Solar, generator, or hookup?

[Sorry to those of you who are awaiting pretty pictures from our Death Valley trip this week.  I’m going to get to that later.  In this blog it’s only practical stuff.]

Winter is a good time to talk about all things electrical because it’s extra relevant now.  We like to camp off-grid a lot, and this time of year it’s tricky to make it work.

The problem is a double-whammy:  our solar panels collect a lot less energy due to low sun angle and shorter days, and our usage goes up because we need the lights and furnace for those long nights.

The easy solution is to go find some place with hookups, but our main criterion is to go where we want to go, not just where it’s convenient.  For example, we wanted to spend four nights in Death Valley, and three nights at Point Mugu State Park (Thornhill Broome beach), and neither of our chosen locations offers electricity.

A reader recently asked why we don’t just carry a generator rather than messing about with solar panels, inverters, battery banks, and all that expensive stuff. The answer boils down to personal style.  We had a nice quiet Honda eu1000i generator many years ago and it was a nice safety net when we really needed some power.  But we don’t have a pickup truck (so we are space constrained) and I hated having a gasoline-fueled appliance in the back of the SUV.

I also didn’t like having to run a generator when we were camped in a bucolic & quiet place.  The sound and fumes were just too obtrusive in those settings.  My friend Bert compares it to the yipping of a little dog–not really loud but just enough to gradually fray the nerves.

The final straw came during a visit to Organ Pipe Cactus National Monument, where (at least at the time) generator hours were during the peak of the day. We wanted to go hiking but didn’t feel good about leaving the generator running while we were gone. So we sat around the Airstream waiting for the batteries to recharge while the Great Outdoors went unexplored.

On that day we looked at the sun shining abundantly while the generator was throbbing away, and decided it was time to get solar.

Solar isn’t a perfect solution, it’s just the solution that fits our camping style best. It’s silent, free to operate, eco-friendly, and I don’t have to set it up or carry gas. It works anytime the sun is up, automatically. But I have to admit there are times when a generator boost would be helpful. Winter is one of those times, and this past week was particularly challenging.

That’s because we arrived in Death Valley with a problem.  A “phantom load” was nipping away at our batteries. If you haven’t heard this term before, a phantom load is a drain on the batteries that has no obvious cause. It’s different from a “parasitic” load, which is caused by certain electrical devices that never go completely off, like the stereo, the refrigerator circuit board, and the propane leak detector.

From our handy Tri-Metric amp-hour meter I have learned that our parasitic load runs about 0.9 amps.  When we arrived in Death Valley, that load mysteriously increased to 2.2 amps. That’s a real problem.

Look at it this way: a typical Airstream trailer comes with a pair of Group 27 batteries (that’s a physical size, not power capacity). They might each be rated at 85 amp-hours capacity. But because you are only supposed to discharge them to half their capacity (for longest life), your net capacity from two batteries is just 85 amp-hours.

A 2.2 amp constant drain means all of your useful power will be gone in about 38 hours–a mere day and a half—doing nothing at all. Anything you do to use power will only reduce the time till the batteries fail, so you might get just one day and night before finding you’re out of juice. I see people struggling with this all the time, and you can see their posts in online forums asking why their battery was dead after just one night of running the furnace.

(The furnace, by the way, pulls about 7-10 amps depending on model, which adds up to a lot of power when you consider how long it runs on a cold night. It’s one of the biggest DC power consumers in the trailer.)

In our case, I made things worse by leaving our new inverter switched on during the tow. That added another 0.4 amps to the constant load. And then, because it was cold when we arrived in Death Valley, we ran the furnace for about 30 minutes.

So despite being fully charged when we left Quartzsite, a few hours after we arrived at Death Valley our power was already down to 86%.  That made for a bad start to our planned 4-night boondocking trip.

That night I started tracing down the phantom load, and by pulling fuses and watching the Tri-Metric I was able to isolate it to a single circuit that powered the water pump, tank monitors, and external compartment lights. The problem turned out to be the front compartment light, which had become loose and was “leaking” voltage to the body of the Airstream.  If that doesn’t make sense, imagine a weak electrical short that isn’t quite enough to trip the fuse. I’ve never encountered this problem before or heard of anyone experiencing it, so I suspect it’s fairly rare.

