Last weekend I was camping in with a couple of buddies in the open desert outside of Quartzsite, Arizona. The BLM land that we were camping on was dusty and windy, and on the second morning I found that my Portable Solar Panels were coated with a thin layer of dust.
Even a thin layer of dust like the one shown in the photo can impede the efficiency of the panels. And that means less solar power available for charging the batteries. Which means the batteries will take longer to charge. Which means less battery power for use in the Airstream.
Since the goal of using solar power is to keep the batteries as full as possible while camping away from shore power, you can see how that thin layer of dust could quickly become a boondocker's nemesis.
The 4-minute trick
Thankfully the solution is dead simple:
- Check your solar panels daily when boondocking
- If you see any dust, sand, leaves, or other debris on your panels, clean it off
All you need to do this is a piece of paper towel and a bit of all-purpose cleaner. You can also use a microfiber towel and water. (If you're looking for the latter, our friends at Almost Heaven Microfiber have designed dozens of microfiber products for RVers.)
What's the impact of cleaning the panels?
In short: a big gain in panel efficiency.
On most trips, I clean off the panels and leave it at that. But in Quartzsite, I had the chance to test the results and determine how much of an impact cleaning actually has. My test was conducted on two sets of AIR GEAR Portable Solar Panels, which are rated for 200 watts per set.
I went to sleep with dirty panels, knowing I'd run the test just after sunrise. It was January, and I took my first reading about 30 minutes after the sun had risen and while the sun angle was still very low. The panels weren't doing much yet.
As you can see from the following screen shot from my Victron SmartShunt, the batteries were receiving just 2.82 amps (33.8 watts) from the panels. Keep in mind that the SmartShunt shows the net power going into the batteries, after any 12 volt loads in the trailer such as lights, inverter, fans etc. The panels were actually producing about 90 watts combined, and most of that was being used in the trailer at the moment.
After taking the above reading, I did a quick wipe-down of the panels and that was sufficient. I worked quickly because I wanted to test the power load again before anything changed, such as sun angle or an appliance going on in the trailer.
Well, change it did. After the cleaning, the net power to the batteries jumped to 3.26 amps (38 watts).
Check out the screenshot below. That's about a 5% increase in overall power (4.2 watts / 90 watts *100 = 4.7%.) It's not a life-changing amount of power but definitely worth the small extra effort.
Tips for cleaning rooftop panels
Cleaning the panels is easy when you have a portable setup like ours. It's one of the things we prefer about portable solar panel kits compared to rooftop panels.
But if like many RV owners your panels are on the roof, we still recommend you clean them. It's less convenient (and can be a bit hazardous), but as you can see by my test results, worth the effort. Just remember never to climb onto the roof if you are alone. Always have someone there to spot you.
3 comments
Brent Dane
Since the DC loads in the trailer didn’t change after cleaning, I believe the increase in solar power was 4.2W (38-33.8) over the original 90W you said were originally being supplied, for an efficiency increase of 4.2/90*100=4.7%.
Rich Luhr
Brent D: Of course you’re right. Math was never my strong suit. I’ve updated the blog to correct numbers.
Jeffery Hammonds
This past Spring in the Black Hills I needed to clean the panels at least twice a day. Our little granddaughter would help me with the job of cleaning them. The next morning my wife said, “Where has the dish soap disappeared to?” After breakfast when our granddaughter and I went out to clean the panels, there was a coat of Dawn on them. As we cleaned the panels with water and made soapy suds I said to her, “Did you clean the panels without me?” She said, “Granddad, do you see how clean they are!”