Solar Power - We Have The Juice

 

210W Newpowa Solar Panel Installed on roof

I really need to go back and blog the electrical system as installed (vs as planned). I've been busy and not blogging, plus I wanted to wait until things were "done" before I blogged. Maybe another day. Today I'll cover the solar system.

I've mentioned that I installed an MPP Solar 1012LV-MS "all-in-one" inverter, battery charger, and MPPT solar charger. I got most of the system up and running a couple weeks ago, but this weekend I got the solar going so that I can charge the battery without being plugged into an outlet someplace.

The real driver for having solar power is the refrigerator. The Boles originally had an icebox, no fridge. I decided that I didn't want to use a 3-way fridge (AC/propane/DC) because it would require some sort of vent system for the propane and 3-way fridges generally aren't very efficient on DC power.

But going all electric drove some choices. I needed an efficient fridge. I also needed reasonable battery capacity. And even with all that I'd need to top off the charge partway through a typical 3-day weekend.

The math works like this. An efficient fridge (in my case a Norcold NR751) uses 6 amps when running. Reportedly it has about a 30% duty cycle. So it uses about 43.2 amp-hours per day. For 3 days that's 129.6 amp-hours. A 200Ah LiFePO4 battery has about 120Ah of useful capacity (cycling between 80-20% of capacity). So it's a little short for a typical 3-day weekend.

Since I hope to visit National Parks that typically don't have power to the campsites and I didn't want to run a generator, that leaves solar. I don't really need much, but if you're going to install a panel you might as well get the largest one that fits.

210W Newpowa Solar Panel

I considered a lot of different arrangements for the solar panel(s). I really wanted something as inconspicuous as possible. The flexible panels are very attractive from this perspective, but all my research indicated that they'd be a poor choice due to longevity and poor performance. That roof gets toasty even in the winter and having the flexible panel sit directly on the roof with no convection cooling underneath it would fry it quickly. Also power output from solar panels drops as panel temperature rises, so it's a double-whammy.

As a result I chose to go with a rigid panel. Because the roof curves you really need to mount the panel "east-west" and you also need a fairly narrow panel. That means you're stuck with 200W-class panels (at least right now). I chose the highest output I could find which was the Newpowa 210W.

I also chose a "drill-free" mounting option. I used the Renogy Corner Bracket Drill-Free Mount. Essentially you glue the mounts and panel in place. The recommended adhesive is Sikaflex 252. The online reports regarding the robustness of this mounting method are generally good but there are a few people who reported losing a mount (but not a panel!) somewhere along the road. Your mileage may vary.

One thing to note is that the Renogy mount is meant to be used on a flat surface and the Boles is curved. This requires some adjustment to the assembly directions and hopefully it won't reduce the strength of the mount too much.

I also used a Cutting Edge Power Solar Panel Weatherproof Cable Wire Entry that has MC4 connectors mounted on the shell. There are a million different cable entries available, but this was the only one I could find at the time that had the MC4 connectors. Note that I installed the cable entry when the trailer was down to bare metal because I needed to route the 10AWG cables through the ceiling and wall under the paneling.

T-Tocas 40 amp breaker

As mentioned, the panels are wired with 10AWG marine grade wire and enter the electrical system through a 40 amp T-Tocas resettable breaker. I really like this type of breaker because it can be used as a disconnect as well as a resettable breaker. I used several of them in the main power panel.

MPP Solar All-in-One Display Panel

Once I got the panel installed and the roof connections made I switched the breaker on. Like magic the MPP Solar device switched into solar-only battery charging mode (since I wasn't connected to shore power).

Xiaoxiang Battery Monitor App

I checked the battery monitor app and it showed the battery charging at 4.3 amps. That may not sound like much but when you consider the panel is mounted at an angle and it was pointed quite a bit off an optimal sun-normal aspect in November, I was quite happy. The trailer is parked east-west so I'll check the peak charging which in the Boles current orientation should be tomorrow around 11am.

I am keeping my eye out for a "solar suitcase" portable panel arrangement. I like the fixed arrange I've installed, but I know that I'll be looking to park the Boles under trees when camping any chance I get so having a remote panel makes a lot of sense. But that's a project for another day.