-since you are already tracking wattage it's pretty easy to stay there when looking at your solar intake with 900 watts of panels.. to be conservative look at maybe getting 450 watts per hour averaged out over the hours of daylight.. So figure 8x450 = about 3600 watts total per day on average.. very rough numbers.. so you cold motor for 6 or 7 hours a day at 500 watts or so.. or 3 hours a day at 1000 watts. You have charging inefficiency to account for as well as loss in the controller and motor. If you run the motor during the day while the solar panel is producing you can pull most or all of that current straight to the motor instead of charging the batteries and taking the battery charging losses. It would probably give you a lot more range.
If you can mount your panels on tilting mounts so you can incline them toward the sun through the day.. even if only a little bit you should be able to increase the efficiency of the system by 20 to 50 percent over time. That requires you to adjust them several times a day. However if your on board at the time and motoring it should be no different that adjusting your sails as the wind changes direction.
scott
wrote:
>
> David,
> I'll typically run 10 or 15 miles around the lake before recharging, but the numbers seem to indicate that I could do 20 miles at 4.5 kt. running down to about 80% discharge. Keep in mind that this set of numbers were taken against a light breeze and chop to keep things conservative. Hopefully I'll get a chance to do some high-wind testing before the lake freezes this fall!
> Based on some previous tests, it looks like 20 miles plus is easily achievable at 4kt in calm conditions. At 3.5 kt over 30 is possible. At 3kt, maybe even 40.
> These are rough eyeball predictions, but I think they are reasonable. I need to cobble up a spreadsheet to lay it all out.
> Next summer I will install some solar panels which will extend the range some more, or allow me to be self-sufficient entirely and able to do maybe 10 miles a day at decent speed. I have room for about 900W rated capacity which, by my rough estimation, should give me 50 to 75 AH per day at my latitude (45 deg North).
> The prop is a 3-blade, and yes I have a belt reduction.
> Jim
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