A Magical Afternoon Of SNOW! Tucson, AZ

Posing in white

Flakes of white
My soul delight
Nina Fussing 2013

I had a completely different post planned for you today. A rather typical update of our last few days of nomadic adventures sprinkled with a few hikes, a couple of lovely sunsets…even a visit with some wonderful bloggers of feathery slant (all will be revealed in due time)

But then magic happened…

Surrounded by a winter wonderland…in the desert!

A white wonderland opened in the desert and everything I’d planned went out the window. The picture that painted itself before us was a flurry of snow’s delight, a dreamy landscape of winter dreams, an all-enveloping pillow of pure delight. THIS was blogging worthy news that just had to be shared right away. So we stayed home to take in the show and report the results. In the depth of the desert, in the heart of the wilds, we’ve experienced a snowy miracle. And OH IT IS GLORIOUS!

Now that’s a sight you don’t often see in the desert

We’re hanging at Catalina State Park just north of Tucson, AZ. We’ve been here a few days now and have done, well….absolutely nothing. It’s simply too relaxing, too naturally enticing to go anywhere. You know the type of spot. So we’ve been hanging, and hiking and generally basking in the mountains and the warm sunshine.

Until today.

White flakes linger on the mesquite trees

Snow on cactus

Today is a different day. Overnight a wild storm started brewing with a forecast for cold chills and snow levels falling to ~2000 feet. Our superbly handy phone app (WeatherBug) alerted us to the impending blizzard with an alarm yesterday afternoon, so we tucked everything away and waited for the show to start. The night wind blew but otherwise mother nature stayed her course. Then this AM the temperatures started dropping, grey clouds rolled in and the magic engaged. First a touch, then a light caress, then a snowy blanket deepened on the ground. It’s 2:00pm, the temperature is registering just around freezing and our cozy little RV is surrounded by crazy, splendid white wilderness.

Likely this picturesque delight will not last long. As I sit here blogging my last few words the sky has already opened to up a pale blue and the white dream is starting to melt. It may only have lasted an afternoon, but it was magical indeed.

First flurries of snow on the window

White Dreams

Calm after the storm

A prickly picture

A white pose

And an unusual RV view

RV Solar Part IV – Panel Tilting & Winter Solar Optimization

Paul and Alex go a-panel tilting

It’s been almost a year since we made the leap to solar on “the beast”. For those of you who missed the chair-gripping series I’ve got the whole exciting detail of how we decided what to buy and install in Part I (discovery), Part II (equipment) and Part III (installation). Since that time we’ve been geeking out and enjoying our panels through extensive dry-camping travels from FL to CA. I’m happy to say our panels have served us perfectly. On good sunny days we’re usually fully recharged on the batteries by noon plus the panels easily keep-up with our daytime power usage even if we’re on the internet all day. There’s honestly not much we’d change.

But there’s always an opportunity to geek out a little more. As days grow long and the sun sits lower in the sky we’ve started to think about winter solar optimization. Now solar panels actually like cooler temps (their output increases at lower temps), but they have a problem with angle which opens up all kinds of fun thoughts and experiments on tilting. And opportunities to blog, of course. So, here we go:

1/ Why Tilt Your Panels?

In winter the sun stays closer to the horizon

If you remember my lessons from last year, getting the best out of your solar system is all about minimizing loss. The same lesson applies to tilting too. The power density of a solar panel is always at its’ maximum when the solar panel is exactly perpendicular (at 90-degrees) to the sun. The further you get away from perpendicular the more power you lose and so the less power output you get. Since sun angle varies by both latitude and time of day that means your power output is varying all the time. So, how do you know what to do?

Well, in summer the sun will get pretty high in the sky and stays there for quite a few hours (as an example, here in Palm Springs it gets to ~70-degrees elevation) so your panel output will be pretty darn good even if they’re flat. However in winter everything changes -> the sun stays closer to the horizon (here it only rises to ~30-degrees) and your power output plummets. Sunearthtools.com has a really geeky cool page that’ll give you the exact angle of the sun any time of year for any direction and spot (just plug in your location):

Solar Diagram for Palm Springs, CA from Sunearthtools.com. The top line shows the sun angle in mid-summer, the bottom line for mid-winter.

