Solar Charge Controllers Explained

If you're setting up a 12V or 24V solar-charged power system, you'll need to include a solar regulator (otherwise known as a solar charge controller) in your setup. Without one, your battery won't last long (because your battery could blow up... seriously). 

In this guide, we'll cover:

• What a solar regulator is and why you need one
• The different types of regulators (PWM vs MPPT)
• How to size the right regulator for your solar system

Shopping for a solar regulator? Click here for Australia's largest range of MPPT and PWM solar charge controllers.

What does a solar regulator do?

A solar regulator acts as the middleman between your solar panel and your battery. 

Here's why it's essential:

• A 12V solar panel actually produces around 17-18V in full sun. If you connect that directly to a 12V battery, the battery will quickly overcharge. 
• Overcharging causes batteries to overheat, degrade, or even fail completely. 

The regulator's job is to: 

1. Control the voltage and current coming from your solar panel
2. Ensure the battery is charged correctly
3. Stop charging once the battery is full

In short: a regulator prevents your battery blowing up like a balloon, and keeps your system safe and efficient. 

Read more: Upgrading your dual battery system to lithium

Types of Solar Regulators

There are two main types of solar regulators:

PWM (Pulse Width Modulation) Regulators

• The cheaper option. You can find PWMs starting around the $40-$50 AUD mark. 
• Best for small, simple systems (e.g. a 12V panel charging a 12V battery).
• Directly connects panel voltage to battery voltage. 
• Limitation: you must use a 12V panel with a 12V battery (or 24V with 24V).
• Using high-voltage panels will result in wasted power. 

MPPT (Maximum Power Point Tracking) Regulators

• The better, more efficient option.
• Costs a little more than PWMs ($70-$80 AUD and up), but it's worth it for the additional features.
• Can take a higher-voltage panels and step them down to the correct battery voltage. 
• Increases charging efficiency by converting excess panel voltage into additional charging current. 
• Includes system monitoring and programmability (with brands like Victron and Alvolta) so you can:
• • Track exactly how much solar is going into your battery
  • Program charge settings for different battery types
  • Diagnose problems with error codes and live data

In most cases, we strongly recommend using an MPPT regulator, especially for larger or high-voltage solar setups. MPPTs are just the smarter technology choice. 

Example

PWM vs MPPT Efficiency

Say you have a 400W solar panel producing 40V at 10A:

• With a PWM regulator, your 12V battery would only see about 14.4V at 10A - roughly 144W of usable power. That's a huge loss!
• With an MPPT regulator, that same panel could be stepped down to 14.4V at around 27A - delivering nearly the full 400W to your battery. 

That's why MPPT regulators are the go-to choice for high-voltage panels and bigger systems. 

Read more: Cable and fuse guide

How to size a solar regulator

Choosing the right regulator depends on your panel wattage and battery voltage. 

Here's a simple calculation:

Solar panel watts ÷ battery charging voltage (≈14.4V for 12V systems, 28.8V for 24V systems) = required regulator amps

Example:

• 400W panel ÷ 14.4V = 27.7A → You’ll need at least a 30A regulator for a 12V system
• On a 24V system, the same panel would only need a 15A regulator.

Buying a Victron MPPT solar regulator? Visit the Victron MPPT sizing calculator 👉 https://www.victronenergy.com/mppt-calculator

Key sizing tips:

• It's fine to exceed the MPPT amp rating (you can exceed by roughly 30%), but never exceed the regulator's voltage limit. 
• Factor in if you may wish to add additional panels later on.
• Stay about 10% below the maximum voltage rating to allow for fluctuations in panel output. 

Read more: How do you size solar for your off-grid vehicle?

Read more: Calculating battery size for your caravan or 4WD

Which regulator should you choose?

PWM regulator

✅ Best for very small, budget systems

✅ Simple setups where efficiency isn't critical

MPPT regulator

✅ Recommended for most modern setups

✅ Extracts more usable power from your panels

✅ Allows flexibility in panel choice and wiring 

✅ Includes monitoring and programming features 

At Springers Solar, 90% of regulators we supply are MPPT models, simply because they're more efficiency, versatile, and reliable in the long run. 

👉 Check out our range of Victron and Alvolta regulators—from 10A units for camping setups right up to 100A models for large solar arrays.

Springers Solar | Your Trusted 12V/24V Components & Accessories Supplier

We only stock the best brands in the extra-low voltage industry for the best prices - you can trust that when you buy gear from Springers, you are setting up your system to perform long-term. We don't waste our time or your time with low-quality products.

With an in-house team of 12V/24V experts, we can offer advice and support as you set up your off-grid, off-road, or DIY battery system. We are Queensland-based and house our stock, so check out our online store here or visit us at Lawnton or Capalaba for in-store help.