Frequently Asked Questions

What size charge controller do I need?

The charge controller regulates the power between the solar panels and battery. They work by measuring the voltage of the batteries and the solar panels and adjusting the flow of electricity accordingly.

Therefore when selecting the right charge controller, the following pieces of information are critical:

• Wattage and voltage of the solar panel(s)
• System voltage set up (12v/24v/48v)
• Battery size (total ah)
• Specifications of the charge controller (voltage/amperage/nominal PV power)

Example 1: 12v system with a 405w/45v solar panel and 100ah battery

Charge controller

Minimum amperage = 10a (i.e. 10% of the battery ah)

Minimum input voltage = 50v (i.e. greater than the solar panel voltage)

For maximum performance, the charge controller current (i.e. nominal PV power) should meet the solar panel wattage in your system.

Options:

1. Victron SmartSolar 75v / 10a specifies 145w nominal PV power → cannot support the 405w panel in our example above. Need to go bigger.
2. Victron SmartSolar 75v / 15a specifies 220w nominal PV power → cannot support the 405w panel in our example above. Need to go bigger.
3. Victron SmartSolar 100v / 20a specifies 290w nominal PV power → cannot support the 405w panel in our example above. Need to go bigger.
4. Victron SmartSolar 100v / 30a specifies 440w nominal PV power → closest match to the 405w panel in our example above. Best option for maximising system performance.