The boost converter circuit for solar cells can be employed for charging batteries from minimal voltage solar arrays. End results were gathered working with 3X3 cells that provide you with approximately 400 millivolts at 1 amp.
The pictured solar panel array includes 20 cells in sequence and yields around 8 watts at 8 volts in dazzling sunshine and was constructed on a 12 X 16 photo framework.
Performance of the boost converter calculated 87% and achieves virtually six hundred milliamps into a 12 volt SLA battery.
Proficiency decreases to roughly 72% with the use of 4 individual cells in range (pictured above) charging the matching 12 volt battery at around 70mA. The current was somewhat reduced owing to a few cracked corners.
One third examination was crafted from one cell at 0.4 volt recharging a 6 volt battery pack, however performance ended up being no more than 55%.
The 10Khz oscillator as well as control circuit accomplish energy from the battery which is being charged which need to be grater than 4 volts.
The output stage (mosfet and inductor) achieve electrical power through the solar panel array and deliver a recharging current by means of the schotty diode (VSK 330).
Productivity is enhanced using a 220uF capacitors put in between the input and output. A zener diode rated at 12V along with a 120 ohm resistor were included with safeguard the design from disproportionate voltage just in case the battery is turned off in the course of functioning.
Supplementary safety is acquired with the TL431 voltage reference diode which restricts the output voltage to 18 volts.
In the event that the output goes beyond 18 volts, the cathode of the TL431 collapses, quitting the oscillator to the point where the output drops below 16 volts.
While functioning, the PWM of the oscillating waveform was fine-tuned with the 100K pot for achieving optimum current for the connected battery.
This tuning is usually done by tracking the voltage across the 1.5 ohm resistor leads and fine-tuning for highest voltage.
This would be the optium adjustment wherein efficiency is strongest and highest possible electrical power is recovered from the solar panel array.
Control is not applied as a result the most effective positioning might require realignment as circumstances vary, illumination conditions, climate, battery voltage, etc.
A bit of deterioration arises in the 1.5 ohm resistor, possibly 5% which can be minimized with a realistic value resistor, or a milliamp digital meter with minimal resistance.
The majority of components used in this boost converter circuit for solar cells are relatively regular apart from perhaps the 5mH inductor.
I accustomed a ferrite torroid core picked up from a trash bag PC switching PS. The main core determines 1.5 inch outside diameter by 5/8 thicker.
The winding were eliminated and restored with 26 turns of the similar 18 gauge wire. The resistance determines 24 milliohms.
The inductor number is pretty resilient which enables be nearly all everything from 1mH or bigger in case the resistance was small while the core is unable to saturate for the peak current.
More substantial inductors could have decreased maximum currents nevertheless bigger resistance for the matching size.