### How do I compare the yield of photovoltaic and space cooling

The company SkyCool from America promises higher yields than photovoltaics (1000kWh/m²), is that really possible?

In the 19th century, a British-German astronomer named William Herschel told the world about infrared radiation. Then a few other people like Josef Stefan and Ludwig Boltzmann found that the energy exchange between two surfaces has a constant that found its way into a now famous law called the Stefan-Boltzmann equation. One form of this formula can be used to calculate the net exchange of radiant heat (Qrad, Watts) between, for example, the roof of a building and the sky. The formula is: Qrad = εσA(∆T4)
where
ε = surface emissivity of the roof
A = roof area in m²
σ = the Stefan-Boltzmann constant(5.6704 × 10 -8 W / m² ∙ K4)
ΔT = temperature difference between space and the roof in K [Kelvin = ( TºC + 273.15)]

With this formula you can calculate the possible savings in watts. I have published a simple online calculator on my blog . As is so often the case, the happy medium could be the solution, since these cooling modules work 24 hours a day, this technology can be combined very well with photovoltaics and is therefore definitely something for data centers and cold stores.

 Fläche: m² Temperatur: C°(Grad Celcius) Emissivität(0-1) ε(Punkt für Komma) Watt oder Qrad: Watt/