What is a PWM regulator and when is it suitable?

A PWM solar regulator (Pulse Width Modulation) connects the photovoltaic array to the battery by “matching” the panel voltage to the battery voltage. It is a simple, robust, and economical solution for small systems where panels and batteries share 12 V or 24 V nominal and cable runs are short.

Advantages of PWM

• Low price and high mechanical/electrical reliability.
• Low self-consumption and straightforward operation.
• Perfect for compact kits in caravans, light marine applications, or cabins.

Limitations compared to MPPT

• They do not utilize PV voltages higher than the battery: lower production with “grid” panels.
• Lower efficiency in cold climates and with long cable runs.
• For 48 V or series strings, an MPPT is preferable.

How to choose your PWM regulator

• Battery voltage: 12/24 V automatic or selectable.
• Charge current (A): must cover the maximum current to the battery (PV W / battery V) with margin.
• Charge profiles: support for AGM, GEL, OPzS, and basic lithium compatibility (if specified by the manufacturer).
• Functions: display, load outputs, timers, communications (depending on model).

Typical applications

• Caravans and campers with one or a few 12/24 V panels.
• Light marine and boats with modest consumption.
• Cabins/shelters with lighting, small pumps, and basic electronics.

General specifications

Installation best practices

• Connect the battery to the regulator first, then the panel.
• Use a fuse and disconnect switch between battery and regulator and keep voltage drop <3% in DC.
• Set the battery profile (absorption/float) and activate the temperature sensor if available.

If your system is small, economical, and 12/24 V, a PWM will provide simplicity and reliability. To capture more energy and have flexibility in string design, choose an MPPT and complete with installation and monitoring accessories.