Solar irradiance curves

A 1995 reconstruction of historical solar output levels from 1600 to 2000 shows that solar irradiance has risen over time, hut with many short-term peaks and troughs in the overall curve of increase, increas-... 

The second parameter is the volume of H2 produced by a standardized 1 kWp PV generator as indicated in Figure 3. The above mentioned linear tendency is also valid in this case, and let us extracting some typical values from the slopes of both curves. This means that 0.25 m3/kWh/m2 and 0.33 m3/kWh/m2 of H2 can be supplied by a standard 1 kWp PV system. On a yearly basis if we consider as an example the corresponding horizontal solar irradiation of wilaya 16 (Algiers) and wilaya 11 (Tamanrasset) we may obtain 640 m3/kWp and 720 m3/kWp, for fixed tilt and two-axis tracking respectively. 

Figure 13. Solar spectral irradiance curve (From reference 33).

The operation of a photovoltaic system is governed by the current-voltage characteristic curves of the photovoltaic module. Such a set of curves, for different values of the incident solar irradiance and constant photovoltaic module temperature, is shown in Figure 2.4. The curves consist of two parts. In the first part the photovoltaic module behaves as a constant-current source, with amplitude proportional to the solar irradiance level. In the rest of the curve, current decays... 

Fig. 4.18 Solar spectral irradiance E outside of the atmosphere. A new solar spectral irradiance curve for the aerospace community data taken from http // rredc.nrel.gov/solar/standards/amO/newamO.html.

Figure 4-5. Wavelength distributions of the sun s photons incident on the earth s atmosphere and its surface. The curve for the solar irradiation on the atmosphere is an idealized one based on Planck s radiation distribution formula (Eq. 4.3a). The spectral distribution and the amount of solar irradiation reaching the earth s surface depend on clouds, other atmospheric conditions, altitude, and the sun s angle in the sky. The pattern indicatedby the lower curve is appropriate at sea level on a clear day with the sun overhead.

Figure 7-2. Wave number and wavelength distributions for direct solar irradiation, skylight, and radiation emitted by a leaf at 25°C. Wave number (introduced in Problem 4.2) equals the reciprocal of wavelength and thus is proportional to energy (see Eq. 4.2a Ex = hv = hc/Xvac). The areas under the curves indicate the total energy radiated 5direct is 840 W m-2, iSsky is 80 W m-2, and the IR emitted is 860 W m-2.

Figure 21. Typical spectral response curve of the incident photon-to-current conversion efficiency (IPCE) for a mesoporous Ti02 electrode sensitized by N3 and the black dye . A normalized solar irradiance spectrum under AM 1.5 conditions is superimposed for direct comparison.

Figure 13 Spectral irradiance. Curve I Exiralerresirial solar radiation. Curve 2 Terrestrial radiation of a black body of temperature 300K = 27 C.

Some authors suggest the criterion of no overshadowing between 9 a.m. and 3 p.m. (i.e., 3 hr on either side of solar noon). Others are more demanding, suggesting 4 hr before and after solar noon (i.e., 8 a.m. to 4 p.m.) yet others are more permissive, with limits of 10 a.m. and 2 p.m. (i.e., 2 hr). All of these limits would apply to the mid-winter day. Figure 21 shows a typical irradiance curve for a northfacing collector (located in the Southern Hemisphere) with a 9 a.m. and 3 p.m. cut-off (other periods are shown by dashed lines). It is obvious that most of the radiation is received around solar noon, and the fraction lost (outside these time limits) is not excessive. 

Fig. 3.7 Examples of spectral irradiance curves for a commercial solar simulator (Newport Oriel). The curves are normalized to the AM1.5G and AM1.5D spectra top and bottom graphs, respectively) by matching the total power density between 250 and 1,100 nm...

FIGURE 2 Extraterrestrial solar irradiance, measured by a spectrometer onboard an Earth-orbiting satellite. The UV spectrum (119 < 1 < 420 nm) was measured by the SOLSTICE instrument on the UARS satellite (modified from a diagram provided by G. J. Rottmann, private comm. 1995). The vertical lines divide the various spectral subranges defined in Table I. The smooth curves are calculated blackbody spectra for a number of emission temperatures. 

Figure 4.3.30. Typical steady-state photocurrent voltage curve. The thin Une is the current in the dark, which shows diode behavior. The thick line is the current under standard AM 1.5 solar irradiation.

Fig. 7.2 Illustration of the spectroelectrochemical characterisation of a laboratory scale DSSC with a nanocrystalline Ti02 film sensitised with the RuN3 dye, measured under simulated AM 1.5G solar irradiation (100 mW cm ) electrolyte composition methoxyproprionitrile with 0.6 M propylmethylimidazolium iodide, 0.1 M Lil, 0.1 M tert butylpyridine, and 0.1 M iodine or guanidium thiocyanate 5 pm thick Ti02 film (9 nm particles) and scattering layer, a J-V curve, b IPCE spectrum (Courtesy of Patricia Jesus, Coimbra Chemistry Centre). In an optimised RuN3 DSSC the /sc reaches a value 20 mV and the maximum incident photon to current efficiency reaches 85 % [25]...

But, during the day, the solar irradiation from the sun is not at a constant wattage of 1000 W/m. It varies from a minimum to a maximum. The solar irradiation or the flux for any given day is like a positive sine curve. For the Simulink model, the flux is the input and the output is the power produced by an array. Just changing the number of cells or modules that are connected in series or parallel can alter this power. 

Despite the potential impact of novel photosynthetic routes based on these developments, the most ambitious application remains in the conversion of solar energy into electricity. Dvorak et al. showed that photocurrent as well as photopotential response can be developed across liquid-liquid junctions during photoinduced ET reactions [157,158]. The first analysis of the output power of a porphyrin-sensitized water-DCE interface has been recently reported [87]. Characteristic photocurrent-photovoltage curves for this junction connected in series to an external load are displayed in Fig. 22. It should be mentioned that negligible photoresponses are observed when only the platinum counterelectrodes are illuminated. Considering irradiation AM 1, solar energy conversions from 0.01 to 0.1% have been estimated, with fill factors around 0.4. The low conversion... 

The most direct way to carry out the measurements is in places where the measured solar spectrum is found to be nearly identical to the standard AM1.5G spectrum. By measuring the temperature dependence and irradi-ance dependence of the I/V curve parameters, cell properties may be adjusted to the SRC. Since in most places around the world these SRC conditions cannot be met, characterisation laboratories have been set up with suitable apparatus and procedures to do accurate indoor efficiency measurements under SRC according to international standard norms (ASTM, IEC). This involves... 

Fig. 5.46. Typical I/V curves for an as-produced polymer-fullerene solar cell before and after sealing. Measurements were performed with a solar simulator (Steuer-nagel Solar Constant 575) at an irradiance level of 800 W/m2 and a cell temperature of 55°C. Measured data were corrected to the plotted AM 1.5 values using a calculated mismatch factor of 0.76...

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