A novel hardware-software strategy for thermal chamber temperature control and PV energy optimization

This paper presents a hardware–software temperature regulation strategy for photovoltaic (PV) powered thermal
chambers, combining Maximum Power Point Tracking (MPPT) with a high-side NMOS power disconnection
mechanism. The proposed strategy disconnects the boost converter from the PV panel once the thermal setpoint
is reached, allowing the PV array to operate freely and supply excess energy to other loads. When the chamber
temperature falls below a predefined threshold, the converter is reconnected, and MPPT resumes to restore
heating. Experimental validation was conducted using a thermal chamber instrumented with eight temperature
sensors. Open-loop tests showed uncontrolled temperature variations up to 84 ◦C under fluctuating PV power
(50–254 W) and solar irradiance between 200 and 1200 W/m2
. Closed-loop experiments with a ± 0.5 ◦C hysteresis band demonstrated stable regulation from 30 ◦C to 70 ◦C, with full-cycle RMSE ranging from 0.68 ◦C to
1.04 ◦C and steady-state RMSE below 0.062 ◦C. Temperature rise from ambient (~17 ◦C) to 40 ◦C required
approximately 13 min at 110–125 W, while the transition from 60 ◦C to 70 ◦C required 12 min at 175 W,
reflecting the chamber’s thermal inertia. Settling times varied between 410 s and 720 s, and maximum overshoot
during heating was limited to 2 ◦C initially and 1 ◦C for subsequent 10 ◦C increments. Efficiency analysis of the
boost converter showed peak efficiency of 97.8% at low duty cycles (~24%) and output power (~110 W),
decreasing to 89% at higher duty cycles (41–44%) and output powers (~190–200 W). These results confirm that
the proposed approach provides robust thermal control and improved energy efficiency, making it suitable for
off-grid solar heating applications, including drying, sterilization, and controlled heat treatment, where both
temperature stability and optimal PV energy usage are critical.