How much of a deal is this, power-wise? In Palm Springs in summer you really don’t lose anything by keeping the panels flat whereas in winter you’ll lose more than 50% of your power output if you keep them flat. It’s HUGE!! To demonstrate this here’s another cool tool that’ll calculate daily flux (= an approximation of the total amount of energy hitting your panels) based on location, time of year and tilt.

2/ How Do You Tilt?

Our home-made tilt bars

The fanciest type of tilting systems are “sun trackers” that exactly track the sun all day long, but these are not exactly practical on a free-wheelin’ RV roof. Some RVers keep their panels mobile and just bring ‘em out to tilt/track the sun manually whenever they need them. With 6 heavy panels to lug around that wasn’t an option we wanted on our “beast” so it made a lot more sense for us to permanently attach the panels and look for other tilting options.

Our solution was to get the AM Solar mounts (highly recommend them, even if you aren’t going w/ AM Solar for the rest of their gear), and then add-on home-made tilting bars. Some basic 1/4″ aluminum stock from Home Depot cut to whatever length you want with holes drilled in (you can even drill multiple holes to have multiple tilt options). Combine with screw/nuts and you’re good to go!

3/ What’s The Best Tilting Angle?

If you’ve made it this far and manage to remember what we talked about in #1, then you know that what we’re looking for is to get your panels as close as possible to 90-degrees to the sun. The cool sunearthtools.com link will tell you what angle the sun gets to in your area, and some simple geometry will give you the optimal tilt angle:

At our current latitude and time of year we’re talking around 60 degrees tilt at noontime for best results. Now, obviously the sun moves diagonally across the sky during the day and rises/sets somewhat southerly in winter so that number doesn’t stay constant and the real (max. total energy) formula is a rather more complicated (the cool tool shows that). But if you face your RV East-West and tilt panels facing due south more or less at the 90-degree noon-spot you’ll get pretty darn close to getting the best out of the sun.

4/ Beware the Shadow Monster

See ma...NO panel shadows!

Tilting is just like everything in solar. You’ve got to make sure you avoid ALL shadows. Together with Marvin we were very particular when we installed our panels last year to make sure they had NO shadows from anything on the roof whether tilted or not, even with long winter shadows. I’ve seen shading models that show just 3% shading of a solar array can lead to a 25% decline in efficiency, with 10% shade producing up to 50% decline! The losses are dramatic and could mean the difference between a system that works and one that doesn’t. Even panels that have special “bypass diodes” (meant to help the shade problem) will suffer voltage loss for each cell shaded. Don’t be caught by the shadow monster!

5/ And Our Results Were….?

We conducted our little tilting experiment out in Owl Canyon BLM. Our tilt-bars only go to ~45-degrees so we knew we wouldn’t get optimal output, but we expected a pretty significant boost. Mid-morning with panels flat our 600W system was putting out ~20Amps. With the tilt we hit ~30 Amps, a 40% improvement. As the day wore on our boost got even better with the MPPT charger kicking up output to a stunning peak of~45 Amps at around noon (MPPT really shines with higher-voltage panels in colder temps). Coooool!

We plan to do even more detailed tracking experiments later this the winter and will undoubtedly share these exciting results with our readers, but for now this is a good start. There is also much more geekiness that can be done with solar so don’t expect to see the last of this sunny series.

Lessons in Cold-Weather Dry-Camping = Our Sierra Nevada Week-end

At least I have fur -> You should see the other guys!

It was going to be the COLDEST 4 nights we’d ever spent in the RV and for a wimpy-butt-chill-kitty like me that meant serious stuff. We were headed deep into the Sierra Nevada Mountains at about 7,900 feet near Mammoth Lakes. Day-time running temps were forecasted at a civilized 55-60°F  (13-15.5°C), but the nighttime thermometer was going to hit a MOST barbaric 18-20°F  (-8 to -6°C) and we were dry-camping without hookups {{swoon}} ! If it weren’t for the incredible views and stunning hikes (and the fact that everyone else thought it was a good (?!) idea) I wouldn’t be here, but as things stood I was ready to bear it out and take it as a learning experience. Very magnanimous of me, I thought…

It's all worth it for a view like this!

