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We’re out of time, which is a good thing since it forces a decision on the solar array, hence this post. What you see in these images is what we’ll be looking at from the dinghy, the view with which we are most concerned.<\/p>\n
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As you will know by now, the array is aft.<\/p>\n
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There are three issues driving the layout. First, we want it all inboard when docking or anchored in traffic. Second, headroom is required coming up the steps from the swim platform. Third, minimized shading on the panels is important for output.<\/p>\n
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When the outer panels are folded down they are inboard of the rub rail, so we have good protection. And the headroom is fine.<\/p>\n
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This is a worst case scenario for shading. The boat is aligned with the sun off the bow. By a couple of hours after sunrise or before sunset there are no shadows.<\/p>\n
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If the hull is off the sun’s axis by 25 degrees there are essentially no shadows. This is a much simpler arrangement than what we have worked through previously, with minimal aesthetic impact at anchor.<\/p>\n
Theoretical output is roughly as follows. There are four panels with a rating of 320 watts each, so 1280 watts per hour potential output. We are assuming we can harvest 90% of this after allowing for shading and the fact these are flat rather than angled. This gives us 1150 watts net per hour. Then the question is one of how many “solar hours” we’ll be getting. This will vary from seven in the Bahamas in late spring to early summer, to maybe five in the summer in New England. So, something between 8000 and 5750 watts. To convert this to amp hours divide by your rate of charge, in our case 27.8 volts. This leaves us with between 206 amp hours \u00a0and 287 amp hours (at 24 volts). We are \u00a0reducing these figures by a further ten percent in \u00a0our own calculations.<\/p>\n
With our previous mode of cruising, where we were on the move a lot, the genset was rarely needed. The last two years we have been sitting more, with shorter engine runs between anchorages, and the charge cycle requires a bit of genset time. This by itself is not enough to warrant the solar array. But we are now more dependent on the genset\/inverter-charger system. We have the option of charging with the engine(s) at anchor, but this is not an appealing backup. With the output of this array we can double our time sitting before a charge is needed, and could easily drop \u00a0our consumption to match the solar output if required.<\/p>\n
The second consideration is when the boat is in storage mode. We think in many cases there will be close to sufficient output to run a freezer and the dehumidifier, so that if shore power is lost for a period of time it is not a major problem.<\/p>\n
The third, and final issue is that we think having this much power available from the sun is cool, and in many cases will eliminate the need for the genset, except for the clothes drying cycle.<\/p>\n
Now we just need to the panels in a timely manner (they are in high demand on huge projects).<\/p>\n","protected":false},"excerpt":{"rendered":"