Solar Controller

I will use a MPPT charge controller.  Based on my research this type of charge controller does a better job when it receives high voltage.  So my solar panels will be connected in series.   Connecting them in series adds up the voltage from each panel, and keeps the current the same.   If I connect them in parallel the voltage would remain the same and the current would add.

The negative of connecting in series is that the solar panels rely on each other.  If one panel has a bad cell, or low voltage from shading it may affect the entire system.

This design has a total of 400 watts of solar panels, comprised of two – 200 watt panels.  Each panel has a maximum output voltage of 20.4Volts, and current 9.8Amps.   Remember this is the ideal maximum.

Connected in series this will provide a maximum of  20.4 x 2 = 40.8 volts at 9.8A

Charge controller sizes are based on the voltage and current.   Victron charge controllers are named according to the voltage and current they can handle.  For example a Victron SmartSolar MPPT 75/15 Charge Controller will handle 75 volts and 15 amperes.  That size would be good enough for my solar panels.

I have decided on a Victron SmartSolar MPPT 100/30 Charge Controller.  Why?  Well. As of right now I do not expect to add solar panels.  But, in the future I might.  Plus, what if I want to experiment with connecting these in parallel, that would be 20.4 volts at 19.6 amps.  That would be too many amps for the 75/15 controller.

I don’t want to purchase another charge controller if I decide to double the number of solar panels.  There is enough room on the van for five 200 watt panels.  I  design and purchase components with flexibility in mind.   It may cost a few dollars more, but over time may save money!

DO NOT disconnect the battery while the solar panels are hooked up to the charge controller. Whenever I need to work on the solar panels I use the circuit breaker to disconnect them from the system.  The circuit breaker amperage should be no larger than the current of the charge controller.

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