Tag Archives: charge

photo of 100 watt monocrystalline replacement panels

The Teardrop Gets a Solar Power Upgrade

Teardrop Trail Log: September 20, 2016

photo of MC4 solar branch connectors

MC4 solar branch connectors

After the unfortunate incident with the solar panel on our way to the Red Power Roundup, we were able to use shore power for the remainder of the trip. Disappointing, but not a show stopper. We had already determined that a single 100-watt panel was not enough for our needs, so I was planning an upgrade anyway. With a trip planned in late September, it was time to act. I ordered two new 100-watt panels, MC4 combiner connectors and additional MC4 crimp-on connectors. This would double our previous power capacity and allow for daytime use of a couple of small appliances including a crock-pot and solid-state cooler.

photo of Aluminum bar seals leading edge to teardrop

Aluminum bar seals leading edge to teardrop

Analysis of the incident and the remaining parts of the old panel made it clear that wind entering the leading edge had repeatedly flexed the panel causing it to fatigue and ultimately fail. It seemed to me that sealing the leading edge to the teardrop roof with a rigid mount would prevent this type of failure in the future. A trip to Home Depot secured an aluminum strip, and by drilling holes that matched the existing screw mounts, I could seal the leading panel to the teardrop skin. The leading panel then overlapped the other panel so it was also sealed to the wind.

photo of volt meter showing 13.2 volts

The new panels began working immediately

Once installed, the panels began producing power immediately. Although we currently only have about 80 Amp-hours of storage, the two panels can easily replace the day’s power use with 10 to 12 amp output in full sun. Also, by adding a 300-watt inverter, we are able to run a 1 1/2 quart crock pot during the day with power to spare. The next upgrade will be a larger battery.

The Ambassador was ready for a trip to Bob Sandlin State Park.

photo of solar panels on teardrop trailer

The panels overlap like shingles

photo of mounted solar panel

Solar Power on the Teardrop Trail

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.

photo of battery, charger and charge controller

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.

photo of Incandescent Bulb

Incandescent Bulb

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

photo of LED "corn" lamp

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.

photo of Mounting the panel

Mounting the panel