Shop MPPT solar charge controllers for caravan, 4WD and off-grid battery systems across Australia. Compare 20A, 40A, 60A and 100A controllers for compatible solar arrays and 12V, 24V, 36V or 48V lithium and lead-acid battery banks.
Choose an MPPT Controller for the Complete Solar System
An MPPT controller manages power between the solar array and battery. Select it from the array's voltage, current and wattage, the battery-system voltage and the battery manufacturer's permitted charge rate—not from panel wattage alone.
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PV open-circuit voltage: calculate the total series Voc and allow for the voltage increase that can occur in cold conditions. It must remain below the controller's absolute PV-input limit.
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PV short-circuit current: calculate parallel-string current and apply the controller manufacturer's required design margin.
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Battery-side charge current: estimate array watts divided by charging voltage, then allow for conversion, operating conditions and the controller's published limits.
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Battery chemistry: confirm the controller has the correct profile or adjustable settings for LiFePO4, AGM, gel or flooded batteries.
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System voltage: verify support for the intended 12V, 24V, 36V or 48V battery bank.
Starting Estimates for 300W, 400W and 500W Solar on 12V Batteries
Using approximately 14.4V as a charging-voltage example:
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300W array: 300 ÷ 14.4 ≈ 20.8A before losses and design margin, so a suitably rated controller above this current is normally required.
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400W array: 400 ÷ 14.4 ≈ 27.8A before losses and margin, commonly placing the system in the 30A–40A class.
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500W array: 500 ÷ 14.4 ≈ 34.7A before losses and margin, commonly placing the system in the 40A–50A class.
These are starting calculations only. The final controller must also pass the array Voc, Isc, permitted PV wattage, battery charge-rate and wiring checks.
Compare Solar Panels by Wattage
Use the calculations above as a starting point while comparing our 300W solar panels, 400W solar panels and 500W solar panels. Always check the exact panel Voc, Isc and operating voltage because panels with the same advertised wattage can require different controller configurations.
Compare DC MONT MPPT Controller Sizes
MPPT vs PWM Solar Controllers
PWM can suit simple matched-voltage systems and smaller budgets. MPPT is generally preferred when the panel operating voltage is higher than the battery voltage, when using larger arrays or when greater system-design flexibility is needed. The controller specifications still determine what can be connected.
Build a Compatible Charging System
Pair the controller with suitable fixed solar panels, flexible solar panels or solar blankets. Complete the system with compatible lithium batteries or AGM deep-cycle batteries, correctly sized cable, fuses and isolators.
For alternator charging as well as solar, compare our DC-DC battery chargers.
MPPT Controller FAQs
Can I connect a 400W panel to a 40A MPPT controller?
Potentially, but the amp label alone is not enough. Confirm the panel Voc and Isc, the controller's maximum PV voltage and array wattage, the battery voltage and the manufacturer's oversizing rules.
Can one MPPT controller charge lithium and AGM batteries?
Many models support multiple chemistries, but the correct profile must be selected. Never assume a default setting is suitable for the connected battery.
Can I exceed the controller's maximum PV voltage?
No. The maximum PV input voltage is an absolute limit. Series-panel voltage and cold-weather Voc must remain below it with the required design margin.
Do I need an auto electrician or solar installer?
Professional installation is recommended where the system involves high current, permanent vehicle wiring, multiple panels, long cable runs or unfamiliar protection requirements.
