PWM vs MPPT charge controllers explained

by SolarJunkie · 2 years ago 1,282 views 32 replies

Member

1 posts

Joined Jul 2024

6 months ago

#2854

Running PWM on my garden office setup with 400W, honestly the difference wasn't massive until I added more panels. MPPT made sense once I hit 600W+ though—the efficiency gains paid for itself within 18 months. Victron's tracking is solid. Depends on your system size really, not worth the cost below 500W IMO.

Kent Boater

Member

3 posts

thumb_up 7 likes

Joined Sep 2024

5 months ago

#2874

I'd add that the voltage mismatch is where MPPT earns its keep. Running 48V lifepo with undersized panel strings? MPPT tracks the optimal point across your entire array voltage range. PWM just hammers everything down to battery voltage, losing considerable watts on high-impedance strings. The Victron units handle this elegantly, though the upfront cost stings initially.

Brian Brown

Active Member

16 posts

thumb_up 38 likes

Joined Jun 2023

5 months ago

#2919

@CrispyWelder nailed it — PWM's fine until you realise you're leaving free watts on the table. I tried PWM on my boat and wondered why the battery wasn't happy. Switched to MPPT, suddenly it was like the panels actually liked me again. Voltage matching is basically magic if your panel string doesn't match your system voltage.