral irradiance within a range of 30 0-110 0 nm. The second spectrometer is the model MS-712 with a measurement range of 90 0-170 0 nm. The spectrometers have a wavelength accuracy of ±0.2 nm. Both spectrometers have an optical (wavelength) resolution (FWHM) better than 7 nm and both spectrometers possess a field of view of 180 °. For the acquisition of this data the integration time was set to 5 min intervals. The data was merged automatically by software provided by EKO-instruments (i.e. WSDac, WSDisp).

Ethics Statements
All authors comply with the ethical guidelines contained in Data in Brief's Guide for Authors.
The data was obtained without any involvement of human subjects, animals, or social media platforms.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data Availability
Solar spectra datasets at optimum and vertical installation angles in central Europe (Berlin) during 2020, 2021 and 2022 (Original data) (HZB Data Service).