Solar Decisions

In my most recent post, I wrote, “Increasing my solar array to 800 watts isn’t going to make a significant difference when the sun just isn’t there.” This is true in the context of several cloudy days when I didn’t get much solar charging. However, two bright sunny days later, I’m finding that the 600 watts of solar on my roof is still not bringing in enough power to meet my needs. It maxes out at 250 watts and often runs closer to 100. My rooftop-mounted panels aren’t working anywhere close to their full potential because the sun is so low in the sky this time of year. By the time the sun comes up, I’m only at 12.8 volts or slightly less, which is as low as lithium batteries should go. Yesterday I ran my generator for a little while to put a little more boost back into my batteries, despite optimum solar charging conditions for this time of year.

I decided to buy another solar panel. But instead of mounting it to the roof, I’ll attach it to the stands I still have from last season, place it on the ground, and run it through my original DC-DC charger that I also use for alternator charging. This lets me use a different type of solar panel than the ones on my roof, such as Rich Solar’s 250-watt panel, which is on a Black Friday sale for just a few dollars more than the 200-watt panels that I already have on the roof.

I think the main reason why the 550-watt system on my old van worked well last season, but 600 watts on this van isn’t enough, is because my external panel was tilted toward the sun, not flat on the roof. Between the tilt and moving the panel a couple of times a day to follow the sun across the sky, that single panel boosted my charging capability a whole lot more than the numbers suggest. I never got rid of the stands when I liberated that 200-watt panel for the roof of Smokey II, so I’ll just use it again instead of selling it in Quartzsite like I’d planned to. Since I only need the extra power when I’m parked during the winter, it’s not a big deal to do it this way instead of mounting a fourth 200-watt panel to the roof. Besides, it, too, would suffer from the sun being low in the sky, not helping as much as this new panel should with its tilt.

Also, the BougeRV power station in my trailer came with a power adapter cord with the standard MC4 connectors that solar panels like these use. This means I can also use the new solar panel to recharge my power station without having to plug it into the van and drive somewhere. This is how I used to charge my old AGM battery through a cheap Amazon charge controller last year, except the power station has all the charging circuitry built in, so I can plug the panel straight in through the included adapter.

The other benefit of doing it this way is I’ll have space to install a second roof vent instead of a fourth solar panel on the roof. This will improve ventilation without the hassle of inserting and removing those vents in the front windows. This project will likely wait until later in the season since high temperatures aren’t going to be a problem for the next several months.