How to Choose the right MPPT Charge Controller

Why choosing the right solar charge controller is important

An MPPT (Maximum Power Point Tracking) Charge Controller is one that can deliver the best performance when it comes to charging up your batteries. It manages the charging of your batteries from the solar panels by converting a high voltage produced by your array to a lower voltage that your batteries can accept. A high-quality charge controller such as the one sold by Victron Energy could mean the difference in having an efficient solar system.

THE THREE PRIMARY RATINGS OF AN MPPT CHARGE CONTROLLER

RATING #1: BATTERY BANK VOLTAGE (V)

This is simply the voltage of your battery bank. When choosing the proper charge controller for your solar setup, it is important to determine that your controller can support your bank’s voltage whether it is 12V,24V,36V, or 48V.

RATING #2: SOLAR PANEL INPUT VOLTAGE (V)

The second rating of a charge controller is the maximum input voltage that it can accept from the solar array. This is by far the most important rating as under-sizing your charge controller’s input voltage could damage it and void its warranty. Typically this is given as a range i.e 20-150V or just a maximum voltage i.e 250V. There is no harm in inputting less than the maximum voltage that the charge controller can handle but going over can permanently damage the controller. A solar array of at least 18V is recommended for the proper operation of your charge controller

One external factor that you must consider in calculating your input voltage is the weather as cold weather can increase the voltage of your array. Most panels are rated in Voc based on standard test weather conditions of 25°C (77°F). You must base your calculations on the coldest it may get during daylight hours.

For example, if the Voc of your solar panel is 26.1V, and there are three connected in series, and it is 4°C on the coldest day, you would use the equation 26.1Voc x 3 in series x 1.10= 86.13V temperature compensated. That is great for a 100V rated charge controller but too high for a 75V.

RATING #3: OUTPUT CURRENT (A)

The third rating is how much current the charge controller can output. This is typically given in Amps. In order to check if the charge controller works for your system, divide the total wattage of your solar array by the voltage of your battery bank.For example, a 2000W solar array ÷ 36V battery bank = 55.6A. The rating of the charge controller should be at least 55.6A. For best performance, the total wattage of your solar arrangement should not be more than 15% of this rating. Doing this will allow the array to charge the batteries for longer during the day while making sure the controller is not working at its full rating all day.

Check out Canbat’s Victron collection of MPPT charge controllers. These controllers are smart and can string together to work in harmony for a solid-performing solar system.

For any questions about how to choose the right solar charge controller for your system, feel free to phone us or send an email to support@canbat.com. We also offer 24/7 chat support to ensure we are there for you when you need us. Our Canada-based team of battery experts is always happy to help!