Solar Regulators Explained
While everybody knows that a regulator is required when using a solar panel or blanket, some don’t realise what the solar regulator does. We hope this article helps you understand the science behind these mystical beasts. Solar regulators play a vital role in turning the power created by a solar panel into usable power that your battery can absorb, however not all solar regulators are created equal.
PWM vs MPPT
A PMW (Pulse Width Modulation) controller draws current from the solar panel slightly above the battery voltage and sends pulses to the battery at the same current every time but varies the length of the pulses as the battery nears its maximum voltage. They are cheaper to buy and more reliable than an MPPT but they are less efficient, aren’t any good for a large solar setup and can’t handle 24V setups.
An MPPT (Maximum Power Point Tracker) controller draws maximum power voltage out of the solar panel, therefore providing as much power as the battery needs and is like a DC-DC charger. They are more efficient than a PMW as the MPPT will output the maximum amount of charge from the solar panel even on a cloudy day and when the solar panel heats up, something a PMW can’t do. While MPPTs are more expensive, larger and heavier than a PMW, they are suitable for a larger solar array as well as being compatible with 24V systems.
What does that all mean?
If you intend to connect a solar panel directly to your starter or auxiliary battery, you’ll need to ensure it has a solar regulator included. The reason is a solar panel can produce a charge between 12V and 21V which can damage your battery if it isn’t regulated. A good solar regulator will be dust and moisture-proof and will make sure that the correct charge is sent to the battery, and once the battery is fully charged, switch to float mode. Some solar panels (mostly portable solar panels or blankets) come with inbuilt regulators that are often very basic and offer little in the way of helpful information, simply some coloured lights that give you some idea of the charging stage. Having one with an LCD display is handier as then you can see things like the charge coming in, the current battery level and more.
If connecting a solar panel to the battery via a DCDC charger, the solar panel regulator won’t need to be used as the DCDC unit has an inbuilt MPPT controller installed to regulate the charge. The MPPT works out the load required from the solar panel to achieve maximum power from each cell and is especially effective in low-light conditions as it is intelligent enough to reset the load to a new point.
It is a good idea to have an MMPT regulator that is 30A or higher as it means you can add more solar panels to the system without worrying about overloading it. For example, there is a solar panel mounted on your rooftop tent that produces 6A and a solar blanket that produces 14A and both can be connected to the MPPT at the same time to send 20A to the battery. Solar panels are constantly being improved to produce more power to send to batteries so a larger MPPT will be able to manage higher inputs from the sun.
Smart power management systems like the REDARC Manager 30, Projecta Intelli-RV range and Enerdrive Power Systems have inbuilt MPPT solar charge controllers. The REDARC Manager 30 is also intelligent enough to prioritise solar power over all other power inputs, so you can always use green power to keep the battery charged.
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