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Table of Contents
Photovoltaic modules
Two photovoltaic modules are installed at IEK-8 at Forschungszentrum Jülich to measure their radiation dependent energy yield by tracking the maximum power point in the recorded I-U-Curve.
Module I: SolarWorld SW 235-poly, polycrystalline
Module II: Solarmodul First solar FS-380, thin-film
Photovoltaic modules installed at JOYCE (front: Module I, back; Module II)
Principle - Photovoltaic
Photovoltaic modules convert radiation into electrical energy based on the so called photovoltaic effect (described by Einstein 1905). The photovoltaic effect is the stimulation of an electron to a higher energy state caused by absorption of light. Photovoltaic modules are based on semiconductors since their valence- and conduction band are completely separated, but the band gap is in the range of the energy of a photon. Thus, the photovoltaic effect causes electrons to migrate from the individual molecule structure to the conduction band. These electrons are so called free electrons. They are able to move randomly inside the crystal structure of the semiconductor. In order to produce electricity, which means to collect the excited electrons on the one side and “holes” on the other side, the semiconductors are p- and n-doped. In case of a silicon based module p-doping means to include atoms of the 3. main group and n-doping to include atoms of the 5. main group. In the region of contact, electrons of the n-doped layer move towards the p-doped layer and induce an electric field (depletion area). After a very short time this electric field reaches an equilibrium state since no more electrons can migrate to the p-doped layer. Now the free electrons are accelerated towards the positive depletion area due to this electric field. Thus, the negative charge is trapped in the conduction band in the n-doped layer and the positive charge is trapped in the p-doped layer. This induces an electric potential difference, which can be tapped from the solar module.
Principle - Yield measurements
The I-V curve (current voltage characteristic) of the modules is measured by a progressive increasing of the consumer resistance and simultaneous I-V measurements. The produced energy is released via a radiator.
Measurement modes
- Measurements with 1 minute temporal resolution (voltages, maximum current, irradiance, modue temperature)
JOYCE-CF Standard Operation Procedures
The instrument performs several scanning patterns and uses the remaining time for vertical staring.
Scan patterns are currently:
- Every 5 minutes doppler beam swinging (DBS) (12×14sec/hour=2min48sec/hour), i.e. one vertical and two tilted beams in eastern and western direction to derive instantaneous local wind profiles
- Directly followed by a 3 beam VAD (VAD-3) (12×14sec/hour=2min48sec/hour), i.e. three tilted beams in at 0, 120 and 240 deg azimuth and 30deg zenith distance to derive instantaneous local wind profiles
- Every 15 minutes a velocity azimuth display scan (VAD-36) (4×124sec/hour=8min16sec), i.e. a conical scan at 75oelevation to derive area averaged wind profiles
- Every 60 minutes a range height indicator (RHI) (1×104sec/hour=1min44sec/hour), i.e. a vertical section from east to west with 5deg elevation steps (37beams)
- The rest of the time is vertical staring, i.e. vertical staring is interrupted every 5 minutes and sums up to 47minutes/hour
Data availability
Most of the following data products are provided via the SAMD database. If you would like to have additional data or recent data that have not been uploaded to SAMD yet, please fill the data request sheet and send it to info@joyce.cloud
Dataset | Temporal resolution | File size | Filename | Retrieval / Remarks |
---|---|---|---|---|
Vertical stare data (Backscatter, Doppler velocity) | 2 seconds | 1 file per day (180 MB) | sups_joy_dlidST00_l1_any_v00_YYYYMMDDHHMMSS.nc | available on SAMD |
3D wind profiles from custom scanning | 5 minutes | 1 file per day (3.3 MB) | sups_joy_dlidCUST00_l2_wind_v00_YYYYMMDDHHMMSS.nc | available on SAMD |
3D wind profiles from Doppler beam swinging | 5 minutes | 1 file per day (3 MB) | sups_joy_dlidDBS00_l2_wind_v00_YYYYMMDDHHMMSS.nc | available on SAMD |
Mixing layer height from vertical velocity | 5 minutes | 1 file per day (180 MB) | sups_joy_dlidST00_l2_zmlaw_v00_YYYYMMDDHHMMSS.nc | available on SAMD |
3D wind profiles from VAD-36 | 15 minutes | 1 file per day (1.6 MB) | wind_vad-36_YYYYMMDD.nc |
Link to current observations
Current observations at quicklook archive
Measurement examples
Click here for more plots and explanations
The figure shows a velocity azimuth display (VAD): vectors give direction and speed of horizontal wind at time and height. Vectors pointing upward indicate south wind, vectors pointing to the right indicate west wind. Color shading gives the backscatter coefficient.
Doppler lidar History
Period | Place | Project |
---|---|---|
12.9.2012 - today | Research Center Jülich, Germany | TR32 |
26.7.2012 - 31.8.2012 | Engelsdorf, Germany | TR32-patvap |
7.11.2011 - 26.7.2012 | Research Center Jülich, Germany | TR32 |
Technical specifications
Parameter | Specification | Remark |
---|---|---|
Wavelength / nm | 1500nm | |
Pulse energy / $\mu$J | ~100 | see ARM Doppler lidar handbook |
Pulse width / ns (m) | 150 (22.5) | see ARM handbook |
Repetition Rates / s | 1/15000 | i.e. 15000 laser pulses per second (=Pulse repetition frequency PRF) |
1.67 | avg.beam i.e. N_avg pulses averaged and processed ⇒ dead time=0.67s | |
300 | Doppler Beam swing (DBS) with 3 beams ([azi,ele] = [0,90],[0,75],[90,75]) | |
900 | Velocity azimuth display (VAD) with 36 beams ([azi,ele] = [i*10,75]) | |
3600 | vertical slice (RHI) with 18 beams ([azi,ele] = [109,i*10]) | |
N_avg | 15000 | number of pulses to be averaged in one 'beam' |
resolution / m | 30 | range resolution (adjustable from 15m onward) |
Field-of-View / deg | 360 x 90 | free alingment of the beam |
maximum range / m | 9000 | adjustable, but restriced to sufficent backscatter (aerosol, cloud droplets or ice crystals) |
velocity resolution / ms-1 | 0.0382 | adjustable |
velocity precsision / ms-1 | < 0.20 | for SNR > -17dB |
max velocity / ms-1 | 19.2 | = Nyquist Velocity (adjustable) |
Aperture / mm (area /m2) | 75 (4.417e-3) | see ARM handbook |
Size / cm³ | 80 x 53 x 40 | |
Average Power consumption / W | 140/250 [600] | (wo/w Heating/cooling) [The power supply shall provide 600W] |
Weight / kg | 110 | with transport case |
Manufacturer | Halo Photonics | |
Year | 2011 | |
Instrument | streamline Instrument #17, XR version in 2010, 15kHz PRF, 10km max range |