Simple MPPT Circuit Simulating an Incremental Conductance Concept

An easy incremental conductance "type" of solar MPPT charger circuit is described right here.

The Design

The functioning theory of the following solar charger simulates the process of incremental MPPT voltage sensing, and regulating it according to the attached battery charging needs.

I have as well talked about this in one of my earlier articles where the design is in a guideline modification form.

The circuit directs the needed amount of voltage to the battery by sensing the highest power point of the solar panel, and by placing or keeping away from a couple of diodes appropriately in series with the supply path.

The working might be precisely known by researching the following instance:

As demonstrated in the circuit diagram, the total drop by the diodes when all are in series could well be around 20 x 0.6 = 12V.

Let's believe we certainly have a solar panel with optimum power point at around 26V and we want to employ this level for charging a 12V battery obtaining 14.4 V as the maximum charging voltage.

To start the MPPT performance we regulate the 10K preset of the IC LM3915 which can be a dot/display mode LED voltage indicator such that all its output turn out to be low (all LEDs ON) at the recommended 26V.

With this position the gates of all the mosfets turn out to be negatively one-sided to ensure that all of them stay shut off.

With all the mosfets shut off, all the diodes obtain in the path of the supply decreasing about 12 volts, which gets deducted from the solar panel total voltage, supplying about 26 - 12 = 14V across the battery, which happens to be pretty much the essential optimum charging voltage for the battery.

The above circumstance avoids the solar panel voltage from dragging down to the battery voltage level yet makes sure an optimal charging problems for the battery.

Currently believe the panel voltage falls by a few volts as a result of decreased sunlight or further equivalent problems.

This drop in the potential generates a proportionate drop at pin#5 of the IC which often switches OFF one or two of its outputs beginning with pin#10 and downward.

This forces the appropriate mosfets to perform and bypass a few diodes or even more thereby enabling a proportionate compensation for the battery under charge.

This guarantees that the battery is rarely missing out on the essential charging voltage even under unfavorable circumstances where the solar panel has lowered significantly. The operating also makes certain that even under undesirable problems the MPP of the panel is rarely decreased, and its voltage never dragged down by the battery under charge.

As mentioned above the IC LM3915 tracks and monitors the highest power point of the panel which can be in fact the optimum open circuit voltage of the specific panel under the provided conditions, and toggles the series diodes correctly such that the battery is imposed optimally even under toughest circumstances without negotiating with the highest power point of the solar panel.

The above design could be additional improved by adding this current and voltage managed tracker circuit in between the output of the circuitand the battery.

Parts List

All Diodes = 6A4
All Mosfets = 50V, 10A or similar, N-channel
All gate resistors = 47 ohms