Modular Junctions For Maximal Cabling
To keep power losses in a modest 16 volt circuit to a minimum, heavy duty cabling with a large cross-section is required (not to be confused with the maximum current it can carry for safe use). According to our calculations, these losses only become tolerable for our distances when cross-section gets to 16 mm2 or higher. But we can't connect a 16 mm2 cable directly to our solar panels, because it's too thick. That's why we hooked up to the solar cells using the 4 mm2cable delivered along with those panels. We kept this portion of the cable plant as short as possible, and inserted a modular connection junction close to the two solar panels, and ran the 16 mm2 cable from the junction box indoors to the PC.
Special solar power cables have a 4 mm² cross-section.
Our 4 mm² cables are only a little more than 5.5 feet long. Because we used two solar panels in our design, each of these segments carried half the total power. At maximum load, we lose 1.93 Watts. On the subsequent 39-plus foot 16 mm² segment, we lose 6.81 Watts. The total power loss across all segments is thus 8.74 Watts, for a total of 3.9% of our total power capacity.
Junction box for the two solar panels
We used a junction box to attach the two solar panels to the 16 mm² cables.
The junction box includes protective diodes to protect circuits from inverted polarity.
Connecting the cables
This junction box supports cable cross-sections of up to 32 mm².