Victron Energy MPPT Solar Controllers
While Victron Energy offers PWM chargers for low-priced systems the MPPT range has recently undergone significant discounts to remain the most competitive and feature rich solar controllers on the market. We, therefore, focus on the benefits of MPPT over PWM and standardise the Smart Solar range with its integrated Bluetooth communication for instant access to daily stats, charging voltages, currents, and long-term history via the Bluetooth-enabled Victron Connect software for smart devices.
Why so many variations? With different panel power from the small modules utilising 18v-22v Open Circuit Voltages, you can use the small 75 volt max input range for 3 panels in series. Why series? The higher voltages make better use in optimising the MPPT with global voltage settings that allow for shade variations from clouds giving and better year round yield. The larger 100, 150, 250 or 450 volt string voltages are optimised for larger strings where multiple solar panels are connected in series to generate high power. Victron Energy have one of the largest ranges of solar controllers on the market so there's something here for everyone in 12 volt for vehicles, motorhomes or security, 24 volt connected systems for cameras, security, marine or motorhomes. Even 36 volt for gate systems and of course 48 volt systems for communication towers, off-grid or modern vehicle systems.
How to calculate the voltage and charge current capacity of your controller
All the info you need can be found on the spec sheet of your solar panels.
Isc is the Short Circuit current (the absolute max before the panel breaks) therefore if you have a Isc of 10A then use the 10A value.
Voc means Open Circuit Voltage (the maximum volts when not connected to anything) use this figure when adding up total voltage.
Using Voltage if you connect in series which means positive of one panel connects to the Negative of the next panel and so on you can add up the total voltage (Panel A + Panel B =) total volts. This is the first number in the product code ie. 250/100 means a Max of 250 volts per string. If you are paralleling panels together the voltage doesn't increase, but the total current does.
The second part of the product code 250/100 is the total charging current (Amps) output. In a 12 volt system the calculation is (12 x 100A = 1200W), in a 24 volt system the same controller (24 x 100 = 2400W) could charge a battery bank twice that of a 12volt system within spec. This is typically why off-grid systems are 48 volt to utilise this characteristic of solar controllers. (48 x 100 = 4800W) That's the same as 10 x 480W solar panels. The catch is the voltage also needs to be under the max voltage limit of that first number "250 volts". With some juggling of the numbers you could build a parallel series connected array that maximises the charge output of the array quite easily these days given the scale, variety and power output of modern solar panels.