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RV Daily Tips Newsletter Issue 887

Issue 887 • April 23, 2018
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RVing Tip of the Day

Reality check: Do you really have enough solar panels?
By Greg Illes 
Photo: Greg Illes

So you’ve decided to “go solar” – Congratulations!! No doubt you’ve read a lot about panel types and inverter technologies, and maybe gotten a few quotes. You probably have gotten familiar with the basic arithmetic of energy management by now too.
The advice you’ll typically see is to size your panels according to how much power you use each day, and of course this makes eminent sense. If you’re using forty amp-hours a day, then you need panel output adequate to recharge those forty amp-hours. If you figure five hours of good sunshine in the middle of the day, then your panels will have to produce eight amps, or about 100 watts. 8 amps x 5 hrs = 40 amp-hours
So that’s it, right? A 100W panel and you’re good to go? Not really. There are several reasons why the calculation, while entirely valid, is not so simple. Let’s review:
Sunshine availability – If you’re in the shade or it’s overcast, you’ll get less output from your panels. Even my shade-tolerant amorphous panels drop by 50% or more with heavy shade.
Panel angle – All panels have their power ratings at 90 degrees to the sun. This is never achieved in real practice, even with panels that can be tilted. Even if you get them aimed perfectly at 10 a.m., the sun keeps moving. At a 45-degree angle, you’ll get about 30% less power output.
Charge acceptance – Batteries will not necessarily accept all the available power. As they become more fully charged, acceptance declines. So not all the panel’s power will be absorbed. This physical limitation can only be compensated by more aggressive charging (more power) when the batteries are in a discharged state.
The bottom line is that a typical solar application might need two or three times as much power rating (and sunshine) as is actually used by the rig. This is because all the inefficiencies add up to only getting 1/2 or 1/3 of the rated panel power actually into the batteries.
To be safe, be conservative – figure an efficiency factor of no more than 50% for how much panel power you’ll need. If you’re still uncertain, make sure your system is designed for expansion, so that you can add a panel or two if needed. The photo shows my motorhome, using flex panels of 68W each. After going through the learning curve, I ended up going from two, to four, to eventually the six panels shown.
Don’t despair. Despite the uncertainties, you’ll love your solar system and won’t ever want to be without one again.

Greg Illes is a retired systems engineer who loves thinking up RV upgrades and modifications. When he’s not working on his motorhome, he’s traveling in it. You can follow his blog at

Read the last tipBetter use of space in your toy hauler.

Did you miss the latest RV Travel Newsletter? If so, read it here.

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Protect yourself and others from sharp edges of RV slideouts!slide-out-covers-655slide-out-guards-655
Cut your head just once on a sharp RV slideout and you’ll race out to buy a set of these so it never happens again! Camco’s Black RV Slide-Out Corner Guards offer a simple solution to the danger posed by sharp corners on RV slideouts (think about kids running by!). Simply place them on each corner of the slide to provide a cushion. Easy to install, no tools required. Learn more or order.


Keep grease out of your gray water system, but just in case …
Grease buildup in your gray water system? Prevent it by not dumping grease down the drain. But if necessary, work on fixing it by dumping distilled vinegar down the drain just before you hit the road – the sloshing will help cut the grease loose.

Use the correct extension cord for amperage!
With electricity expert, Mike Sokol 
Always use a heavy enough extension cord for the amperage you need it to supply. Here’s a chart showing the wire gauge needed for each amperage. Note that the smaller the gauge size, the thicker the wire and the more current it can carry. The larger the gauge size, the thinner the wire and the less current it can carry. Asking a wire to carry 100% of its capacity for extended times is dangerous and likely to cause overheating. In the pro world, we rely on the 80 percent rule where we size cables and circuit breakers to run at no more than 80 percent capacity continuously.

Do your fridge door gaskets need replacing?
RV refrigerator doors need to seal firmly to keep the cold in. Close a sheet of paper (or a $100 bill – kidding, $1 will work fine) in the door, trapping it between the door and the seal. Now pull the paper out. If it comes out easily, the door gaskets may be dried out. Get replacement seals from the manufacturer — they’re not difficult to replace. Some slide into a groove, others are held with screws, still others glue in place.

RVer concerned about overnight parking bans.

Multipurpose Microfiber Duster
No more car wipes to dry up — this duster replaces all interior car products. The 10-inch dusting head is big enough to get your dash dust-free quickly, but small enough to leave in your glove box. The back of the duster doubles as a scrubbing sponge. Great for interior or exterior use on cars, RVs, motorcycles or in the home! Learn more or order.


My Open Country
This site provides great camping guides for campgrounds, public lands and in parks. They feature gear guides and helpful reviews. There’s a little something for everyone here (including the kids).

Our RV Pet Vet, Dr. Deanna, used this website recently when her motorhome was nearly blown over by strong winds in Texas. This is a good one to keep bookmarked for those scary moments! 

