Solar power systems

[WayneH]

I guess I should mention that the house in Texas is completely off-grid. Rainwater collection and 7.2KW of solar on the roof. The one incoming utility is high speed internet. A couple of years ago, we built a deck to provide the water tanks with protection from the sun and while doing that added a wind turbine above the deck at a distance of 20 feet higher than the deck. The wind turbine output is dismal to the point that I call the turbine a community relations device as it appears we are doing our best to keep the generator from running. Most days, the turbine generates 0.1KWH of electricity while the panels do that almost before the sun comes up.

 

[pgandw]

Just think about it - how much sail area do you have to spread to get the push of a 3hp outboard engine (1,000 watt equivalent) with all its engine and prop inefficiency? Or a larger boat with 8hp diesel? Do you really think a fan of any reasonable size to mount on a boat is going to generate significant amounts of power?

Fred W
Stuart Mariner 19 #41333 Sweet P
Yeopim Creek, Albemarle Sound, NC

 

[dlochner]

John Harries on Attainable Adventure Cruising on how to make a fast boat go slow for cruising (note the article is behind a paywall, his site is well worth the money if you are into cruising or want unvarnished options on boats and systems). High on the list was adding a wind generator. Long ago before solar was affordable and doable, wind was only one of the options.

 

[dLj]

John Harries on Attainable Adventure Cruising on how to make a fast boat go slow for cruising (note the article is behind a paywall, his site is well worth the money if you are into cruising or want unvarnished options on boats and systems). High on the list was adding a wind generator. Long ago before solar was affordable and doable, wind was only one of the options.

I subscribe to John Harries web page - I can't state more strongly that it is a FANTASITC resource!

It took me a minute to find the info from the above reference from @dlochner , but here's the conclusion on wind generators:

"This will be controversial but, in my view, given the existence of the Watt & Sea and more efficient solar panels, wind generators, even though they have long been the standard solution for self-sufficient sailors, are no longer a good solution for most of us."

His entire article is called:
Replacing Diesel-Generated Electricity With Renewables, Part 1—Loads and Options


Subscribe and read the whole article. It's excellently written, as pretty much everything on that website is.

dj

 

[American_Mainsail]

Just think about it - how much sail area do you have to spread to get the push of a 3hp outboard engine (1,000 watt equivalent) with all its engine and prop inefficiency? Or a larger boat with 8hp diesel? Do you really think a fan of any reasonable size to mount on a boat is going to generate significant amounts of power?

Fred W
Stuart Mariner 19 #41333 Sweet P
Yeopim Creek, Albemarle Sound, NC

Your point is well taken here, Fred.

Here's a wind energy calculator that's pretty cool. I played around with it by putting in the specs of a Primus Air Silent X turbine into it (24" blades). I determined the efficiency by picking efficiency numbers that produced results that match their output curve. The efficiency ended up being between 25-30%, which is reasonable based on sources I found.
Wind Turbine Calculator [HAWT and VAWT]

The long story short, for me, is that siting is everything with these. If you have a specific use case in mind with the boat at a specific location where there is a strong prevailing (or local) wind then they can start to make sense, theoretically. Other than that, they're going to put out maybe one or two amps (12V) most hours of the day.

 

[dlochner]

For those who don't know John Harries, he is a life long sailor who has done a lot of high latitude sailing. Recently he sold his McCurdy and Rhodes aluminum expedition boat and purchased a J 109 for cruising. The actual title to the article is 12 Tips to Avoid Ruining Our Easily Driven Sailboat. In this article omitting a wind generator was based on 3 concerns, excess windage, weight in the aft end, and very limited efficiency.

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