MPPT vs PWM Efficiency Tested

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Ever wonder why sometimes a PWM charge controller seems almost as efficient as an MPPT?
In this video, I put them to the test and found something surprising — the difference was much smaller than expected.

The reason? Solar panel temperature.
When panels get hot, their voltage drops, bringing them closer to the battery’s voltage. This makes a PWM appear more efficient because there’s less “extra voltage” for an MPPT to convert into amps.

Here’s what I tested:
Cool panel (35°C) → PWM efficiency: 74%
Hot panel (55°C) → PWM efficiency: 85%

An MPPT still wins in all cases, but the gap shrinks in hot conditions.

Whether you’re building an off-grid solar system or just curious about solar charging performance, this test will help you understand when a PWM can hold its own — and when an MPPT will pull ahead by a big margin.