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During solar power harvesting process the power coming out of solar panels and juiced down to large amount of energy storage as battery banks or used on conventional loads has to be mitigated in order to obtain maximum efficiency. The process of mitigating the solar power it is done using power optimizers, power conditioners, power controllers and power regulators.

Is there a difference between a micro inverter and a power optimizer and what is that difference?

A micro inverter is mounted under a solar panel (or solar module) performing the role of a string or array inverter at panel level. A micro inverter receives DC power from that panel and moves that along the home run as alternative power straight from underneath that panel where it is mounted and takes care to get the max power possible out of that panel through MPPT optimization performed at panel level.

A power optimiser is a DC to DC power conditioner based on a strict follow of the IV curve for that specific module where it is mounted. In this way it achieves maximum power flow from the panel during sub-optimal module operating conditions caused by shade and soiling being able to recover over 50% of system level power loss. A power optimizer works complementary to a string or array inverter increasing site MPPT performances and allowing a full  fledge inverter mounted on the DC site downstream from the power optimizers to improve protection functionality respective  to add charger and connectivity functions.

What is the common benefit using either a power optimizer or a micro inverter?  They do have things in common. They are both mounted individual under a module and they do leverage the control at module level and they both eliminate the Christmas Tree Effect allowing modules to be parallel connected and in this way when one it is invalidated the rest of them are working full steam offering the best efficiency for PV - Plants.

What are solar power controllers?

They are the solar charge controllers. Solar power controllers are power  controller and optimizers at array level and they do have different ways to function that all depending of the type of application they support.They can be charge controllers with pulse width modulation (PWM) regulation and with integrated temperature compensation. Traditional solar power regulators featuring PWM (pulse width modulation) charging operate by connecting the solar array directly to the battery bank. When that array is connected directly to the battery bank, the array output voltage is ‘pulled down’ to the battery voltage. This occurs because the batteries are a very large load for the limited current sourcing capability of a solar array.

The other type of solar power controllers are the MPPT charge controllers. MPPT controllers ‘sweep’ the solar input to determine the voltage at which the array is producing the maximum amount of power. The controller harvests power from the array at this Vmp voltage and converts it down to battery voltage, boosting charging current in the process. They are empowered by a brand proprietary technology designed to quickly and accurately determine the Vmp (maximum power voltage) of the solar array. The main gain of MPPT charge controllers is the quantity of boost current the battery bank is receiving in accordance to the charge status.

Are they different?  They are trying to do the same job and the main difference between both is related to costs and type of application. PWM controllers are historically cheaper as MPPT Controllers and in the same time they do work better in low power (specifically low current) type of applications.

What are solar power voltage regulators?

Solar panel regulator should perform at least two operations: The obvious one is protecting the battery from overcharge at times when sun it is strong and little consumption, and the other is protecting it from excessive discharge in bad weather conditions. Both overcharge and deep discharge are harmful to a battery.

For regulating a solar panel's output, there are several possible ways. A linear series regulator can be used, but has the disadvantage of causing some voltage drop and having some internal power consumption at times when the sun is weak and the load is heavy. In most of the cases it is used a shunt regulator, which is inactive when sun is week and springs to life only when there is excess of energy.

The picture illustrates how a battery bank is dragging down solar panel voltage during the charging process using a PWM controller. Normal a 12V panel is working with a Vmp of 17V. During the charging process because of the sheer amount of amps juiced in by the batteries the voltage will lower value between 10V and 15V inside the hashed areas (the left hand site curve). In this way the system will have an energy lost marked on the power curve (the right hand site curve) between the pick Vmp = 17V and somewhere inside the hashed area. Normally we consider the constant energy lost between the pick at 17V and the upper level at 15V as constant system energy lost. Additional to that we will have an add on percentage of energy lost during the charging period. That is way the PWM Charge Controller are better serving in low currents type of applications, better used with a limitative number of batteries. Their low cost makes the application to have an affordable and attractive price.