It's true that our planet is blessed with many free energy sources such as wind energy, hydro energy, sun or solar energy etc but unless these are harnessed and captured optimally the resources could simply get wasted.
Considering this fact, two major systems were developed in the form of MPPT circuits, and mechanical solar trackers for harnessing solar energy most effectively and wisely.
However a layman in the field always tends to get confused regarding the difference between these two systems and sometimes get ill-informed through many myths and incorrect data.
This post is specially written for clarifying the many pros and cons of these two prominent solar harnessing machines, namely the MPPT and the Solar Tracker.
Let's learn which gadget wins the race quality and efficiency wise through the following discussion:
MPPT vs Solar tracker
MPPT is the acronym for Maximum Power Point Tracker, as the name suggests this device is designed to extract maximum feasible VxI or wattage from the panel and deliver it to the load.
An MPPT will basically try to execute two main actions while in use: Firstly, it will track the solar panel maximum available power (V x I) and try to deliver the most of it across the output or the connected load.
Secondly, it will monitor that the load does not attempt to hog the panel by extracting illegitimate or unfeasible amount of watts either due to a short circuit or shunting of the output leads of the MPPT.
If such a condition is detected the MPPT's "shut down" feature instantly triggers in order to correct this unusual or incorrect load situation.
How an MPPT functions
Suppose we have a solar panel with the following specs attached with an MPPT for charging a 12V battery:
wattage: 24 x 2.5 = 60 watts at optimum sunshine conditions.
Optimum or peak sunshine refers to a period during the day when the
sun rays are almost perpendicular to the surface of the solar panel, as
this condition is compromized with the sun's changing position the
output from the panel also suffers and is reduced proportionately.
During optimum sunshine, the MPPT will try to deliver, and charge the battery with 12V @ 60/12 = 5 amps.
You can see that here the current to the battery is boosted and has been doubled in order to keep the net input to output wattage ratio constant and efficient.
Thus the system ensures that the battery which even though has a much
lower voltage specs than the panel continues to get optimum power
from the panel, that is at the rate of 12 x 5 amps = 60 watts.
This is the most interesting and valuable feature of MPPT chargers compared to other forms of ordinary chargers.
However when sun light begins diminishing as the day proceeds to dusk, the panel wattage also begins to deteriorate proportionately, so what does the MPPT do now? Does it continue to offer the same amount of power that it was delivering during the peak sunshine?
The answer is no, the MPPT simply keeps tracking the maximum available power from the panel and reproduces the same at its output load, meaning if the panel voltage and wattage reduces to say, 20V @30 watts, then the 12V battery only succeeds in getting 12V at 30/12 = 1.5amps charging rate.
Although the MPpT is still trying to keep the input/output ratio to unity by rendering the same amount power to the battery that's being provided by the panel, but it's unable to restore sun ray's angle of incidence.
This is one big disadvantage with MPPT trackers, whose power producing ability is restricted to the angle of sun rays on the panel, and it becomes "helpless" as sun begins receding.
Thus an MPPT will not be able to take the advantage of the sunlight throughout the day. So if we analyze the efficiency of the MPPT with respect to the sun's actual delivering power, we may find it to be around just 50% or even less.
The positive aspects of MPPT circuits are: These are compact, solid state, more efficient than other forms of chargers and does not employ bulky mechanical assemblies for the implementations, however the huge downside is that these are unable to track the rays of the sun and therefore fail to take the full advantage of the sun's vast energy output.
How Solar Trackers Functions
Solar trackers are electro-mechanaical systems designed to track the sun rays practically, meaning the solar panel will keep changing it's surface orientation in response to the sun's shifting positions such that it maintains a perpendicular angle with the sun rays throughout the day.
The above movement is executed using motors and an LDR sensor circuit. The LDR sensor circuit constantly monitors the incidence of sun rays and commands the motor to turn the panel accordingly such that the panel keeps tilting from east to west fraction by fraction. A solar tracker also has the ability to analyze an overcast condition and adjust the panel for obtaining the most advantageous or optimal angle of the sun rays.
This ability of a solar panel makes it hugely advantageous compared to an MPPT since it is able to harness and gather almost 95% of the available solar energy at any instant throughout the day.
Although a solar panel becomes attributed with the above feature, it won't possess the ability to convert a dropped voltage at the output into a proportionately boosted current as we studied in the above discussion using an MPPT device.
Therefore if a 24V solar tracker system is directly connected with a 12V battery, although the panel would keep tracking the sun and generate optimum power throughout the day, the battery will not be favored with a doubled current, meaning with the above discussed specs the solar panel which has the ability to produce 2.5V amps at 24V will continue to provide 2.5 amps to the battery contrary to the the boosted 5 amps as produced by the MPPT.
Here the MPPT proves its metal since its above ability becomes imperative and significant and cannot be ignored.
Therefore it shows that an MPPT cannot be ignored even if a solar tracker is being used, and it should be additionally used with a solar tracker in order to make the combination deadly potent and almost 100% efficient under all circumstances.
This combination would ensure that the user is able achieve the maximum from the available solar panel and the sunshine, although this would mean some heavy investments initially, the costs could well be covered within a few seasons of use of the system.
In the end comparing the two counterparts we can contemplate and conclude that the distinct winner is the solar tracker system.
That said, an MPPT also becomes extremely essential for achieving outstanding results from a solar panel system and also when a fixed solar panel is selected by an user.