If you’re planning to be away from the dock for more than a day or two – and won’t be motoring every day – the big question is how you’re going to supply your power needs.
After you’ve brought down your power consumption as much as is reasonable (note that I say “as much as reasonable, not “as much as possible” since it’s up to you to decided what’s acceptable and what is not), you have to figure out how you’ll supply the power. There are three widely used options: solar panels, wind turbines, and gas or diesel generators. This is a high-level overview comparing the three.
Solar is the workhorse for cruising boats. In most locations, solar will provide the most power per dollar spent and thus most boats first try to maximize their solar output.
Not all solar panels are created equal: there is a vast difference in quality and the more efficient panels do cost more (but don’t assume that a more expensive panel is necessarily more efficient). Your charge controller will play a big role in how much your system provides to the batteries, and of course your battery bank must be large enough to accept all the power your panels put out.
In general, the best panels are over 20% efficient, and experts generally recommend 1 to 2 watts of solar per amp-hour in your battery bank (I tend towards 2 watts in general and would even go for 3 if you typically have cloudy weather).
High voltage panels (30 to 50+ volts) are more efficient, particularly when paired with high quality MPPT charge controllers – one per panel. We’ve had extremely good results with the Victron MPPT charge controllers but there are other good brands as well.
There is very little maintenance with solar panels (wipe any dirt off) and rarely any need for repairs.
The cons? First is the space available on your boat to mount panels. Second is shading by things like the mast, shrouds, radar dome and pole, and whatever else. Any amount of shading decreases production out of proportion to the amount of the panel that is shaded. Third is cloudy or rainy weather. Fourth is that they don’t produce well in the winter, due both to shorter days and the fact that the sun is lower on the horizon. Finally, improperly mounted panels can produce enough heat to cause a fire.
A fair number of cruisers opt for wind turbines as a supplement to their solar panels. The good part is that they produce 24 hours a day and often produce the most on days that are poor for solar. Wind turbines, however, generally cost more per watt generated over their life.
Each system has its own best wind range, so you need to do some research on typical wind speeds for the area you plan to cruise. The same unit is not going to be popular in both the light air of the Sea of Cortez and the trade winds of the Caribbean.
Wind turbines tend to have more maintenance and repair than solar panels, but it is usually within the abilities of a DIY cruiser. Finding parts can be an issue at times.
Another important consideration is the noise produced by the unit. Quality installation – whether by a top-notch professional or meticulous attention by a DIY-er – is key to low noise levels, but some models are inherently noisier than others. Don’t just rely on manufacturer’s specs; go around to boats, listen and talk to owners. Often turbines don’t seem so loud from the dock or dinghy but become much louder down below in the boat as noise is transferred down a mounting pole. This is especially an issue if someone is trying to sleep right below the mounting pole.
Finally, the spinning blades are a safety concern; a wind turbine must be mounted where no one will possibly be hit by a blade.
Gas or Diesel Generators
Running your boat’s primary engine just to charge the batteries is very hard on it. Consequently, people turn to gas or diesel generators for times when solar or wind power just isn’t enough.
Typically, portable generators (often Hondas) are gas powered while permanently-mounted ones are diesel.
The major pro of a generator is that you can have power whenever you need it, although you generally shouldn’t use a portable generator in the rain.
Cons are the use of fossil fuel (and its cost), the need to source and store additional fuel, the maintenance and repairs, finding parts, the noise, and the exhaust. There are also safety concerns from the fuel storage, carbon monoxide, and even (very rarely) fire.
Many cruisers rely on all three of these options to meet their power needs no matter what conditions they face. But only you can know exactly which option or combination will work best for you.
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