I pulled the fuse overnight to stop the bleeding, and Kyle and I fixed that the next morning by relocating the light. But the damage to our power reserve was done, and the short sunny days of winter meant we couldn’t make up for it. This time of year the best our solar panels can do is generate about 25 amp-hours on a sunny day.

Our new Lifeline 8D battery has a capacity of 255 amp-hours, which gives us 127.5 amp-hours usable (remember, discharge no more than 50%). With a movie in the evening and a little furnace heating we were chewing up 45 amp-hours a day, so even with solar making up some of the power we were losing ground at the rate of about 20 amp-hours a day, which meant that after five nights we’d be done.

That’s actually acceptable for us. Our goal isn’t to have endless power, only to extend our boondocking time. To get five days from our battery and solar panels in the winter is just fine. (In the summer we do have endless power because of the long days, and have gone for weeks without plugging in.)

We cut the loss down by turning off the furnace and using our catalytic heater instead, and limiting use of the inverter and computers.  Since we’d been ravaged by the phantom load early on, Kyle plugged us into his generator for a quick 20 amp-hour boost.  The net result was that after our four nights in Death Valley the Tri-Metric said we still had 69% of our battery.

But since we were planning to follow up with three nights on the Pacific coast, where sunshine is not quite as guaranteed as in the desert, we spent one night at a full hookup campground to get fully charged. After a few days in the desert, it’s also nice to have a full hookup to clean up everything and everybody.

Now we are in our third day at the beach and it’s cloudy. I had to log a lot of laptop time these past two days, and we ran the microwave last night, so we’re down to 43% of our usable power. That’s OK too. We won’t run out before we leave tomorrow, and we’ve succeeded in our goal of camping next to the Pacific Ocean, so I regard this as a success.

This is just our story. It’s not the “best” solution for everyone. All that matters is that you can use your Airstream the way you want to. If that means going to full hookup sites exclusively, running a generator, or using solar panels, it’s all fine. Think about what you want to do and then you can decide the way you want to get there.


  1. says

    Refresh my memory, Rich. How many and what size solar panels do you have. Our 85 watt-ear is on our third trailer and is still doing fine for our needs.

    • RichLuhr says

      We have two 115 W panels on the roof. We probably use a lot more power than you because we have three people with lots of electronic gadgets and laptops.

  2. Teresa says

    Thank you for this. I’ve just purchased a new 25′ flying cloud – haven’t even taken her out yet and am stressing over generators or solar. Such an investment either way. Pro’s and con’s with either decision. I think i’ve made up my mind one way, read something else, and swing the other…ugh! I think your advice was to first upgrade the batteries? Do you have a suggestion? I am looking forward to boondocking and honestly this is stressing me out a little..and I’m going to need that relaxation!

    • RichLuhr says

      My suggestion is use the Airstream for a few months or even a year before making a decision. That way you’ll know your own camping style and needs better and can make the right choice for you.

  3. Ernie M says

    I have a 160watt Weekender solar panel from Go Power on my Airstream. Since I have it parked on my driveway and not in use nor plugged in, should I have it under “USE” or “STORE” to prevent the batteries from discharging? Or should I just have it plugged in at all times?

    • RichLuhr says

      If the Airstream is not in use and not plugged in, you should set the battery disconnect to STORE. That disconnects most electronics from the battery, but eventually the batteries will still go flat. For longer term storage tips, see suggestions in the “Storage & Seasonal” chapter and pages 175-178 of my Maintenance book.

  4. Fred Louwen says

    Hi Rich, we like boondocking as well. We have 200 W of solarpanel on the roof (which do not much in wintertime) and freestanding 150 W. This allows us to catch the sun, even as it is low in the sky.

    • RichLuhr says

      Yes, that is exactly why we will soon be offering a 120 W folding solar panel kit in the Airstream Life Store soon. Our kit will have some added features so it’s completely “plug and play” with no special wiring needed.

  5. says

    I love your mention of Trimetric meter to accurately monitor battery usage. Debbie and I agree completely on preference for quiet solar. Nine years in, we find the 1,000 watt generator is nice to have and rare to use. Your description of the annoyance factor of an ostensibly quiet genset is spot on.

    With 250 watts solar and 464 amp hours battery rating, we had much more battery than we could recharge in a day or two. This year I dropped two of the golf cart batteries. We now have 230 amp hours, enough for three or four days sans sun.