Thursday, April 5, 2012

Thinking Solar

It's a cool, gray and rainy day outside my small home on wheels in North Carolina with temperatures trying hard to climb barely out of the mid-50s, drops of rain dance on the leaves of plants outside my door, and the only sound is heartbeat dashboard clock. The birds grown quiet in the rain A good day to talk about solar.

I've been on solar power for more than two years. A 65-watt Kyocera nestles in the luggage rack area at the back of my bus.

The 65-watt Kyocera solar panel.
This relatively small panel puts out 3.75 amps on bright sunshine. It is almost invisible from the street, making it less a target for theft and calling less attention to my home when I choose to be stealthy.

Romex wiring leads from the panel through the side air vents to a 7-amp controller inside the engine compartment below. From the controller power is fed to both the main battery and a deep-cycle sealed AGM battery under the jump seat inside.

I have found in my travels that 65 watts, or 3.75 amps, is all I need. Your mileage may vary.

Just as important as power input is power consumption. There are two main draws on my system. A 16-liter Engel fridge nestled between the front seats of my bus and my Acer Aspire One computer. Both consume minimal amounts of juice. And that is important.

From street level the panel is invisible.
Nominally the Engel uses 3.1 amps when running. (New models use only 2.6 amps.) If it were running all the time that would be about 75 amp-hours over a 24-hour period, overwhelming my system. But it doesn't. This morning I did a time test. The fridge cycled on for 75 seconds once every 30 minutes. The outside temperature was 57 degrees.

At that rate the fridge is drawing only about 4 amp-hours over a 24-hour period.  In warmer weather it will run more often of course. Still I have never known it to run more than 20 percent of the time.

I keep the fridge at a modest temperature, about 45 degrees. In hot weather I insulate by covering it with a towel. There is also a small 12-volt fan if needed to blow air over the coils.

But the real secret to minimizing fridge power consumption is understanding that small fridges need little power to maintain constant temperature but considerably more power to cool warm things down inside. So whenever possible only put things in your fridge that are already cold.

Raindrops outside my door.
When it comes to computers, for me small is better. I use Acer Aspire One  that uses little power (and takes up very little room). (A tablet might work even better but most of my work requires a keyboard.)

I replaced the original three-hour battery with a 10-hour one (good actually for about 7) and can now work long hours without recharging. In practical terms  this mean waiting until the sun is bright and the bus batteries are fully charged before drawing off power to recharge the computer.

How does all this work in practice? Surprisingly well. I always have extra power to watch the occasional DVD on small TV, read at night, occasionally make coffee in the morning and touch up clothes with a small portable steam iron that draws just 408 watts max and works like a charm.

But don't let thinking solar stop there.

A solar shower on the roof  heats up nicely any time the sun is out, providing warm water for showering and cleaning up. A bucket of sudsy water placed in the sun gives you plenty of warm water for washing clothes. A clothes line lets you dry them. Sleeping bags, blankets and pillows all can be aired out and sanitized in the sun.

You can even—so I am told—use the sun to sterilize water by putting it in clear plastic bottles and laying them lengthwise in the sun.

And the list goes on. Put a few tomato plants in pots and you have fresh food ....

Find a quiet place to watch the sun go down ...

...or while your coffee's perking watch the sun come up.


Or just get a book and a folding chair and sit outside in the warm sun and read.


Now the overcast skies that prompted this post are clearing.  Time to go outside and watch the monarch butterflies having their spring moments in the sun in the blood-red azalea bush full bloom.



  1. John, how do you implement your Photos? I detest having our Blog PICs hosted @ Picasa because of teh crappy way they display. I really like how your PICs display and that I can enlarge them to better view details.


    1. Thanks, John. Your suggestion worked so our PICs are now as we want them.


  2. At 65 W max, that's a nice, tight system. We also like having ours fixed - no climbing up and down to adjust.

  3. nice opinion.. thanks for sharing...

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  5. Please continue this great work and I look forward to more of your awesome blog posts.
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