I have researched wind generator for Kahuna 6, and have yet to find any reliable wind solution that is economical and not overly large.  The Rutland 504 wind Generator is small, but it produces very little electricity.  with a steady 10Kt wind it will only produce 3 watts of power.  That is enough to trickle charge and maintain your 12V house bank, but it is an expensive trickle charge solution. ($500).    For 1/3 the cost you can purchase a 50 Watt Solar kit that will do the job, with a smaller footprint on the boat.   As an example.    the Rutland 504 assuming constant 10Kt winds will produce roughly 72 watts of power in a 24 hour period.  More than enough to trickle charge, but insignificant to recharge while using the boat.  a single 50 watt solar panel even with a partly cloudy sky, will in that same 24 hour period produce on average 150-200 watts of power.  Basically twice the power produced for 1/3 the cost.  If Trickle charge is all you want to do, then a single 25 Watt solar panel at even a smaller footprint, and less cost will equal the output of the Rutland 504.  Clearly there are larger, and more costly wind generator options ( Rutland 910,913/914), or Air X, but with 46" blade rotation, on a small boat, they are not particularly practical, and are overkill if all you want is trickle charge to maintain the battery.

Not sure your what your objection to solar is, but for what you want to do, solar is the smallest, cheapest, easiest to install, and most efficient solution currently available.

Ehrich Rose
Kahuna 6
Hull 281

A panel will produce approximately 5 hours, 75% of its rated output per day. A 50W, 12V panel will produce 5*.75*50/12 Amp/hours/day, 15.6 Ah/day. An Amp/hour is a better measure of power because batteries and panels can have various operating voltages.
I have over 10 years of data that I check randomly on solar panel output to support this approximation. Our home has 2.3KW of panels on it, with a constant southern exposure.

“Well, a man is going to do what he is going to do.”, Hondo, 1953

Mike,

You and I agree on the amount of power (electricity) expected from a 50 W Panel.  I said 150-200 watt hours....which in 12V amp hours is  12.5 to 16.6 Amp Hours per day. No disagreement with your calculations, and at risk of appearing to be a pointy headed snob, I must disagree with your statement that "Amp/hour is a better measure of power because batteries and panels have various operating voltages."  That statement can be misleading or confusing.  Amp hours are a measure of current.  and Power is defined by Current and Voltage.  Which is the definition of a Watt hour.   as an illustration...a 50 watt solar panel will produce roughly 3.8 AH/Day, 7.7 Ah/Day or 15.6 AH/day depending on the voltage of that panel.  but that same panel will always produce the same185 watts hours/day regardless of the voltage. Which is why the size of  solar panels are measured in Watts not Amps. Unless there is an agreed upon understanding of the voltage of the system Amp/hours can create confusion when discussing the "amount of Power".   As an example my brother in law and I talked passed each  for 30 minutes because he was arguing an appliance required only 3 amps, so his 100 ah 12V battery should have no problem using an inverter to run the appliance for 12 hours.   But the appliance used 3 amps @ 120v, which is 30 amps at 12V.   and that is quite a big difference.  Had he understood from the start that his appliance required 350 Watt hours, he would have immediately known the limits of his 1200 watt hour 12V battery.

Electricity is confusing because of the relationship between watts, Amps, and Volts.  And then we tend to muddy the definition by using terms such as "amount of energy, or Measure of Power when using these terms.   I prefer to use the example of water as an analogy to help explain the relationship.     For electricity a Watt Hours is the amount of electricity used in one hour.  For my analogy, a watt hours is a fluid ounce in a bucket. Volts would be equivalent to the diameter of the water pipe, and Amp hours is the water pressure in that pipe.   So to move 100 ounces of water in a one inch pipe it takes twice the pressure to move 100 ounces in a 2 inch pipe.   Just as to move 100 watt hours of electricity it takes twice the number of Amp hours in a 12V system than a 24V system.  I have found that the best way to design an electrical system is to first decide the requirements for how much electricity (number of watt hours) you will need to move.   Then once you know that requirement, determine the most efficient and cost effective way to do that.   Just like when moving water through a pipe, the higher the pressure, the stronger the pipe has to be.   With electricity the greater the AMP hours, the thicker the wire has to be.   So if needing to move large quantities of watts, the higher the voltage and lower the AmpH, the better.  This is why electric cars are normally 96V systems, and small electric outboards are 48V systems.   For most of our boating requirements, 12 V is sufficient, because LED lights, Chartplotters, VHF radios etc, normally operate with less than 30 watt hours of requirements.   Compare that for example to a microwave oven that requires 1500 watt hours.   Hence why you will not find 12V microwave ovens. 

