MPPT: perturb and observe
A solar panel gives its most power at one point on its I–V curve. The ESP32 measures the panel’s voltage and current, nudges the load (the PWM duty on a dump resistor) one step, and checks whether the power went up. If not, it reverses. It settles hunting around the maximum power point.
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How it works
At 850 W/m² this panel’s maximum power point is 15.5 W at 17.0 V (910 mA).
The load the panel sees is R ÷ D: the tracker finds D ≈ 54 % to make it 18.7 Ω.
The PWM switch is simulated as its average, so the dump resistor’s own reading shows less heat than it really gets.
Try it on the bench
- Set the panel to 400 W/m² (a cloud): the power drops and the tracker walks to the new peak.
Parts on the bench
- Bench power supply
- ESP32 DevKit
- USB charger / port
- Solar panel
- INA219 current sensor
- N-channel MOSFET
- 3 × Resistor
- Electrolytic capacitor
In the course
Solar PV Systems, module “6 · Charge controllers: PWM and MPPT”.