A good story teller knows that a good story isn't the whole story. In many ways it's not what you include, but all that stuff you keep out that makes it fun to read. Put another way, do you really care whether I made pancakes or ate cereal for breakfast? So a lot of technical things got left out, but since this is (at least partly) a story about living with Solar, there are a few things I'd like to add so the curious can learn from my mistakes.
Sitting at the top of the list of details left out of the story is my much-maligned Mr. Heater Portable Buddy. In my story it failed and I didn't understand why, and I still don't understand the underlying problem. Now I've come home and surfed over to the Mr. Heater troubleshooting pages I've learned something.
Mr. Heater says their Portable Buddy works at altitudes up to 7000 feet. We were at and above 7500 feet when we were having heater problems.
I talked about the advantages of using a high-end solar panel
, but what does that mean and why are high-end panels better?
Most inexpensive solar panels are made using an "amorphous" coating that's cooked on to the panel substrate and looks like a coat of waxy black paint
. Amorphous solar panels have advantages: First of all they're cheap and serve as an entry point into the world of solar, and because they're cheap they make good "axillary" panels you can place away from your trailer where the sun shines brighter. In my book cheap counts when they're not screwed down because you won't feel quite as bad if they get stolen.
Those advantages aside, crystalline-structure solar cells offer advantages amorphous panels can't touch. There are two types of "crystalline" structure solar cells: "monocrystalline" and "polycrystalline" (also called "multicrystalline") panels, referring to the number of directions the silicone crystal structures in the solar cells generally line up in. "Mono" panels are more efficient than "poly" or "multi" crystalline panels.
Crystalline structure panels advantages are that they take up less than half the space that amorphous panels do to generate the same amount of power. An amorphous panel would have to have ten square feet (one foot by ten feet in size) to replace my existing four-square-foot crystalline panel.
Crystalline panels (and particularly monocrystalline panels) do a better job of making electricity under less-than-ideal conditions, too. All solar panels produce their highest energy output when they're pointed directly at the sun produce less energy as te sunlight falls on them at an angle, but crystalline panel power output falls more gradually as the sun sets, even at a 45-degree angle they still make substantial power where an amorphous panel's power output at 45 degrees is negligible. And crystalline panels don't have to have direct sunlight to pump out the amps. Parked under the shade tree in my front yard on a sunny spring afternoon my solar panel
pumped out almost an Amp of charging voltage. Amorphous panels produce no usable power under those conditions, when the sunlight comes in at a steep angle. This kind of performance is critical when your solar panel
is bolted to the roof of your trailer and its orientation to the rising and falling sun is hard to adjust.
Crystalline panels also last longer. They're designed to sit out under the full sun for thirty years before their power production drops below 85% of their original power output. Amorphous panels deteriorate to half their initial capacity in just five years under the same conditions, less if they become overheated due to poor air circulation, then they fail altogether.
Those disadvantages aside, an amorphous panel might well be your best choice if you keep it stowed away from the sun when you're not using it and set it up as a detached unit that you point at the sun. For Lynne and I, who have our solar panel bolted to the roof, the crystalline panel is a must-have.
50-watt crystalline panels cost $500+ new, so I'd suggest you (very carefully) shop for used panels on eBay where they can be found for under $300. Just be sure your seller has lots of sales and a high positive feedback rate and offers some sort of warranty that the panel will work when you get it.
Another important part of the solar system is the battery, otherwise you have no where to store the power your solar panel collects so you can turn the lights
on when the sun is down.
I could write a long article about batteries, but that'll have to be something I do on another day. For now I'll just list the advantages of the Optima-brand battery I've installed in our trailer and compare its advantages to a standard lead-acid "deep cycle" marine battery.
The Optima battery is an "absorbed glass mat" (AGM) type battery that keeps chemicals that are produced by the electrodes as the battery gets charged and discharged in close proximity to the electrodes. That makes it so that the battery doesn't spend a lot of charging energy moving chemicals around when the battery charges and discharges, so it stores more usable energy. An brand-new AGM battery can store and release electrical
energy at 99% efficiency compared to the 85-90% efficiency of a traditional battery, and that translates into more usable electricity from your solar panel.
