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Solar sales: tracking the Sun

Placing photovoltaic panels perpendicularly to the sun by solar trackers add efficiency to the system, reducing its size and cost per kWh.

Wondering if solar trackers performance actually compensates its cost?

Both dual-axis as well as single-axis trackers have many advantages. Basically, they improve energy output thanks energy losses reduction and reduce potential power losses like those occurring in situations when the incident light is not perpendicular to solar panels. In two-axis trackers angular losses practically do not apply.

What’s more the movement of solar panels reduces deposition of dust and dirt and these two can cause the decrease of the current and voltage as well as to lead to hot spots and mismatch losses.

There are less temperature losses too. Depending on technology, the temperature power loss in PV panels can reach even 4% per 10℃ increase. This will depend also on ambient temperature, wind speed and nominal operating cell temperature as well as the possible back ventilation/panels position. Solar trackers provide natural ventilation.

Less performance losses – this is another advantage of solar trackers that help to operate in optimum power in high values yield.

How much energy can be gained?

The gain of energy will depend on:

  • tracker type

Single-axis trackers give less energy output than dual-axis but are more cost-effective for large commercial power installations while dual-axis trackers are more cost-effective for residential plants, especially if they are combined with high FIT-program.

  • the climate

Solar trackers work better when the sky clarity index is high and there is a lot of direct sunlight. Low sky clarity index will mean that a lot of sunrays is absorbed by pollution and clouds.

  • latitude

Inclining panels in stationary systems will increase the output by 15% when compared to flat position. Trackers however can increase the output by 20-40% depending on the solar radiation level and season of the year.

Trackers adapt not only to daily sun passage but also the changing season. The energy output gain from trackers will be much greater in long summer days (and will include afternoon utility’s peak hours) rather than in winter.

As far as irradiation level is concerned, higher insolation means greater difference between outputs from stationary and tracking systems. For example in Seville, Spain the annual output difference between stationary and tracking systems will be equal to 483 MWh, while in Munich, Germany – 141 MWh. However, in some places in Germany this difference means 40% more output.

Is it practical?

Trackers need to work continuously to be cost-effective. On contrary to stationary racks, they have moving parts that could lead to reduced reliability. However, the motor has to run only few minutes a day and electronic system is pretty simple. Dual-axis systems are considered to have slightly lower reliability due to their higher complexity but having a look at home appliances- it’s difficult to find ones that are not equipped with motors.

The most critical step when installing trackers is to install properly the sensors (in case of dual axis- one is tracking azimuth from East to West, another controls the height of the sun). Another thing is to verify whether panels are placed perpendicularly to sunrays, because even small deviation can decrease the energy output by few percent. Later on, the automatic adjustment of panel position will take 3-4 minutes looking for brightest point in the sky.

How about costs?

The cost of energy produced by photovoltaics can be reduced even four times thanks to trackers. It should be noticed that thanks to tracker we can reduce the modules array which also means applying smaller, less expensive inverters and other components.

Trackers are quite a trade-off between the cost of land (since they require more space than traditional construction, especially dual-axis ones) and price of energy you get. Nevertheless, for large projects the cost of land can be an irrelevant drawback.

When it comes to capex, the tracker price is approximately equal to 0,75-1,25 $/Wp. Operation and maintenance costs for 1-axis tracking can be as much as 0,01 $/Wp more than traditional fixed-tilt systems. Tracking systems also consume energy, it is however only 10% of the energy produced annually.

Now you can present pros and cons of solar trackers. Are those system viable in your region? To compare different scenarios of energy production, try EasySolar app – this will also help you to create the best offers for your customers. Do you want to find our more how to sell solar? Click here!