Wind vs. Solar? Recommendations?

[shadow]

I'm from the old school of redundancy. If you can afford the space and money, I'd get both.... Again, every person has their own unique needs and requirements.. Good luck though regardless!!

[MichaelC]

Hey, NatKat. Thanks for starting this thread. And thanks to everyone for the neat, concise answers.

[NatKat]

Thank you for the recommendations and advice!
Leaning toward starting w/ solar and adding wind due to local climate conditions (as posters mentioned June gloom + lots of wind in VTA).
General shout out & thankyou to CF community.
Cheers from Ventura, CA

[S/V Alchemy]

Both, plus a Honda 2000 for brief jobs requiring power tools that aren't worth using the inverter.

I am of the school where avoidance of using the engine to turn alternators (other than when actually motoring) is the goal, along with a preference to avoid a built-in genset.

Key to this is sufficient battery capacity to "make hay (amps) while the sun shines". This is not possible or desirable for some boats due to size or weight considerations, but it's my plan.

[teejayevans]

186 Watts of Solar, will give me ~60AH/day, I use about 45, so extra allows for some cloudy days.
Provides 98% of my power requirements, Honda 1000 handles the rest, I plug it directly into my shore power outlet.
First question to answer is how much do you need?
Tom

[aquarian]

Originally Posted by daddle

Solar only. Quiet. Reliable. When it gets cloudy and dark the refrigerator draws less so it all works out. Besides, if it's not sunny enough untie the docklines and sail to where it is.

Since I have no generator, or even an alternator right now, It's all solar here. Refrigeration, anchor windlass, starting, autopilot, computer, fans, SSB, everything.

Nice places to anchor don't have enough wind. Proper comfortable downwind crossings don't have enough apparent wind. That's my opinion anyway.

Love your perspective!

[gmowbray]

Hi - I guess I am starting up an old thread but the issue is still out there.

I am re-doing my electrical system - and have been assessing Solar only or Wind and Solar. The boat is in the Caribbean so sun is not an issue.

When I am on the boat - I want to use a lot of power .... 2 fridges etc. I don't really want to be power constrained - on the other hand, for 75-80 percent of the year I will be in Canada and the boat in the Carrib - so a mouse in a wheel could keep the batteries up.

My best guess is that I will use 225 Ah per day when on board. That then should translate to a house battery bank of 450 Ah (or 500+ if I allow for 80% charge).

My assumptions are: 9 hour charging window, 5.5 Amps/100 Watt of solar and that leads to about 450Watts of panels. That is a lot of real estate (I have an arch though).

If I flip it around and assume that a wind generator would give me (again assumption) 3 A for 24 hours then I am roughly in the 3 X 100 Watt panels area and that is quite doable.

In reading through the previous discussion, although there is some good stuff there - there are not a lot of real world consumption numbers plus little or no discussion about batteries. It seems to me that the batteries are the heart and soul of an "off-grid" boat.

So - these days what is the thinking? Solar + Wind? Has Wind got quieter? Are there smaller panels than the sort of common 2' by 5' 100 Watt panels.

?

Thanks for all your ideas and help.

[Copacabana]

I think the "9 hour charging window" might be a little optimistic. Normally you can count on 5 hours a day at rated output.

[Pizzazz]

My view is that wind is noisy, especially at night when you sleep but you do get adjusted to the noise and vibration. Solar is great but for backup only. On a 30-35 ft boat you can put 100-200W of panels that will give you 50 AHrs if you are lucky.

I estimate over 200 Ahrs daily consumption (computers, tablets, water maker, washing machine, electric pressure cooker, radar, etc.) for a good life, obviously one can get buy with less if need be. Therefore, for me the only viable option is the engine alternator that also gives you hot water. Solar is only there as a backup to power VHF radio, autopilot and instruments if the engine fails.

[wingssail]

Our power usage is roughly 125-150 or more amp/hours per day (include refer, lights, computer, etc). More when on overnight passages due to instruments, etc. The usage is less when in cold water areas (less refer cycles).

We have 270 watts solar, (tiltable) which gives us up to 70 AH per day, if the wind and sun cooperate to keep the shadows of the mast and awning off the solar panels (mounted on aft railings). We have 420amp house battery capacity.

The difference between usage and solar generation is 60-80 AH per day and we get that running the engine (horrors) with a large capacity alternator.

Since we have an engine already there is no extra cost to this except diesel fuel and wear and tear on the engine. In 27+ years we have not encountered any wear and tear problem on the engine. We have spent over $2000 on alternators and regulators in 27 years but just counting the diesel fuel it works out to be less than $.02 per amp/hr. The alternator and regulator cost amortizes to something like $.005 per AH.

