Solar panels track the sun for more efficiency

Jan 31, 2011

Photovoltaic modules equipped with a moveable mounting and a new control system from Siemens are able to precisely follow the course of the sun. Thanks to a new algorithm based on astronomical data, the solar panels track the sun in line with not only the time of day but also the time of year and the precise geographical location of the photovoltaic installation. As a result, their energy yield is more than 35 percent higher than fixed systems.

A decisive factor in the of a is the angle of incidence at which sunlight strikes the surface of the module. In the case of fixed panels, sunlight hits the at an oblique angle for most of the day. A maximum yield in terms of energy and therefore is only achieved when sunlight strikes the cells perpendicular to their surface. So the obvious solution is to fit the solar modules to a movable tracking system that precisely follows the course of the sun. The sun’s position depends on not only the time of day but also the time of year and the location of the photovoltaic installation. The Simatic S7-1200 control system from therefore calculates the perfect alignment for the solar modules on the basis of their precise location, anywhere in the world, and the exact time and date.

This calculation is based on the “Simatic Library for Solar Position Algorithm,” which is stored in every control unit. Siemens obtained a license for the very precise from the National Renewable Energy Laboratory (NREL) in the U.S. On this basis, the control system is able to determine the position of the sun to an accuracy of 0.0003° and align the photovoltaic module accordingly. Three-phase AC motors power a dual-axis tracking system: This swivels the module in a semicircle along the azimuthal axis, thus tracking the sun’s daily course from east to west, and tilts the module along the zenithal axis, tracking the height of the according to the time of day and year. In the process, the control system also prevents neighboring modules from overshadowing one another during the morning and evening hours, when shadows are especially long. The software bases its astronomical calculations on parameters such as longitude, latitude, and the exact time.

In addition, the control system can also take weather conditions into account. When faced with high winds, for example, it moves the modules to a position of least resistance, where they can withstand winds of up to 130 kilometers per hour. In a similar manner, the tracking system can be programmed to react to snow, thunderstorms, fog, and darkness.

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Eikka
5 / 5 (1) Jan 31, 2011
A very simple analog circuit with feedback would be able to track the sun automatically by following a bunch of light dependent resistors.

No need to know where the sun will be in a minute, because the robot will automatically point towards the direction where there's more light.

And you only have to control one axis, because the other axis follows a 24 hour cycle anyways.
semmsterr
not rated yet Jan 31, 2011
A very simple analog circuit with feedback would be able to track the sun automatically by following a bunch of light dependent resistors.

No need to know where the sun will be in a minute, because the robot will automatically point towards the direction where there's more light.

And you only have to control one axis, because the other axis follows a 24 hour cycle anyways.

...remember the part about the wind and storms etc.
geokstr
1 / 5 (1) Jan 31, 2011
I wonder if they've calculated whether the electricity required to continuously move the panels during the day and return them to their starting position to be ready for the dawn, vs the added electricity gained from this process, results in a net gain or not? The article doesn't say whether the 35% increase is net or gross.
VOR
1 / 5 (1) Jan 31, 2011
I wonder if they've calculated whether the electricity required to continuously move the panels during the day and return them to their starting position to be ready for the dawn..."

You should've known that a properly balanced and well-designed carriage would use a minimal amount of power. Of course the net gain far outways the useage. The useage would be higher when a certain amount of wind is present, but it depends on how cleverly they design it. For example it might not
hurt the output for it to be able to lock for a while then move, etc, cutting down on the power needed to hold it, especially against a breeze.
or it could just be geared to resist- 'fighting' wind power here lol.
RealScience
5 / 5 (2) Jan 31, 2011
Eikka - the astronomical tracking also allows the system to be ready when the sun breaks out from the clouds.
The other axis also follows a 24-hour cycle only with a 'polar axle' tracker (also called a daily/seasonal tracker). Both axes can be clockwork with this axle (Google 'brant axle nasa' for a great example).

Geokstr - the motors on a two-axis track consume very little power because the system moves slowly. Typically the parasitic loss for the motors is around 0.1%.

VOR - correct for the flat panels shown. CPV (which in general requires trackers) needs to keep tracking the sun to be productive.
geokstr
not rated yet Feb 01, 2011
You should've known that a properly balanced and well-designed carriage would use a minimal amount of power.

I sincerely apologize and abjectly prostrate myself before your almighty knowledge, and should understand humbly that I must aspire to be as brilliant as yourself in all areas of science and engineering so I don't have to waste the oh so valuable time of someone so far above me by asking questions.

VOR - I'm laughing at the "superior intellect".

As a matter of fact, I didn't major in engineering only because I hate trains.

RealScience, I appreciate your civil and informative response to my question which was apparently way to dumb for the likes of some others.