MPPT vs PWM Solar Controllers Explained for Campervans
This guide explains the difference between MPPT and PWM solar charge controllers in campervan electrical systems. Learn how each controller works, when to use them and which one improves charging performance in a 12V leisure battery setup.
What is a solar charge controller?
A solar charge controller regulates the voltage and current flowing from the solar panel to the leisure battery. Without a controller, a solar panel can overcharge the battery and shorten its lifespan.
The two most common controller types used in campervans are:
- PWM solar controllers
- MPPT solar controllers
Main difference between MPPT and PWM controllers
| Feature | MPPT | PWM |
|---|---|---|
| Efficiency | Higher | Lower |
| Charging speed | Faster | Slower |
| Panel voltage flexibility | High | Low |
| System performance in winter | Better | Reduced |
| Cost | Higher | Lower |
How MPPT controllers work
MPPT controllers convert excess panel voltage into additional charging current. This allows the system to harvest more energy from the solar panel compared with PWM controllers.
- panel voltage can be higher than battery voltage
- charging current increases at the battery side
- better performance in cold weather
- better performance with longer cable runs
How PWM controllers work
PWM controllers connect the solar panel directly to the battery during charging cycles. This means panel voltage is pulled down closer to battery voltage, reducing overall efficiency.
- simple and reliable design
- lower purchase cost
- suitable for smaller solar setups
- less efficient with higher-voltage panels
Why MPPT controllers usually need thicker battery-side cable
MPPT controllers increase charging current on the battery side compared with the panel side. This often means the controller-to-battery cable must be larger than expected.
This is why cable sizing should always be calculated separately for both sections of the solar system.
Open Solar Cable Size GuideWhen to choose MPPT in a campervan
- solar system larger than 150W
- winter travel or low-light conditions
- longer cable runs from roof panel
- high-efficiency charging required
- lithium leisure battery installations
When PWM may still be suitable
- small single-panel installations
- very short cable runs
- tight installation budget
- temporary solar charging setups
Typical campervan solar controller example
| System Size | Recommended Controller Type |
|---|---|
| 100W | PWM or MPPT |
| 200W | MPPT preferred |
| 300W+ | MPPT recommended |
Use the Solar Cable Calculator PRO
Because MPPT controllers change current behaviour between panel and battery wiring sections, cable sizing should always be checked carefully.
Open Solar Cable Calculator PRORelated solar wiring guides
Choose the right solar controller for your campervan
Use the MKGT Solar Cable Calculator PRO to confirm correct cable sizes when installing MPPT or PWM solar controllers in campervan electrical systems.
Open Solar Cable CalculatorElectrical installation safety notice
This guide is provided as a general reference for understanding MPPT and PWM solar charge controllers in campervan electrical systems.
Controller selection depends on solar panel voltage, battery type, cable length, charging current and manufacturer specifications.