Harvest Hosts
Looking for a unique camping experience? Harvest Hosts provides a database of more than 590 wineries, farms and attractions that all0w you to park overnight. Have fun!  

Check out the long list of great RVing-related websites from

mice-653Keep rodents out of your RV!
The positive reviews on this make it a best bet for keeping your RV rodent-free. This is the only plant-based rodent repellent registered for inside use by the EPA. It effectively repels rodents up to 100 days with a “woodsy” scent that’s pleasant to humans but offensive to rodents. It’s safe around kids and pets so no safety warning is required. 98% biodegradable. Used effectively by the RV Travel staff. Learn more or order.


Save a damaging rear-end collision with Superbumper
Gyro Gearloose reviews the Superbumper, and shows how his truck survived a rear end collision with virtually no damage while the vehicle that hit him was totaled.

See all of our videos on our YouTube Channel.

Full-timers: Need an RV Home Base?
Then you need Americas Mailbox! You’ll enjoy great tax advantages with your South Dakota “residency,” like no state income tax and low insurance rates (second lowest in the USA says the Insurance Information Institute). Many plans are available. View the video where RV Travel editor Chuck Woodbury talks with Americas Mailbox owner Don Humes. Or click here to learn more or enroll.


A convenient, compact fire starter
In RV Daily Tips Issue 884, we had a great tip from Ann Andrews for easy and economical fire starters from cardboard egg cartons and wax from cheese. Roberta Birch suggests the following: “Cotton balls saturated in petroleum jelly can be kept in a snack bag in your camp kit. They light easily and burn for a while.” Thanks, Roberta!

Egg cartons have even more uses
“We use egg cartons and the trays from coffee shops for starting campfires and for bug repellent. Light one, then blow out flames, place on a safe surface – the smoke keeps the bugs away.” Thanks to Dave Chessman!
Do you have a tip? Send it to diane (at) .

Protect your RV parts from rust and corrosion
T-9 is the RV technician’s choice for attacking corrosion, loosening rusty parts & flushing out old lubricants. It permeates metal crevices & seeps deep inside assembled components to leave a durable protective coating, lubricating without dismantling equipment. It won’t wash off in rain or mud. T-9 will not harm paint, plastic, rubber, fiberglass or vinyl. It can be used on engines, wiring, belts & is safe on electronics. Boeshield T-9 was developed by Boeing for lubrication and protection of aircraft components. Learn more or order.

Join us: On RVillageFacebookTwitterYouTube.

An RVing couple, both born the same year and month, were celebrating their 60th birthdays. During the celebration, a fairy appeared and said that because they had been so good she would grant them both one wish. Very excited, the wife said that since she had already visited most of North America in her RV, she would like to visit Europe. The fairy waved her magic wand and airline tickets instantly appeared. Then it was the husband’s turn. He paused for a moment, then said with a sly look, “Well, I’d like to have a woman 30 years younger than me.” The fairy waved her wand and, presto, he was 90!

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RV Daily Tips Staff
Editor and Publisher: Chuck Woodbury. Managing editor: Diane McGovern. Staff writer: Emily Woodbury. Contributing writers: Russ De Maris, Bob Difley, Gary Bunzer, Roger Marble, Deanna Tolliver, Mike Sokol, J.M. Montigel and Andrew Robinson. Advertising coordinator: Gail Meyring.

ADVERTISE on and/or in this newsletter. Contact Gail Meyring at Gail(at) .

Everything in this newsletter is true to the best of our knowledge. But we occasionally get something wrong. We’re just human! So don’t go spending $10,000 on something we said was good simply because we said so, or fixing something according to what we suggested (check with your own technician first). Maybe we made a mistake. Tips and/or comments in this newsletter are those of the authors and may not reflect the views of or this newsletter.

Mail us at 9792 Edmonds Way, #265, Edmonds, WA 98020.

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steve piccinati
5 years ago

I truly enjoy your newsletter. I have ordered several items over the past few months on Amazon from your web-page – how do I know that you are getting the “credit” for my orders?

Tommy Molnar
5 years ago

25 years ago I started with three 75 watt panels on the roof of our travel trailer, which fed two 6 volt T-105 Trojan batteries. An old school Cobra inverter fed the whole trailer. Fast forward to now. We finally got a new trailer six years ago and the first thing I did was add solar. This time it was three 125 watt panels with T-125 Trojans. This spring I added another 320 watts of panels, new Trojan T-145’s and a new Morningstar MPPT controller. The batteries won’t hold all the panels will deliver – most of the time. The reason I go for large solar array is for exactly what the article mentions. Cloudy days, rainy days, parked in shady places, etc. My old trailer’s panel;s could be raised to (hopefully) face the sun, but that meant climbing up on the roof to do it, both the up and down adjustments. Testing with my multi-meter showed that the difference was pretty minuscule, so our current set doesn’t move. Besides, at 72 I’m not in favor of climbing up and down that ladder anymore (ha). Oh, and that same old Cobra inverter (2500 watts) is in our current trailer and still doing fine.

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