What is MPPT solar charge controller?

Published: 25th January 2010
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1.What is MPPT solar charge controller?

A maximum power point tracker (or MPPT) is a high efficiency DC to DC converter which functions as an optimal electrical load for a photovoltaic (PV) cell, most commonly for a solar panel or array, and converts the power to a voltage or current level which is more suitable to whatever load the system is designed to drive.

2.MPPT solar charge controller - Main features

In any applications which PV module is energy source, MPPT solar charge controller is used to correct for detecting the variations in the current-voltage characteristics of solar cell and shown by I-V curve.

MPPT solar charge controller is necessary for any solar power systems need to extract maximum power from PV module; it forces PV module to operate at voltage close to maximum power point to draw maximum available power.

MPPT solar charge controller allows users to use PV module with a higher voltage output than operating voltage of battery system.

For example, if PV module has to be placed far away from charge controller and battery, its wire size must be very large to reduce voltage drop. With a MPPT solar charge controller, users can wire PV module for 24 or 48 V (depending on charge controller and PV modules) and bring power into 12 or 24 V battery system. This means it reduces the wire size needed while retaining full output of PV module.

MPPT solar charge controller reduces complexity of system while output of system is high efficiency. Additionally, it can be applied to use with more energy sources. Since PV output power is used to control DC-DC converter directly.

MPPT solar charge controller can be applied to other renewable energy sources such as small water turbines, wind-power turbines, etc.

3.Compare to the traditional solar charge controller

The most traditional charge controller simply monitors the battery voltage and opens the circuit, stopping the charging, when the battery voltage rises to a certain level. Older charge controllers used a mechanical relay to open or close the circuit, stopping or starting power going to the batteries.Traditional Solar Inverters perform MPPT for an entire array as a whole. In such systems the same current, dictated by the inverter, flows though all panels in the string. But because different panels have different IV curves, i.e. different MPPs this architecture means some panels will be performing below their MPPT, resulting in the loss of energy.

4.Compared with normal solar charge controller by Schematic Diagram

MPPT solar charge controller Schematic Diagram: Picture 2 shows typical 12V battery solar charge system V-A curve.

Normal Solar Charge Controller: Solar Panel works at point A state, the solar panel working voltage is a little higher than battery voltage.

Charge Voltage: UA=13.2V

Charge Current:: IA=9.8A

Charge Power: PA=13.2*9.8=129.36w

Area in drawing: ①+③

MPPT Solar Charge Controller: Solar Panel works at point B state, the solar panel working voltage much higher than battery voltage.

Charge Voltage: UB=18.4V,

Charge Current:: IB=9.3A

Charge Power: PB=18.4*9.3=171.12w

Area in drawing: ①+②



MPPT Wellsee

Comparison: The power B is more than power A.

△P/ PA =(PB- PA)/ PA=32..3%

As a result of different manufacture of solar panels, different solar illumination intensity, different temperature, different efficiency of solar charge controller and so on. The effective power increase rate is 30%.

5.The benefits of MPPT solar charge controller

The benefits of MPPTsolar charge controller are greatest during cold weather, on cloudy or hazy days or when the battery is deeply discharged. Solar MPPT can also be used to drive motors directly from solar panels. The benefits seen are huge, especially if the motor load is continuously changing. This is due to the fact that the AC impedance across the motor is related to the motor's speed. The MPPT will switch the power to match the varying resistance.

6.The price of MPPT solar charge controller

MPPT charge controllers are more expensive that PWM charge controllers, but the advantages are worth the cost. If you can afford it, you should definitely use an MPPT charge controller.


Video Source: Youtube

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