Solar-Wind Hybrid Power System with Charge Controller and LCD Display

Most student renewable builds stop at one source: a solar panel wired to a battery through a basic controller, a setup that works in sunlight and stalls. Combining solar and wind fixes the dead hours, but it creates two engineering problems that single-source builds never face. First, the two sources cannot simply be paralleled — the stronger one back-feeds the weaker one — so each source needs isolation through its own blocking diode. Second, specific to wind: a turbine left unloaded when the battery is full spins faster, and small turbines can overspeed, vibrate destructively or overheat their generator windings. Commercial controllers handle this with a dump load, but they are sealed black boxes a student cannot open or explain. This project builds the controller itself: an Arduino-based hybrid charge controller that ORs a solar panel and a 3-blade wind turbine through Schottky diodes, PWM-regulates charging of a 12 V lead-acid battery, switches excess wind power into a dump-load resistor bank when the battery is full, and reports both sources' voltage and current plus battery state on a 16x2 LCD.

1. The solar panel and the wind turbine each land on their own input terminal block, and each source passes through its own Schottky blocking diode (approximately 0.3–0.6 V forward drop at operating current) onto a shared charge bus — neither source can drive current backward into the other.
2. The Arduino samples four analog channels: solar voltage, wind voltage and battery voltage through resistor dividers, plus one ACS712 current module per source leg, so the firmware always knows what each source is producing.
3. When battery voltage is below the absorption setpoint (nominally 14.4 V at 25°C, a trimmable design value), the controller drives the charge MOSFET with PWM at approximately 490 Hz default, delivering the combined available current into the 12 V lead-acid battery.
4. At the absorption setpoint the firmware switches to voltage-limited charging — the LCD shows steady voltage with tapering current — and then drops to float (nominally 13.6 V), holding the battery without overcharging.
5. If the battery is full (float stage, charge current below the tail threshold) while the wind input is still producing, the controller turns on the dump-load MOSFET, routing wind power into the resistor bank; the electrically loaded generator brakes the turbine instead of letting it spin open-circuit.
6. After sunset or when both sources fade, charging stops and the DC load terminal runs from the battery until voltage falls to approximately 11.1 V, when the load MOSFET disconnects it; the load reconnects automatically at approximately 12.2 V.
7. The 16x2 LCD refreshes approximately every second, cycling through solar V/I, wind V/I, battery voltage and the charge status flags, so the demo shows the whole hybrid behaviour live.

Tech stack:

• Arduino Uno (ATmega328P)
• Schottky diode OR-ing, dual input
• IRFZ44N · PWM charge MOSFET
• Dump-load MOSFET · resistor bank
• ACS712 · dual current sensing
• 16x2 LCD display
• 12 V lead-acid battery
• 3-blade wind turbine · DC generator

• [Dual-source hybrid charging] A 12 V solar panel and a 3-blade wind turbine feed a common charge bus through separate Schottky OR-ing diodes, so the controller charges from whichever source is producing — and from both together when sun and wind coincide — with no back-feeding between sources.
• [Wind dump-load overspeed protection] When the battery is full and the wind turbine is still generating, a second MOSFET switches the wind side into a finned resistor dump-load bank; the loaded generator slows down electrically, so the turbine never spins open-circuit at overspeed.
• [PWM charge regulation] An Arduino-driven power MOSFET regulates battery charging with PWM; the absorption (nominally 14.4 V at 25°C) and float (nominally 13.6 V at 25°C) setpoints are named firmware constants the student trims during their own calibration.
• [Dual-source telemetry on 16x2 LCD] The blue-backlit display cycles through solar voltage and current, wind voltage and current, battery voltage, and the active charge status (charging, absorption, float, dump-load active), refreshing approximately once per second.
• [Per-source current sensing] An ACS712 Hall-effect module on each source leg measures what the solar panel and the wind turbine actually contribute, giving the student real data for the solar-vs-wind energy comparison experiment in the report.
• [Load low-voltage disconnect] The DC load output disconnects at approximately 11.1 V and reconnects at approximately 12.2 V, protecting the battery from deep discharge when the load runs on stored energy.
• [Configurable setpoints, documented upgrade path] Charge voltages, the dump-load trigger point and LVD thresholds are editable constants in the firmware; the report documents optional upgrades such as MPPT on the solar leg, a larger turbine-generator, and SD-card data logging.

• Working solar-wind hybrid charge controller prototype (controller board, charge and dump-load MOSFET stages, finned dump-load resistor bank, LCD, current sensors)
• Small 12 V solar panel and 3-blade wind turbine model with DC generator
• 12 V sealed lead-acid battery
• Arduino firmware source code with commented setpoint constants
• Circuit and wiring documentation (dual inputs, diode OR-ing, dump-load stage, LVD output)
• Buyer-run calibration procedure (voltage-divider trim, current-sensor offset, setpoint trim)
• Solar-vs-wind energy comparison test procedure for the report
• Project report PDF (theory, design calculations, build procedure, testing methodology)
• PPT presentation for final review
• Viva Q&A preparation document (diode OR-ing, PWM charging, dump loads, lead-acid charge stages)