This is why if someone asks how much electricity do I need or can produce...it is better to respond in terms of Watt hours rather than Amp hours.   Just as if someone asked how much water do I need, we would respond in terms of fluid ounces not water pressure.

Enrich,

Mike,

Great discussion, we have two different ways of getting to the same place, but we are in agreement as to the final outcome.  I think you may want to relook, your 12V system plan, for a couple of reasons.  Given your need of 200-220 12 V AH/D, I think you will only need 600-700 Watts of solar panels. About half of what your were indicating.   I will do the calculations using AH/D since that is what you are most comfortable with.  

A rule of thumb when using 12V AH/D calculations is to use the factor of .31-.34.  This factor has a range depending on several variables, and best way to determine which is best for your particular situation is frankly just to test your set up.   But given your calculations we will use the factor of .31.    Multiply the factor (.31) by the watts of your solar setup to determine 12V AH/D.  So as an example back to our original 50 watt solar panel.....that would be .31 X 50 = 15.5 AH/D.   So doing the algebra, if your requirement is 200-220 12V AH/D  , you just need to divide 200-220 by that factor to determine the number of solar power watts you will need, 220/.31 =645.   220/.31=709.    Nothing wrong with having 1200 watts of solar panels, but that would produce 372 AH/D.   Overkill, especially when real estate is critical.

The reason you do not need to double your solar capability, is that although solar panels only work in the day, your 200 AH/D draw occurs during a 24 hour period.  I would argue, that to maximize your set up, it would be best to ensure that every day at 5 pm to take a reading of your batteries and see if they are 100%.  At night they will draw down for arguments sake we will say 100 AH during the night, so that at 8 am, your 600 AH battery bank would only have 500 AH left.  But then that is when the solar kicks in.   Although you will drawdown another 100 AH from 8am until 5 pm, you will also be producing 200 AH from the solar.....enough to cover the draw down, and to replenish the missing 100 from the night before charging your battery back to 100% at by 5 pm.   If you had 1200 watts of solar as an example, you would produce 345 AH from 8 am until 5 pm, but you would only use 200 of that  345 AH (100 from night before, and 100 during that day) .  as a result, your battery would be full maybe as early at 1pm, and the solar controllers would switch to float, and essentially dump all of that excess AH, that your solar is producing from 1pm to 5 pm. 

This is why the size of the battery bank becomes part of the design feature.   I am not aware of any real hard and fast rule, but I always recommend a Lithium Battery bank to be 3X the daily requirement, and an AGM battery bank to be 4 X the daily requirement.  So in your case minimal 600 AH 12V Lithium Bank, or 800 AH 12V AGM bank.  That gives you plenty of capability to draw down the battery at night, and to provide sufficient reserve for those cloudy days when Solar is providing 40-50% of what we template. 

In my case, on Kahuna 6, I have a Daily draw of 125 AH/d.   My battery bank, since I am all electric in Galley is 600 AH 12V Lithium.  and my Solar is 300 Watts.  3X 100 panels (parallel).   I have found through testing that my factor is .35.   I produce roughly 105 12 V AH/D from my solar.  One reason for this is I have two panels fixed on an arch at the stern, and one panel that is mobile.  I can reposition that mobile panel based on location of sail, time of day, and angle of sun.  That allows me to really minimize shading and maximize that one panel.  None-the-less, I still run a 24 hour negative delta of about 20 AH/D.   To compensate, I bring a generator for longer trips, and I have a "large" Lithium house bank.   I have yet to go on anything longer than 10 days, but have only needed the Generator if I run my Air Conditioner which greatly increases my daily power requirement.  So I have never had an issue with insufficient power, even with a couple of cloudy days.

Finally, increasing the voltage of the solar panel does not shrink the size of the panel.   4x 100 watt 12V solar panels rigged in parallel require the same footprint as 4X 100 watt 12V panels rigged in Series to create a 48V system.   Or to put it in my terms a 4X100 watt panels produces the same number of watts whether rigged as a 12V system or a 48 v system.  There are both advantages and disadvantages to rigging solar in either series or Parallel, but shrinking the solar panel footprint is not one of them.  Shrinking the thickness of the wire from Panel to controller though is an advantage of a series configuration.

https://www.renogy.com/learn-series-and-parallel/


Ehrich Rose
Kahuna    6
Hull 281