In an earlier post, we described a simple solar system for the our teardrop. With only a 15-watt capacity, we needed to upgrade and did so last year. We’ve gotten some questions about our solar power installation on the teardrop, and I wanted to share what we’ve done. This a work in progress, but during our recent Big Bend trip, we never hooked the trailer up to shore power (aka 120 volt hookups) and used solar power almost exclusively. It’s important to state our goals however, we didn’t intend to replace shore power. Instead, we wanted to extend the practical range of our trailer, making it possible to use primitive campsites for days at a time. This is where solar power can really shine (pun intended) on a small trailer.

There are several elements to a solar system. At minimum, a solar panel, a storage battery and some kind of charge controller are needed. Additions include 120/240-volt capabilities like battery chargers and inverters. Our system is almost exclusively 12-volt. With it we run lighting and have the ability to charge multiple devices such as smart phones, tablets, a laptop and digital cameras. We even have the ability to run a few high current 12-volt appliances like an electric tea kettle intermittently. Our trailer has a 7500 BTU air conditioner (this is Texas after all), but that must be run on shore power.

Charge controller in place

Broadly speaking, there are two types of charge controllers: Maximum Power Point Transfer (MPPT) and Pulse Width Modulation (PWM). Both have their advantages, but a PWM controller won in cost and efficiency for our particular application: hot, sunny climates and systems of 170 watts or less.  An article with a more complete comparison may help with your decision.

Here’s what we ended up with:

• Renogy® 100-Watt Monocrystalline Bendable Solar Panel (update: no longer available, but this panel is similar)
• Renogy® 10-Amp PWM Solar Charge Controller (update: no longer available, but this controller is similar)
• Interstate Group 27 Marine Deep Cycle/Starting Battery (available from Costco)
• Jensen JMP-800 75-Watt Power Inverter (plugs into a 12 volt outlet for occasional use)

Fortunately, our trailer was built with dual wiring: 12 and 120-volt. There is 120-volt power in both the galley and interior, and a 12-volt outlet is available in the interior. I added a 12-volt feed into the interior cabinets to power a Ten-Tec Triton II amateur radio. Most of the installation work involved mounting the solar panel on the trailer’s roof. The charge controller was mounted in the galley storage adjacent to the battery. The trailer was already equipped with a small charger, and it charges the battery when we’re hooked up to shore power. The solar panel can be removed from the roof and located away from the trailer using an extension cord. This way, we can park the trailer in a shady spot while the panel is located in the sun. The photos show the mounting screw installation process.

Incandescent Bulb

The trailer came with 12-volt automotive light fixtures and incandescent bulbs.

LED “corn” lamp

These were replaced with LEDs resulting in a 75% power savings. As I mentioned, it is a work in progress, and I would like to add a second panel. There’s room on the roof, and that would double our capacity.

Mounting the panel