At first glance there's nothing strange about this picture, but if you know the place, you'll soon notice one strange thing - panels are pointing to the north.
The photo was taken from the east, meaning cardinal directions are as follows:
Logically panels should be tilted to the opposite direction, like on this picture from March this year:
Well, our panels do usually face south, but we noticed that in summer, there are certain times of the day when panels capture most sun when tilted to the north. Those time frames are early morning and late afternoon. We noticed that power generation output can improve by 1-2 kilowatts when panels face the north in the right time of the day.
How to explain it?
The explanation is simple: Position of the sun at sunrise/sunset changes in summer and in winter. Everyone knows that sun rises in the east and sets in the west. What most people don't notice is that usually it's not due east (exactly 90 degrees on compass) or due west (exactly 270 degrees on compass) - It's just roughly the east and roughly the west.
It seems that the sun rises due east and sets due west only twice a year (on spring equinox and autumn equinox). On all other days, sun rises somewhat north or south of due east and sets somewhat north or south of due west.
So, when is it north-east and when south-east? When is it north-west and when south-west?
The answer here in Tsukuba, Japan (latitude: about 36 degrees on northern hemisphere), is as follows:
winter sunrise: south-east
winter sunset: south-west
summer sunrise: north-east
summer sunset: north-west
This is not a life saving knowledge but it's a fun fact to know! Moreover, now that we're raising chickens under the panels, I go to the power plant early mornings and late afternoons almost everyday. If I'm there anyway, why not change the tilt and improve performance for a few kilowatt hours a day.
Related article: Power generation - performance report (April 24, 2015).
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