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Given the theoretical maximum of daytime duration for a given location, there is also a practical consideration at which point the amount of daylight is sufficient to be treated as a "sunshine hour". "Bright" sunshine hours represent the total hours when the sunlight is stronger than a specified threshold, as opposed to just "visible" hours.
It is a general indicator of cloudiness of a location, and thus differs from insolation, which measures the total energy delivered by sunlight over a given period. Sunshine duration is usually expressed in hours per year, or in (average) hours per day.
In fact, under clear skies a solar panel placed horizontally at the north or south pole at midsummer receives more sunlight over 24 hours (cosine of angle of incidence equal to sin(23.5°) or about 0.40) than a horizontal panel at the equator at the equinox (average cosine equal to 1/ π or about 0.32).
A plot of hours of daylight as a function of the date for changing latitudes. This plot was created using the simple sunrise equation, approximating the sun as a single point and does not take into account effects caused by the atmosphere or the diameter of the Sun.
Sunshine hours for selected cities in Europe Country City Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year Ref. Albania: Tirana: 124 125 165 191 263 298 354 327 264 218 127 88 2,544 [1] Albania: Vlorë: 133 148 173 225 273 318 369 344 279 211 117 99 2,690 [2] [3] Albania: Durrës: 133 135 173 207 279 318 375 325 261 217 147 124 2,696 ...
For example, with an axial tilt is 23°, and at a latitude of 45°, then the summer's peak sun angle is 68° (giving sin(68°) = 93% insolation at the surface), while winter's least sun angle is 22° (giving sin(22°) = 37% insolation at the surface). Thus, the greater the axial tilt, the stronger the seasons' variations at a given latitude.
At the time of the summer or winter solstices, the Sun is 23.44° degrees above or below the horizon, respectively, irrespective of time of day. Whilst the Sun is up (during summer months) it will circle around the whole sky (clockwise from the North Pole and counter-clockwise from the South Pole), appearing to stay at the same angle from the ...
"Total Watt-Hours per Day" = "Total Watt-hours per day needed by appliances" Multiplied by "1.3 times" (the energy lost in the system). Now, to calculate "size of PV cells" OR "number of PV cells" just divide the above obtained "Total Watt-Peak Rating" by "Watt-Peak of each cell OR Watt-Peak of each square meter size", whichever is convenient.