If you'd like to get more power from your solar panels, without any additional cost, this is for you! And this tip especially helps in winter months when the weather causes your solar array to be less productive.
Here we go...
When the sun's rays arrive at your solar panels, the more perpendicular they are to the array, the more energy will be produced (all other things being equal). Because of this, some companies have produced solar trackers that essentially move your solar array through the day so it stays as perpendicular to the sun as possible. But these devices cost a lot, and with solar power being so cheap these days, they usually are not worth the expense. However, it illustrates the impact that proper vertical angle can have.
While it's not practical to manually rotate your solar array from east to west each day through the day, there are some other adjustments we can make less frequently that can have a serious impact. In fact, it only takes as few as 2 adjustments per year to get most of the benefit.
You see, not only does the sun appear to move from our eastern horizon to the west each day, but it's also making a very gradual move each season. In the summer, the sun glides more directly overhead in the middle of the day. However, during winter it can be much lower in the southern horizon. The effect becomes more exaggerated the further north (or south) you go from the equator. The only place this stays the same all year is directly on the equator. For more details, see this post.
Thankfully, if you take this into account when setting up your solar system, you can easily make some occasional adjustments to maximize the power potential of your off grid solar array.
The Easy Way
If you choose your solar mount carefully, adjusting the angle will be a breeze. Here's a look at how easy it can be with a solar mount like the one I use from MT Solar:
Some other types of solar mounts can also be adjusted. For instance, if you build a false wall and mount solar panels using adjustable angle iron mounts like this:
With this option, holes are strategically drilled in the bottom metal runner at various locations to allow for the solar array to be tilted to different vertical angles. If you go this route, you may want to limit your number of adjustments each year since it isn't as easy.
And that brings us to the next question...
How Often Should I Adjust My Solar Panels?
You don't have to adjust them at all. And for many mounts (like roof mounts), you won't be able to adjust your array. But if you are able to adjust them, you can improve the power production from your array, especially during the winter when they struggle more.
Unless your array is super easy to adjust (like mine is in the video above), I suggest only adjust your solar array twice per year. Once in the spring and once in the fall. But if it's super easy to adjust (or you just enjoy doing it), you could do it once a month or even more (especially during Spring and Fall when the sun's arc is changing more rapidly).
Is It Really Worth It?
You might be wondering if adjusting your solar array's vertical pitch is really worth the work. And that's a good question. The answer depends on how difficult your solar array is to adjust and whether your solar array is oversized or undersized.
If your solar array is oversized--even for the winter months--then it probably isn't worth the work unless you have a mount that is super easy to adjust like mine. However, if you are undersized in the winter, then the bump you'll get could make a difference.
Here's the NREL Red Book data for our area, and you'll notice that the "Latitude + 15" row produces more solar power in the winter months than "Latitude" or "Latitude -15." What does that mean? It's a formula for the vertical pitch of your solar array, in degrees. In other words, if you are at 40 degrees of latitude, then "Latitude +15" would equal a vertical pitch of 55 degrees.
As you can see, the bump in power production isn't huge, but it can sure help--especially in those winter months that already have shorter cloudier days.
So the short answer to the question is, it depends. But for me, it's worth it.