Mar 02

Energy Accountability: Sources

Tag: energy efficiencymattholmes @ 9:56 pm

To document our energy budget, let’s start with the sources of our power. 

1. Sun: Solar Panels
Planned installation: two kyocera KC 85 panels mounted on top of the dodger, currently available at Wholesale Solar for $410 each.  They are 85W panels, and can be expected to output an average of 20Ah each, so 40Ah each day from solar.  Naturally, these numbers vary wildly depending on how sunny it is, how high the sun is in the sky, and whether our mainsail is blocking the sun from hitting them. 
daily contribution: 40Ah

2. Wind: Wind Generator
Planned installation: KISS wind generator, recommended by cruisers for its simplicity, quietness, and low startup speeds.  Cost: $995, not including the mounting of it.  Wind generators provide a decent amount of power in winds over 10 knots, and plenty of power when the wind is 15knots or above, but almost nothing below 10 knots.  So it is hard to estimate how much energy we’ll get from them on average.  The output curve of the KISS claims ~4A @ 5 knots (I’m skeptical) and 10A at 15 knots.  Let’s use a ballpark estimate of 4A for 10 hours a day average.
daily contribution: 40Ah

3. Water: Tow Generator
We own a tow generator that came with the boat–I do not know what brand it is or anything about it (there are no markings of any kind).  It mounts to the port toe-rail, and a 100ft line is tied to a propeller on a weighty shaft that drags behind the boat.  The propeller rotates, twisting the line, which then turns the generator.  From the various things I’ve read all over the internet, I expect it will produce 6 A at 6 knots of sailing speed, and in doing so slow down the boat by half a knot.  It’s difficult to estimate how fast we will be sailing on average–we’ll probably average right around 6 knots when we are sailing, so on passage we would derive 144Ah a day, but we’ll only sail on average one of three days, so call it another 40Ah a day.
daily contribution: 40Ah

Total clean energy sources: 120Ah per day

4. Diesel fuel: Engine Alternator
We have a "Silver Bullet" 165A alternator mounted on the engine.  After breaking the mounting bracket twice, the previous owners turned it down to a maximum output of ~110A.  This is considered a "high-output" alternator (stock alternators are 65A) and will produce the remainder of whatever our daily deficit ends up being, thereby balancing our energy budget.

Those of you out there who have more accurate estimates of daily production for the above sources, please share!

2 Responses to “Energy Accountability: Sources”

  1. Bruce Warren says:

    re the solar panels:

    I would suggest polling some actual users for their experience, such as the valiant user group. My reading would suggest the 40AH will be optimistic; you need to account for how much full sun the panels will see and any shadowing will have a dramatic impact on output.

  2. Dave says:

    Not sure this would be something you guys could use or if you have already heard of or seen it. But when I was readying about it made me instantly think of your blog.

    specifically the hand crank mini washer

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