MPPT conrtoller in comparison to a traditional system:
MPPT conrtoller provide in comparison to conventional controller PWM (Pulse With Modulation) to a minimum 15% load power and more.
PWM Load :
By using the traditional charge controller, the solar panel is directly connected to the battery to charge. The battery defines the operating voltage of the module. Therefore, the power of load is still lower than if the controller was directly connected with the module. The rated power of a solar panel is always the result of the product voltage and current to the point of optimal work at 25 °C.
In the framework of a 12V system, the voltage of the battery is located between 10-15V. The conventional solar panels have a maximum voltage of approximately 17V. Therefore, in the voltage range 10-15V, the available power is reduced.
Depending on the charge state of the battery, the conventional systems are not able to use the power available. On average, this represents the loss of approximately 20 %.
The MPPT controller determine of uninterrupted and with a great accuracy the point of optimal work on the output curve on which the voltage and the current UMPP IMPP reach a maximum (Product UMPP * IMPP = PMPP ). The energy resulting from the point of optimal work is electronically converted to battery voltage the more low to charge the battery with the higher current possible.
A module of 100W ( UMPP = 17V) loaded using the controller Tristar- MPPT a battery of 12V. In the ideal case, 5.88A of current flows in the solar controller MPPT (17V * 5.88A = 100W) as the output voltage of only amounts to 12V (battery voltage), the output current will rise to 8.33A (8.33A * 12V = 100W). More than the difference between Umpp and voltage of the battery is great, the more current with which the battery will be charged will increase. More than the state of charge of the battery is low, more than the load current from the battery is high.
Changes in the surrounding environment:
The changes of the surrounding environment (temperature, radiation) lead to a fluctuation in values Umpp . Partial shadows or a change in temperature of the module are causing the greatest differences. While the MPPT is continuously adapted to the respective conditions, the performance remains to a large extent the same. The difference between conventional controller and MPPT tracker is very easy to see when low temperatures. The Umpp value shifts to the top and the power of the module as well as the load current increases in function. A conventional controller would benefit in nothing in the case of low temperature.
Sizing of the MPPT controller modules for:
For optimum operation it is very important that the controller specifications are respected. Thus the voltage to empty during low temperature must not exceed in any case the maximum input voltage permitted by the controller. A no-load voltage too high (Uoc) can damage the electronic components in the controller. For a battery voltage and a MPP voltage of a module, it is essential not to exceed the recommended solar power.
Attention: The load current from the battery is in all cases higher than the current of the module. The specifications for the current maximum MPPT, multiplied by the voltage of the battery decide to the maximum power of the module to use.
A MPPT controller 15A is used with a 12V system (field of battery voltage: 10-15V). The " rating" current multiplied with the voltage of the battery gives about 200W (15A * 13.3V= 200W). The maximum power of the module should not exceed 200W.
A MPPT controller 15A is used with a 24V system (field of battery voltage: 10-15V). The maximum power of the module should not exceed 400W (15A * 26.6" FOR V= 400W).
An overrun of the solar power allowed (within the limits of the currents allowed) does not lead to a damage to the controller. The higher power that the limits calculated in examples 1 and 2 simply cannot be converted and will be lost. The MPPT controllers can be used with all types of modules. By contrast, the PWM controller cannot only be used with modules which are tailored to the batteries.
Optimization of the performance:
The performance of a controller Mppt may vary slightly with the different voltages of battery voltages, modules, and powers.
The use of the MPPT controller has many advantages. The most relevant argument is certainly that it is more difficult to find suitable solar panels to recharge battery. Because of this, it was more and more use of modules for "network injection" which are best markets but which due to their higher voltage cannot be used with a conventional controller. The price difference between a conventional and a controller controller MPPT is nothing compared to the savings that are achievable by purchasing a classic module.
The controller has a optimal behavior when a low solar radiation or when a part is shaded. The MPPT controller allows also to lengthen the life of the battery through its a technique of load.
For standalone installations of 100W and less, a traditional controller is recommended.
The tendency to facilities with powers and higher yields, the future belongs to the controller MPPT
There are significant technical differences between the various controller of the Mppt market:
The ability to load current: 15 to 40A for the entries of the range, until 80A for the more sophisticated products.
The characteristics of input voltage: The Mppt controller entry-level are able to manage in general of parks batteries in 12 or 24V and are often limited to the voltages < 50Voc. The best products accept up to 150 Voc.
Ex:MPPT controller entry-level who worked in 12V battery with an input voltage max from the solar panels of 28Voc ( empty voltage ). For an input voltage more important therefore >28Voc, the controller will be able to work that in battery charge 24V.
A Mppt controller of a brand of notoriety as the Tristar Mppt of among Morningstar or the Fx series among Outback will be capable of managing park batteries from 12 to 48V (60V to Outback ) with a wide input range until 150 Voc.