And a learning experience it was. As with all life experiences it turns out there were a few things we knew, but a lot we don’t know about cold-weather dry-camping. Now, we were lucky that it didn’t snow during our time in the Sierra’s and moisture levels were super-low (so, no real ice/sticking/condensation issues), but we did pick-up a few tid-bits for our next time (should I ever be so insane again) in the chill:

1/ Lead-Acid Batteries Lose Capacity In the Cold

Rough graph of Battery Capacity vs Temperature

Being an avid photographer I’ve always known that batteries go faster in the cold, but for whatever reason I hadn’t thought about it for the RV. Lead-Acid batteries are “cold-blooded” which mean they slow down (i.e. internal resistance increases) and they actually lose capacity as temps drop.  The loss is pretty dramatic and gets faster the more load you draw (something called Peukert’s Law). What that means practically is your 220AH battery bank may only be worth ~150AH at 32° F (0° C), and even less than that if it’s colder and/or you’re drawing a lot of power (e.g. running a furnace). This little tid-bit explained why our 440AH battery bank was more than 50% discharged after a chilly overnight spell, even though we only drew ~150 AH from them. It was colder and so they had less to give! For more accurate graphs see the Lifeline Battery Technical Manual (Appendix section, page 34)

2/ Windows Are Major Leaky Cold Points

I love having large windows for views in the RV, but they sure are temp-suckers. Being nice, handy radiant conductors in summer they heat up the rig to a greenhouse boil while in winter they leak warm air out and manage to allow nice, chilly leaks to ooze inside. Closing out those leaks can mean MAJOR heat savings and as temps dropped below freezing we quickly realized we were woefully unprepared in this category. Here’s a couple of ideas we put in our back-pocket for our next trip:

• Insulation Material – Our RV partners have a nice, handy foil-based Reflectix insulator on their big, front window and have Polartec material that they’ve sewed and velcro-attach to the inside of the smaller windows. Both these things made a huge difference in their rig (compared to ours) and we’re definitely stocking up on insulators before our next trip. Bubble wrap is another great, simple idea.
• Plastic Shrink Film – I’ve talked to hard-core cold-campers that swear by those window insulation films that you shrink-fit to your windows. The positive is that they really seal things up. The negative is that you can’t open for air. Not sure we’ll need to go this route, but it’s a handy tip.
• Better Shades – There are lots of shade options that do a much better job than the day/night jobs that we currently have in our RV. Old-fashioned Cellular shades or sleek, modern MCD shades can make a difference to both appearance and heat/cold tolerance. The MCD shades are on our “wish list”.

3/ Portable Heaters Rock

Our "Big Buddy" Heater

We have a Mr.Buddy (“Big Buddy“) that’s a great back-up/support heater to our furnace. We’ll often run it for a few hours before we go to bed to get a snuggly, warm temp and it turned out to be a major bonus for our Sierra week-end. You always, always need to remember to crack a window/provide ventilation with these guys (and make sure your CO detectors are working), but they’re portable, cheap and easy to use. The
Olympian Wave Catalytic Heaters  also get great reviews from RVers.

4/ Furnaces Can Suck You Dry

The fan in our furnace has a pretty significant power-draw (~10 Amps with both front and back going) and running it all night can easily suck us dry, especially when combined with other phantom draws and less battery capacity at low temps (#1). We managed to go below 50% batteries one night before we got wise to this one! We fixed this by switching to the portable heater (#3) before going to bed and sealing off our bedroom with only the back furnace on to keep us (and the pets) comfortable at night. As an additional back-up Paul set-up the auto-gen start on our generator to kick-in at 12.2V (~50% discharge point) on the batteries.

5/ Tanks Can Freeze, But It Needs To Be Reeeally Cold

It's not cold enough here for a tank freeze...yet

If you’re consistently in freezing temps you’ve got to think about tanks and hoses. Typically cold-weather RVers will insulate or disconnect/put-away hoses and keep tanks warm with a small heat source or padding. Since we were dry-camping our hoses were already safely in the bay, but we did make the mistake of turning on our tank-warmer one night which (once again) almost drained our batteries. Duh! In reality our day-time temps were warm enough that we needn’t have worried about any kind of tank freeze, and if we’re ever in a situation that we do…well…I think it’s time to move the rig.

Who wouldn't want to be here?

There are LOTS of other things that I’m sure we have yet to learn about. The good news is that our solar panels rocked the challenge (we managed to re-charge our batteries fully each day even though we didn’t bother tilting them), the cats did not turn into feline ice-cubes, and yours truly managed to survive with all fingers and toes in-tact. Oh…and it WAS worth it. The hikes, the views and the whole week-end rocked!