When it comes to small solar energy systems for RVs and camper vans, ranging between 200 to 1000 Watts 12V systems, PWM (Pulse Width Modulation) controllers offer significant advantages over MPPT (Maximum Power Point Tracking) controllers.
One of the primary benefits of PWM controllers is their simplicity and compatibility with small-scale solar systems. Their design and operational mechanisms are less complex than those of MPPT controllers, making them more straightforward for personal or less intensive use. This simplicity also results in higher reliability and reduced maintenance issues over time.
Moreover, PWM controllers are more energy-efficient in certain scenarios. For instance, the SC-2030 Solar Charger from Bogart Engineering, a PWM controller, consumes only 3.5 Watts while delivering 30 Amps to a 12V battery bank. In contrast, a comparable MPPT controller from Victron can consume up to 30 Watts to deliver the same amount of current – this is the reason the heatsink of MPPT controllers are significantly larger. This stark difference highlights the efficiency and cost-effectiveness of PWM controllers in maintaining low operational costs and maximizing energy use from the solar panels.
When it comes to the physical setup of the solar panels, PWM controllers typically utilize a parallel connection of panels, enhancing the reliability of the solar array. Parallel connections are less susceptible to issues such as broken MC4 connectors, as a fault in one connector or panel does not compromise the performance of the entire system. Conversely, MPPT systems often require panels to be connected in series, where a single faulty connection can halt the operation of the entire string, presenting a significant risk, especially in environments prone to physical vibrations and movements, like in mobile homes or outdoor settings. Over 70% of the issues our customers experience with their solar systems are ultimately traced to bad MC4 connections.
Another practical advantage of PWM controllers is their fail-safe operational capability. In cases where a PWM controller fails, you may temporarily connect the incoming solar positive wire to the battery positive terminal on the controller, effectively bypassing the failed controller without further complicating the system. This workaround is generally safer in PWM systems, as the voltages involved are compatible with the battery’s voltage levels and would allow you to continue to boondock until you’re able to repair or replace the failed controller. On the other hand, doing so in an MPPT system can expose the batteries to very high voltages due to the higher voltages typically generated by panels connected in series, posing a risk of battery damage and safety hazards.
Considering these factors, PWM controllers stand out as a particularly robust choice for smaller solar setups. Their operational simplicity, efficiency, and reliability in various connection and failure scenarios make them preferable for users seeking a dependable solar solution without the complexities and potential risks associated with MPPT systems.