AGM batteries are also more durable than regular deep-cycle batteries. They last longer partly because the "glass mat" that's embedded between the electrodes creates a padding layer that makes them less likely to deteriorate due to the vibration causes by towing your trailer, but that other thing the glass mat does, keeping the chemicals near where they were made, also prevents lead sulfate from migrating from one location to another, preventing the formation of battery-killing large lead sulfate crystals.
Not that Optima batteries won't sulfate. It's a major bummer: running our battery down as much as we did on our first and second nights in Yellowstone did cause our expensive Optima battery to sulfate. The loss of electrical
storage capacity in our battery is is pretty obvious. So when I came back home I went hunting for information to see if there was anything I could do about it.
What I found is a device called a BatteryMINDer, an intelligent charging system that sets up pulses of electricity at a specific frequency that vibrate and break lead sulfate crystals. It works something like a legendary opera singer who could hit just the right high note to breaks a lead crystal glass, but the BatteryMINDer uses electrical
frequencies instead of sound to do the job.
BatteryMINDer makes a grand claim on their website that their charger can restore a sulfated battery to near-new condition. I was pretty skeptical, but I did some reading on boating and telecommunications/computer websites (large computer and communications installations use lead-acid batteries to provide power to their equipment when a storm hits and the electricity goes out) and found a lot of people who did very careful testing to see the BatteryMINDer claims held up. The news was good, so I gambled and bought one for $50. I'll report back and let you know how well it works.
Last of all I want to tell you about some of the changes I think I need to make to improve our ability to dry camp using our solar setup.
The main thing about using solar power
is you have to make careful choices about how you collect, store, and use it. There has to be a balance.
Having, for example, 220 watts of solar panels that can collect forty to sixty Amp-hours of electricity on a normal day won't do you much good if you only have a single battery that holds just 30 amps of usable power. On the other end of the equation you can fully discharge two 30 amp batteries if you leave just two regular light
bulbs turned on for 24 hours.
In other words, you have to have balance.
We've already made great strides in reducing the amount of power our trailer uses by replacing all our light bulbs with LEDs. Regular light bulbs are amazing energy hogs: just two regular light bulbs draw more power (3 Amps) than our furnace does (2.8 Amps) when its running! Now our trailer lights
are all LEDs we can turn on all eleven (soon to be fourteen) lights, light the inside of the trailer up like an interrogator's chair, and still not use 3 Amps of power.
So we have to look to other ways to balance the system.
I have two choices: find some other way to cut our energy consumption or up the amount of power I can collect and store. Currently the major electricity hog in our trailer is the furnace, which draws 2.8 amps when it's running. (The water pump actually draws more power, 3.8 amps, but it only runs when someone used the sink or toilet, so its overall contribution to our power consumption is negligible.)
My preference is to double the size of our solar array from 50 to 100 watts. At 100 watts it'll be a lot easier to collect a full battery load of charge without having to park in "ideal" locations so our battery will more likely recover from unexpected energy drains like we had that first night at Yellowstone. If the battery had fully recovered by the time we got back to our trailer for our second night's stay I wouldn't have had a need to pull out the Portable Buddy to save on electricity. (And woud have lost out on a really good story to tell.)
I like this solution better than the alternative, replacing our furnace with a catalytic heater that uses no electricity at all. My problem with catalytic heaters is they don't heat the trailer evenly because they have no fan to blow the heat around. That's a big liability in a 19' trailer.
I have, however, come up with a neat way to make our furnace a little more energy-efficient and easier to live with. Something Lynne and I noticed when the battery voltage was low is the furnace runs more quietly. That has given me an idea: I think I'll design and install a controller that limits the voltage the furnace fan gets to around 11.5 volts. That'll do two great things: it'll make the fan quieter without compromising safety and cut the furnace's power consumption from 2.8 Amps down to around 2.5 Amps. :-) Not a big energy saving there, but the reduced fan noise makes the project very worthwhile.
(NOTE: DO NOT TRY BUILDING A FURNACE VOLTAGE REGULATOR UNLESS YOU REALLY UNDERSTAND WHAT YOU ARE DOING. AT 2.8 AMPS POWER DRAW AN INCORRECTLY BUILT VOLTAGE REGULATOR CIRCUIT CAN OVERHEAT AND CATCH FIRE. I also make not promises this is a good idea. Use it at your own risk.)