Quote:
Panels are rated in Watts of output. This wattage rating is derived by multiplying the panels peak power voltage times its peak power amperage (Watts = Volts x Amps). These ratings are based on standard test conditions (STC) of 1000 watts/square meter of light input, a cell temperature (not air temperature!) of 25 Degrees C (77 Degrees F), and an air mass of 1.5 (slightly above sea level).These standard test conditions are rarely found in "real world" operating conditions. For example:
1000 watts/square meter of sunlight would only be reached around solar noon, with the panel squarely facing the sun, just after a rain shower has washed all the dust out of the air. [Emphasis mine] "Real world" input is usually around 800 to 850 watts/square meter on a bright day (when you factor in dust and air pollution and consider that the panels are laid flat on the roof and are therefore not square to the sun).
When you consider that solar cells are dark blue to almost black, they soak up sunshine and get quite hot so they are operating at temperatures considerably higher than 25' C (77' F). This increased cell temperature translates into a voltage drop and therefore less output.
The air mass changes as you move from sea level to mountaintop. The atmosphere is thicker at sea level so more sunlight is interrupted by dust and pollution and less gets transformed into solar electricity. Conversely, the same panel operating from a mountaintop will see more intense sunlight and will produce more power.
This is not to imply that panel manufacturers are purposely trying to deceive you. It is because "real world" operating conditions are so variable that they had to come up with some standard test conditions so that all panel ratings "
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And some people were wondering why we were scoffing at daily outputs that seemed to require perfect output from the SolarStik panels. I've seen how hot the solar panels can get, and mine run relatively cool, since they have a huge airspace beneath them and around them.
Add in the atmospheric dust, air pollution, imperfections in aiming them... and it isn't any wonder why anyone should doubt any results claiming to get more than 100W output from 100 W solar panels.
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Sailingdog
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Telstar 28
New England
You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.
—Cpt. Mal Reynolds, Serenity (edited)
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