DC-DC Converters And Maximum Power Point Tracking
A DC-to-DC converter or a voltage regulator is a device or circuitry that converts a source of DC from one voltage level to another. Most solar systems come with a special type of component that is able to convert DC to DC. In most systems, solar controllers play this role but other times, a separate DC-DC converter module is a required part of the installation.
Solar panels generate DC to be converted to AC for use in appliances by an inverter. A DC/DC Converter maybe installed per solar panel to help maximize the solar energy generated. It does this by performing a 'Maximum Power Point Tracking (MPPT)' per module. A DC-DC converter can boost the total solar energy produced by up to 30%. It measures the power and energy produced per module, as well as the temperature and voltage of the panel. They are able to shut down the panel's DC voltage when the temperature or voltage is too high.
They operate by taking DC input from the solar panel, changing it to AC and converting it back to a different DC voltage and current to exactly match the solar panel to the battery or inverter.
Examples of DC to DC converter are
1. Boost converter is power converter in which the panel DC input voltage is less than DC output voltage. That means the solar panel input voltage is less than the battery voltage in system.
2. Buck converter is power converter which DC input voltage is greater than DC output voltage. That means the solar panel input voltage is greater than the battery voltage in system.
DC-DC converters are often installed at the back of a solar panel. They solve the impact of shading conditions, module mismatch, temperature variance and aging mismatch of panels.
Maximum Power Point Tracking
Maximum Power Point Tracking is a way of extracting maximum power from solar panels under all conditions.
Solar panels are easily affected by changes in temperature and operating conditions that they produce a non-linear and impure output. An MPPT system is used to sample the output of the PV cells and apply the proper resistance (load) to obtain maximum power for any given environmental conditions.
The major principle of MPPT is to extract the maximum available power from PV module by making them operate at the most efficient voltage (maximum power point). That is to say: MPPT checks output of solar panels module, compares it to battery voltage then fixes what is the best power that panel can produce to charge the battery and converts it to the best voltage to get maximum current into battery. It can also supply power to a DC load, which is connected directly to the battery.
MPPT is most effective under these conditions:
Cold weather, cloudy or hazy days: Normally, PV module works better at cold temperatures and MPPT is utilized to extract maximum power available from them.
When battery is deeply discharged: MPPT can extract more current and charge the battery if the state of charge in the battery is lowers.
MPPT devices are typically integrated into a systems that provides voltage or current conversion, filtering, and regulation for driving various loads, including power grids, batteries, or motors.