The DC to DC Buck Converters work with two wires from the source in your case the 12 volt battery positive and negative that is charged by your solar cells. There are two wires to your model railroad equipment. A total of four wires. There are two 25 turn pots on the converter that adjust the voltage and current out. Unless you draw more than 8 amps from the output of the converter it doesn’t need fan cooling.
I have 5 of the convertors operating from a 12 volt 30 amp switching power supply, they will work on any DC voltage between 8 volts and 28 volts. The output of the converter can be adjusted to as low as 1 volt and as high as 30 volts at up to 12 amps.
I also use them on my workbench for testing and construction projects.
I have a MRC Prodigy DCC system and dinked around using a converter to power it. I adjusted the converter to 15.5 volts because that is the Prodigy power input. It worked very good with no problems what so ever.
I have them in service operating at 1.38 volts to power my 1.5 volt vehicle lighting, 5 volts for my Arduinos and Miller signs, 8.5 volts for hundreds of 12 volt Grain of Wheat bulbs on my layout. I operate all of my incandescent lights at 70% of the rated voltage for realism and longer life.
I also us the converters to charge 3.7 volt Lithium batteries, I can adjust the voltage and current separately to the battery manufacturers specs. As the discharged batteries voltage increases the current backs off, simple and accurate charging.
I bought my first of 8 DC to DC converters about four years ago and I haven’t had a single problem with any of them, best $4 investment I’ve made in a long time.
Mel
My Model Railroad
Bakersfield, California
I'm beginning to realize that aging is not for wimps.
