What we have on board:
MC4 silicone plugs
MC4 to 8mm Adapter for GoalZero
Beach bumming in Baja
The MorningStar SK12 has a really small footprint (important for our tiny battery compartment) and is as basic as it gets for a solar charger. It’s a PWM charger and is also waterproof and heat resistant. Both important for our current setup. With our two SunPower Flex 100 watt panels connected in parallel we do risk running the amperage too high for the charger (its rated for 12 amps and our panels together have the potential to reach 12.6 amps), but as the rep from MorningStar said, “It would be highly unlikely to have both panels at their highest optimal charging states at once…” So since Baja, we have been running both panels through it with no issues. I don’t think we will ever reach the optimal range for the panels because one is mounted flat on the roof which means it rarely sees its full potential. Que triste!
We spoke in depth with MorningStar about the two types of solar chargers, MPPT versus PWM, and the possible pros and cons of each. For our system, since it is so variable and so small the benefits of opting for MPPT would not be realized. However, if you have a larger system that is more stable/consistent (ie. a tiny house) an MPPT controller is a must. It helps optimize the ability to capture the solar energy throughout the day and is better at regulating larger wattage inputs.
Harnessing some power at Nevado de Toluca
MorningStar SK12 installed in battery compartment
Details of our 100 watt solar panel
We installed a waterproof gland in the roof to route the solar wires to the battery. We chose the Seaview Waterproof Aluminum Gland for 2mm-15mm diameter wire. Colin cut the hole in the roof and installed the gland. He is much braver and more confident than I when it comes to cutting holes into Peso’s shell. We have both the wires going through the gland and so far no leaks or issues. The cable is run along the roof line and down the side panel to the battery compartment.
We mounted one SunPower Flex 100 watt solar panel to the roof. Lucia fabricated the frame for the solar panel out of aluminum angle. We mounted the rack to Rhino Rack Rain Gutter Legs all with stainless security fasteners. All in all the rack, panel and legs weigh in under 10 pounds.
We run the two 100 watt panels in parallel and have blocking diodes installed on both since at times one may be shaded. We have two extension cables so that we can move one panel around and keep Peso in the shade. We use silicone plugs to keep water and dirt out of the extra MC4 sockets on the roof when we don’t have the extra panel out. For the Goal Zero, we have the 8mm to MC4 adapter and it works great with either the 50 watt or 100 watt panel.
Beach bumming in Oaxaca
Post Installation Thoughts
A year into the trip, the solar panels have been great. The extra 100 watt panel weighs in at 4 pounds and is easy to move around. We measure the incoming voltage on occasion and it is right about 20-21 volts when in full sun. We keep it stored under our mattress in a cotton sleeve. Sleeping on it hasn’t seemed to cause any issues that we know of yet. The one mounted on the roof is holding up well to the weather and elements; even with the occasional kamikaze fruit bombs that we have encountered along the tropical route. The 50 watt panel has been a great option for charging the Goal Zero. It is so sturdy and weighs in at 2 pounds. We probably would opt to carry two 50 watt panels and link them together because they are a bit more rigid and less likely to bend when being moved around.
We have only had one fault on the MorningStar charger and we believe it was because it got too hot. We disconnected the solar and it reset the charger. Since then we haven’t have any issues.