How Bright is the Sun in Newport Right Now?
Martek’s solar radiation gauge answers that question 24/7, so if you don’t live in Newport and prefer sunny weather you can check here to see if the sun is shining brightly before driving over (or conversely, if you like dark cloudy days, you can watch for them!).
The total amount of solar radiation reaching earth here is measured 1/2-mile east of the Agate Beach shoreline using a silicon photodiode sensor that has wide spectral-response (it responds almost equally to infrared, visible and ultraviolet light energy). That sensor looks straight-up with a field of view that is wide enough to see almost the entire sky and it therefore sums both direct and diffuse components of solar irradiance (the solar energy coming directly from the sun and that which is irradiated from clouds and everything else in the sky). The sensor produces an electric current with an intensity that is analogous to the total amount of solar energy being received. That current is converted to an analog voltage and the voltage level is digitized by an electronic analog-to-digital converter. The digital values are sampled by remote firmware every 50-seconds and are then sent to a Martek internet server via a UHF radio communications link. Software running on the server generates the analog and digital solar radiation gauge image above in real-time as measured values change.
The solar radiation gauge is calibrated in electrical watts-per-square-meter, so, for example, an indicated value of 500 would mean that at the existing sun brightness, a one-meter-square (3.14 x 3.14 foot) solar panel would generate 500-watts of electrical power if the solar panel was 100% efficient. Unfortunately, solar panels are not nearly that efficient. The single-junction cells used in most solar panels have a theoretical maximum efficiency of 33.16%, but practical problems, such as arranging electrical conductors so they don’t block some of the light, cause the efficiencies of practical single-junction-cells to be less than that. The most efficient solar panels currently available to consumers are 22.5% efficient, but the majority being sold are only 14% to 16% efficient. Consequently, a solar radiation indication of 500 watts-per-square-meter means that a real one-meter-square solar panel would generate somewhere between 14% of 500 watts (70 watts) and 22.5% of 500 watts (112.5 watts), depending on the solar panel’s efficiency.
The UV Index Gauge
A second Martek wide-angle-sky-view solar-sensor is also located 1/2 mile east of Agate Beach which measures only the ultraviolet component of solar radiation reaching earth. That is important, because ultraviolet energy damages skin and eyes. It makes skin age more quickly and can cause skin cancer. It also can damage the natural lenses in eyes and cause cataracts (clouding of natural eye lenses). Additionally, it can cause incurable macular degeneration that is a leading cause of vision-loss in the elderly.
The UV Index Gauge above shows the current risk of ultraviolet skin and eye damage when not near a water surface that can reflect additional amounts of ultraviolet energy. Ultraviolet-filtering sunglasses showed be worn and sunscreen protection should be used outdoors whenever the UV Risk Index displayed by that gauge is moderate or high, or even when the risk-index is low, when near a large water surface that can reflect significant additional amounts of solar energy.
Note that the gauge indications above do not always track up and down perfectly with each other, because they show measured levels of different wavelength-spectrums of energy. During early-morning and late-evening hours a higher-percentage of the sun’s ultraviolet energy is filtered-out during the longer path that light travels through the atmosphere before reaching earth, compared to noontime, when the sun shines straight down through less atmosphere. Clouds and various kinds of air pollution also attenuate different wavelengths of light differently. Because of factors like these, the intensity of light in the visible energy spectrum that we see with our eyes is not a reliable indication of the current level of invisible ultraviolet energy risk. So, if you don’t have a way to check the UV Index on the gauge above, the prudent default is to use both skin and eye protection outdoors during daytime.