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Positioning Solar panels.

The direction and angle that your panel faces can have a big impact on it's performance by affecting the amount of light that hits the panel each day through the year. Some solar panels move continiously to track the sun but most will not go to the expense and difficulty of implimenting that. If your one of the majority, that are going to fix your panels in one place, then you have to get it right first go.

To get it right we have to make sure that the panels get hit by the maximum amount of light. This happens when the sun is directly above the panel.

Panel Exposure at different angles.

As you can see from above, the angle that the sun hits a panel changes the ammount of exposure. At 30 degrees from the panel, the panel is only exposed to 50% of the light of the sun, at 60 degrees, 87% and at 90 degrees, 100%. This happens because the sun emits the same number of photons in a square cm, but once we put our panels on an angle, those photons are spread across a larger area.

As we all know, at different times of the day the sun moves through the sky and so any stationary panels get exposed to differnet angles, so what is directly above at one time of the day will not be at the next. What you might not know through is when the sun it at it's highest it is not nessisarly straight up, but may be off by an angle. And that angle is different at different times of the year and different at different latitudes. This angle is to the south in the northern hemisphere and the north in the southern hemisphere.
Sum Paths

So we need to take all of this into account. Luckily what is good for your neighbour (aka your rough latitude), is good for you too. So below is a table that will show you what angles to hav your panels on, at different latitudes, at different times of the year.

Latitude Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Example
90N - - 00S 12S 20S 23S 20S 12S 00S - - - North Pole
80N - - 10S 22S 30S 33S 30S 22S 10S - - -
70N 00S 09S 20S 32S 40S 43S 40S 32S 20S 09S 00S - Hammerfet, Norway
60N 10S 19S 30S 42S 50S 53S 50S 42S 30S 18S 10S 07S Oslo, Norway
50N 20S 29S 40S 52S 60S 63S 60S 52S 40S 28S 20S 17S London, England
40N 30S 39S 50S 62S 70S 73S 70S 62S 50S 38S 30S 27S Beijing, China
30N 40S 49S 60S 72S 80S 83S 80S 72S 60S 48S 40S 37S Austin, USA
20N 50S 59S 70S 82S 90 87N 90 82S 70S 58S 50S 47S Veracruz, Mexico
10N 60S 69S 80S 88S 80N 77N 80N 88S 80S 68S 60S 57S Bangkok, Thailand
0 70S 79S 90 78N 70N 67N 70N 78N 90 78S 70S 67S Kuala Lumpur, Malaysia
10S 80S 89S 80N 68N 60N 57N 60N 68N 80N 88S 80S 77S Salvador, Brazil
20S 90 81N 70N 58N 50N 47N 50N 58N 70N 82N 90 87S Iquique, Chile
30S 80N 71N 60N 48N 40N 37N 40N 48N 60N 72N 80N 83N Sydney, Australia
40S 70N 61N 50N 38N 30N 27N 30N 38N 50N 62N 70N 73N Wellington, New Zealand
50S 60N 51N 40N 28N 20N 17N 20N 28N 40N 52N 60N 63N
60S 50N 41N 30N 18N 10N 07N 10N 18N 30N 42N 50N 53N
70S 40N 31N 20N 08N 00N - 00N 08N 20N 32N 40N 43N
80S 30N 21N 10N - - - - - 10N 22N 30N 33N
90N 20N 11N 00N - - - - - 00N 12N 20N 23N South Pole

angles explained.

The angles expressed in the table above are represented by A in the diagram, and the direction to the South or North, eg 90 degrees is perpendicular to the ground. So for example, in Sydney at 40 degrees latitue, we have the angle to put the panel on each month. If we wanted to set it in place for the whole year we might want to average these figures to put your pannel facing north at an angle of 60 degrees.

There are also a few different easy things we can do to improve the exposure of our panels. While constant tracking is complicated, it is easy to move your panels once or twice a year. We can adjust the angle of our panels to have two settings and in summer or winter adjust the angle to get the best of the availible light. So, if we look at our sydney example from before, we can break the year into two and take two averages. That way, in Sydney, we can have our panels at 75 degrees, North facing in the warmer months and 45 degrees in the colder months. And, that should be all you need to know!

If your not sure what you latitude is or you would like to work it out yourself, here is a good method for you.
Measure Yourself
You will need two pieces of paper, some sticky tape and a pen. First cut out a strip 10cm long and 2 cm thick and fold it in half. Sticky tape this to one side of the paper in roughly the spot of the black stick on the above picture. Now all you have to do is put this out in the sun and every hour or two place a mark where the shadow reaches. Connect these dots into a smooth curved line. Fine the shortest place from the line to the center stick and measure the distance, lets call this distance X. Now the best angle for that time of the year is given by inverse sin of 10/X. Pop it into your calculator and set your panel at that angle. and it should be good for that time of the year every year.

After all this, you should now be getting the most from your panels!


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