We have a long list things that need to be replaced on Alice, but if we can make it down that list within our budget, then near the bottom (but not at the very bottom) is a Solar Charging system. Since we’re in the middle of redoing the wiring, now is the perfect time to plan for our possible future Solar Panels and Solar controller.
Here’s what I’ve learned so far (bear with me, it’ll probably be a long and dense post):
Solar panels come in two main flavors (3 if you count Thin Film, but we won’t because they are more expensive and less efficient with little tangible benefit); Monocrystalline and Polycrystalline.
Monocrystalline panels are made from wafers cut from silicon ingots, and kind of sliced off the ingot like bread slices. This creates a hexagonal wafer of highly pure silicon. This makes for a very efficient solar panel. However it leaves a lot of waste, and the process can’t be easily mass produced, so Monocrystalline panels are usually more expensive. Also, due to the way Monocrystalline panels are constructed, a little bit of shade or dirt can break down the entire panel circuit. Meaning if we park Alice partially in the shade, we could lose an entire panel’s worth of charge for the day.
Polycrystalline panels are made from melted silicon poured into a mold, then cut into perfectly square wafers for the panels. This process makes the silicon less pure, and so the panels are less efficient than Monocrystalline ones, but it also makes them easier to mass produce with much less wasted material, so Polycrystalline panels are usually much cheaper. This design also makes them less susceptible to shade or dirt cancelling the panel’s charge, but as the sun sets they won’t be pulling in as much energy in the lower light scenario.
Since lower efficiency would mean the need for more panels, we first need to figure out how much power we can realistically make use of with our current battery bank. It doesn’t make sense to go with the Polycrystalline panels if we don’t have enough room on top of Alice to put them up.
Using advodna_dave’s excellent post on solar I’ve overestimated that, with the limited battery bank we have available to us, around 300 Watts of solar panels should be more than enough for our needs (about a weekend of boondocking), and should give us enough room to expand our battery bank if we want to upgrade to AGMs or something else in the future.
300 Watts of solar can be met with 2 – 150 Watt Monocrystalline panels, or 3 – 100 Watt Polycrystalline panels. Worst case, we needed to find room on Alice’s roof for 3 panels at 27′ x 60′. So this weekend I climbed up on on top of Alice and took some measurements.
It looks like we’ve got room for as many as 4 panels, and to me the fact that Monocrystalline panels can be put completely out of commission by some shade, combined with the fact that we have more than enough room for additional panels has me leaning towards Polycrystalline.
Now to find a good dealer, and start pricing out some systems. Our current estimates have us spending around $1,500 – $2,000 for the whole solar setup.
So if you have a recommended dealer, or have an opinion or questions to share on panels, let us know in the comments. At this point, we are just trying to learn as much as we can so we can make the most informed decision as possible.