The Different Types of Solar Simulators – Flashed vs. Pulsed vs. Steady-State
Solar simulators can be divided into two general categories: steady-state or continuous and flashed.
Continuous or Steady State Solar Simulators
A steady-state solar simulator has a light source that is continuous over time. Most of the specifications from the standards directly apply to this type of solar simulator. Steady-state solar simulators tend to be used for smaller areas and are most commonly used in low-intensity testing. They can usually generate between 1 sun (1 sun=1000 W/m2) and several suns. Steady-state solar simulators can have several different types of lamps to extend the spectrum in the far IR (>1200 nm).
Applications of Steady State Solar Simulators
It is common to see steady-state solar simulators in lab-based settings in commercial and academic labs. The labs can range from testing and researching solar cells to materials testing and photochemistry. These are just a few of the common areas. Check out our solar simulator applications page for a list of additional applications. What matters to experts in these areas is that the light is stable over time, accurate to the spectrum, and uniform across the sample. The metrics listed will be examined in the next chapter’s classification section.
Pulsed and Flashed Solar Simulators
Unlike the steady state, pulsed and flashed solar simulators do not have a continuous light source over time. This type of solar simulator was invented to prevent heat buildup in the tested device generated by a lamp light source. Not having continuous illumination can be achieved by either having a light source turned on and off (flash solar simulators) or by using a shutter to block the light.
Flashed Solar Simulators
The first method involves a flash of illumination that lasts several milliseconds. Using this method, each flash may generate very high intensities of up to several suns. The main issue that sometimes arises from this simulator is that it is technically challenging to obtain reproducible intensities and spectra from one flash to the other.
Because the light source is not continuously on, temporal stability does not apply directly to this simulator, but we can measure reproducibility by comparing one flash to another.
Pulsed Solar Simulators
Alternatively, a shutter can quickly block or unblock the light from a continuous source instead of turning the light on and off. Typically, these pulses range from 100 milliseconds (ms) to up to 800 ms for special Xenon long pulse Systems.
Applications of Flashed or Pulsed Solar Simulators
With the advent of LED solar simulators over gas discharge solar simulators, discussed in prior chapters, heat dissipation isn’t as significant of a concern with LEDs. However, there are still industries that do require flash. Photovoltaic lines, a.k.a. solar panel manufacturing, currently flash test. Outside of the Photovoltaics field, there are some applications where flashed, pulsed, or “chopped” light comes into play, such as:
- Photochromatic glass- A sensible use is to have a shield turn black to block out a welding flash. What better way to see how fast the shield darkens than with a flash?
- Photochemistry—A few applications require a non-steady-state light source to start a reaction quickly. Examples of these would be solar water splitting and artificial photosynthesis.
- Photobiology—Much like photochemistry, researchers study photosynthetic efficiency or photobiological processes. An example would be how algae behave when not typically exposed to long-duration light.
The list could go on for applications that typically used flashed and pulsed light as the primary light source; however, what ties them together is the need for a quick burst of light once or on a cycle. When it comes to your research, a good rule of thumb question to ask is:
Does my work require long-duration and stable light, or does it require a quick pulse of light?
This concludes our chapter on Flashed, Pulsed, and Steady-State solar simulators. For more technical information on our steady-state solar simulators, visit our LED solar simulators product page.
Our next chapter will examine the ASTM, IEC, and JIS standards, with a heavy emphasis on the IEC 60904-9:2020 standards that classify a solar simulator’s quality. See you there!