An onboard genset was out of the question due to weight, cost, and complexity of the electrical, cooling, and exhaust connections. We do have a place to put it but didn't want several hundred lbs in the stern of the boat.

Wind generators did not appeal to us due to low output, noise, mounting, etc. Plus, shade on the solar panels would be a problem.

This solution has worked for us. It is simple, light weight, cost effective, and reliable. Our objective was to have a simple system with fewer devices, weight, and complexity.

[Adelie]

Originally Posted by gmowbray

Hi - I guess I am starting up an old thread but the issue is still out there.

I am re-doing my electrical system - and have been assessing Solar only or Wind and Solar. The boat is in the Caribbean so sun is not an issue.

When I am on the boat - I want to use a lot of power .... 2 fridges etc. I don't really want to be power constrained - on the other hand, for 75-80 percent of the year I will be in Canada and the boat in the Carrib - so a mouse in a wheel could keep the batteries up.

My best guess is that I will use 225 Ah per day when on board. That then should translate to a house battery bank of 450 Ah (or 500+ if I allow for 80% charge).

My assumptions are: 9 hour charging window, 5.5 Amps/100 Watt of solar and that leads to about 450Watts of panels. That is a lot of real estate (I have an arch though).

If I flip it around and assume that a wind generator would give me (again assumption) 3 A for 24 hours then I am roughly in the 3 X 100 Watt panels area and that is quite doable.

In reading through the previous discussion, although there is some good stuff there - there are not a lot of real world consumption numbers plus little or no discussion about batteries. It seems to me that the batteries are the heart and soul of an "off-grid" boat.

So - these days what is the thinking? Solar + Wind? Has Wind got quieter? Are there smaller panels than the sort of common 2' by 5' 100 Watt panels.

?

Thanks for all your ideas and help.

I would say you want 3x daily use for battery capacity. So if you are using 225a-hr/d you want 675 amp-hr battery capacity.

Rule of thumb for solar output used to be 25% of nameplate capacity in watts equals daily output in amp-hr. With a separate MPPT controller for each panel it's more like 33%. Try to use one big controller and it's going to be under 30%, shading on 1 panel will drag them all down.

Let's say you want 250 a-hr/d, that's 750w solar.
I have a Cal 20 and I can fit 175 on an arch, plus another 200 over the cockpit as a bimini. I bet you can break 500w just in those 2 locations on your boat. Remember to orient the bimini panels so there is one on each side of the boat centerline. If you are close hauled and one side of the bimini is shaded you don't want half of both panels shaded, then you get nothing out of either panel, you want one panel on one side shaded and get the full power out of the other panel.

With the fridges you want to turn down their thermostats to just above freezing in the PM, say 1300 or so, when the panels are putting out more power than the batteries can absorb. As soon as power starts tapering off in the evening bump the thermostat back up to 44F or so. Add insulation if you can, even if it is not on all sides.

If you are running a freezer turn it way down in the afternoon and reset to 28-30F in the evening. If there is any free space in the freezer, fill it with water bottles to add thermal inertia to the system. Maybe even freeze water in the afternoon, then transfer the frozen bottles to the fridge in the evening.

[thinwater]

I lean towards solar because of the noise of wind. I'd max out on solar area first... which on multihulls is normally enough!


But I'm sure it is a regional thing.

[Adelie]

Yeah, I forgot to mention wind. There are certain places where solar won't be enough and wind will work, The Med during certain seasons comes to mind, but I don't remember what time of year.

For the Caribbean solar will cover everything pretty much year round. During things like named storms, it won't be enough, but you and the boat shouldn't be there for hurricane season.

There are a few very quiet wind machines, otherwise you run a serious risk of annoying your neighbors, in the marina or at anchor.

[Mike OReilly]

Originally Posted by gmowbray

So - these days what is the thinking? Solar + Wind? Has Wind got quieter? Are there smaller panels than the sort of common 2' by 5' 100 Watt panels.

Yes, wind has gotten a lot quieter. These days there is no reason to put up with a noisy air- type of screamin' banshee wind gen. There are lots of good, and fairly quiet, ones to choose from.

I carry both, and sail exclusively (so far) in mid-higher latitudes (~49 N - Canada). I’ve never accurately measured this, but I think my 400 watts of solar accounts for about 85% of our amp needs, with wind doing the rest. But this is highly variable from day to day, and often when solar is languishing, wind is excelling. So having both works well for us.

BUT… I would definitely maximize solar first. If your charging needs can’t be met with solar, then look at a wing gen. But for g-d sake, don’t get one of the noisy ones.

[gmowbray]

Thanks guys - this is all good stuff.