Solar Panel Project Part 2

This past weekend, we installed all the wiring from the panel to the charge controller and from the controller to the batteries. We also drilled a hole and installed a cable through-hull to run the cable inside the boat. For the cable, we used a mix of 10 awg and 8 awg. We used 10 awg to make the connections at the panel because 8 awg would have been too difficult to route inside the junction boxes. We used 8 awg for the run from the panels to the batteries in order to have less than 3% loss according to these calculations:

Each panel watts = 140w

Panel rated voltage = 17.7v

140/17.7 = 7.9 Amps

7.9 Amps x 2 (2 panels) = 15.8 amps

Cable run length = 30-40 ft

According to this guide:

http://www.projectfreepower.com/solar-wire-gauge-awg-calculation

We need 6-8 awg cable in order to have less than 3% loss. We had a look at 6 awg, and decided that it was way too big to run and bend around inside the boat, so we settled on 8 awg. We found these super awesome step-down (8 to 10 or 12 awg) butt connectors that are also heat shrink, so we used those wherever we had to splice the cable. Here are some pictures of the second part of the project.

We taped large dark garbage bags on the panels to prevent from getting shocked when making the connections, but noticed that the panels were still producing quite a bit of amps and volts, so we put the cockpit cushions on top and water jugs to prevent the cushions from flying off.

 This is the hole hole for the cable, and the mounting holes for the cable through-hull

 This is what the cable looks like once inside the boat. We put a "drip loop" in case water gets in, it will not travel to the controller.

 This is a "service loop" in case we ever need to lengthen the cable or put in a junction box for another panel.

 These are the super cool 8-10/12 step-down heat shrink butt connectors. The picture taken after crimping but before heat shrinking.

 The negative cable from the charge controller goes to the load or ground side of the shunt.

 The orange cable is the positive cable from the controller to the batteries. There is a 25 amp fuse in-line, within 7" of the battery.

 Below is the junction box with the leads going to the next panel.

 This is what the cable through-hull looks like from the outside.

 Below is the junction box with one pair of cables coming from the next panel, and a pair of cables going towards the charge controller.

 Below is the open controller. The top set of leads goes towards the batteries. The bottom set of leads goes towards the solar panel array. There is also a 2 amp load going to the starter battery.

Here's the controller sealed up and putting out 14.6 amps. Below the controller is another 25 amp fuse on the positive cable from the solar panel array.