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Old 03-03-2011, 08:29   #1
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Solar Enough ?

Plan on cruising from Canada to Caribbean in 2012. \Have 39 foot sailboat with instruments, non-led lighting and lap top, frig runs off engine and shore but might switch to DC. Two people.

Can solar alone (with sufficient panels) provide my electrical needs or do I need to have wind as well? Thoughts?
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Old 03-03-2011, 08:35   #2
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Re: Solar Enough?

mparent,

Solar is all you need. Silence is golden.
Here are a few solar examples.

Solar Panels and Associated Systems

Solar Panels and Associated Systems

Solar Panels and Associated Systems

Mark
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Old 03-03-2011, 08:37   #3
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Re: Solar Enough?

one of the biggest problems I have with my solar is how poorly it performs at night.

seriously, my biggest electrical draw is not at anchor. it's underway at night. and that's when I most appreciate the fact that I also have a wind generator.

dollar for dollar, changing out that non-led lighting is going to help considerably.
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Old 03-03-2011, 09:39   #4
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Re: Solar Enough?

Our boat has been solar self sufficient for the last 15 years and it works great for us! Having had both solar and wind, I found it to be both quiet, and produce more amps, averaged out over a year. We got rid of our wind gen years ago, for this reason... It made room for a 110w panel on the stern.

Solar DOES work fine at night! We have a house battery bank that has an ah capacity which varies between 7 X (at sea), and 10 X (at anchor), THE DAILY a/h CONSUMPTION of the boat. When you run your boat off of the batteries at night, and they are charged by solar in daylight, you ARE running the boat 100% on solar energy, only the night portion, is "STORED solar energy".

On the land as well as in cruising... BY FAR, the best "bang for the buck" is in energy "conservation" rather than energy "production". A super insulated fridge, led (running, anchor, and reading lights), fluorescent cabin lights, balance the sails correctly, to limit autopilot work, etc...

After making the boat as energy efficient as is practical, figure in your daily ah consumption. If you are running your engine every day anyway, do so first light every morning. This is when the batteries are their lowest and can accept the largest amount of the amps being produced by the alternator... (while chilling down the fridge).

Take this consumption #, and you need at LEAST twice this much in solar panels. This keeps you covered on cloudy days, when solar produced amps are reduced by 1/2!

You need a large enough battery bank, to only be about 10% down in the morning, then you should be charged up by noon, or all day if it's cloudy.

IF you spend 95% of your time at anchor, like we do, you can have your system 100% solar, UNTIL you are under way, (which might double ah use). Then run your engine first thing like usual, only for an extra hour... Since this is only a fraction of the time, you would still be 100% solar, 95% of the time.

If space makes this an impractical goal, you could let the engine run in the morning do half the work, and let the solar top them off over the day. No matter the size of the alternator, they are not great for topping off batteries, as their extra amps cannot be absorbed when batteries are near the top.

Bringing them back to 100% every day, will double their lifespan! (It also makes things run better).

If you point your stern panels toward the setting sun on a pivoting rack, you can add a lot more amps, on a cloudy day.

Hope this helps, Mark
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Old 03-03-2011, 10:02   #5
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Re: Solar Enough?

It doesn't make any sense to think about solar until you have switched to DC refrigeration. Running your propulsion engine for a couple of hours each day isn't good for it.

With an efficient refrig system like Frigoboat and good insulation, your refrig should use 50 amphours our so. Add led lights, laptop use, CD or radio and some inverter/microwave use and you probably can keep your daily AH use down to less than 100 amphours.

You will probably need 300 watts of solar to keep up with this in a low lattitude, mostly sunny environment.
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Old 03-03-2011, 10:04   #6
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Re: Solar Enough?

One thing that I might add in agreement with Bash... IF you will be spending over 50% of your time at sea, where a/h consumption remains high, and the wind becomes more reliable, and IF you are limited in space for ENOUGH solar... then wind AND solar make more sense... (As long as the wind unit does NOT shade the solar panel).

Kiss generators are high output, really tough, and far less annoying than the Air Marine, Air X, Air breeze models...

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Old 03-03-2011, 10:23   #7
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Re: Solar Enough?

Quote:
Originally Posted by djmarchand View Post
It doesn't make any sense to think about solar until you have switched to DC refrigeration. Running your propulsion engine for a couple of hours each day isn't good for it.

With an efficient refrig system like Frigoboat and good insulation, your refrig should use 50 amphours our so. Add led lights, laptop use, CD or radio and some inverter/microwave use and you probably can keep your daily AH use down to less than 100 amphours.

You will probably need 300 watts of solar to keep up with this in a low lattitude, mostly sunny environment.
ALL, very good points... We used vacuum panels and built a 2 qu/ft "super efficient" 12v fridge. This is the "big deal" at anchor, so keeps our daily use less than half of the above mentioned 100 ah. (Yes, we use a watermaker, watch movies at night, etc) We just maxed out on the energy conservation thing. This may be why our 285 w of solar has worked so well for us?

On a really good day, we may be charged up by 10:30 or 11:00 AM! It keeps our asses covered for the more marginal conditions.

We still run a slight energy deficit when doing a week at sea, because the computer, VHF, SSB, radar, and autopilot, can double the load. For these days only, we run the engine for 45 minutes, just before sun up.

We're "island hoppers" living on the hook, for the most part, so this isn't very often.

Mark
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Old 03-03-2011, 10:37   #8
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Re: Solar Enough?

I cruised my cat for over four years and for most of that time I didn't even have a shore power cord. It was all solar and engine generator powered.
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Old 03-03-2011, 11:13   #9
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Re: Solar Enough?

I get a lot of power from my two 135 watt panels. Good charge controller and 4 Trojan T105 batteries. Usually only one of the panels is in full sunlight for maybe 2/3 of the day. The only time things don't work so well is when it's dark and cloudy for days on end, which even happens here in Southern California.

We've done a lot to reduce our electrical load:

- Engel fridge. Uses 1-3 amps, fires up for maybe 20-30 minutes every 2-3 hours.
- SensiBulbs for interior lights. We can have all our cabin lights on and we're using ~1 amp.
- LED navigation lights. Again, maybe ~1 amp for all of them.
- Portable plugin inverter. It will run one laptop and charge the phones / kindles.
- Foot pumps in the galley. Save water, save power.
- Manual windlass. Ladies love a man with a strong back.
- Wind indicator is solar powered.
- Turn off instruments you don't need.

The deal with solar is that sometimes you have lots of power, and you'll want to make use of it. Charge up all the devices during the afternoon when there's power to spare. Run the water maker then. Focus on reducing current draw especially when it's dark. As noted above switching out to LED lights (big recommendation for SensiBulbs) allows you to have plenty of light and not run around like a electrical nazi turning off switches all the time.
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Old 03-03-2011, 11:45   #10
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Re: Solar Enough?

You are not likely to have sufficient boat space for the amt of solars that you would need to run everything on DC.

In any case solars work great if installed properly. We get up to 40 Amps per day from a 150W installation on 12 V system. Nothing, if overcast ;-)

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Old 03-03-2011, 12:03   #11
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Re: Solar Enough?

If you keep the engine driven refrigeration, the amount of time you have to run the engine per day will probably keep your batteries charged with no solar or wind, especially if you have a high output alternator, and go to LED lighting.

Unless you change the refigeration, I think you should save your money. Replace the lighting with LEDS. Incandescents are inefficient, and they are hot -- a factor to consider if you're heading south. If you go to DC refrigeration, then put on as many solar panels as you can fit before you spend money on a wind generator.

We're on a 35 foot full-time cruising boat with DC frig, LEDs and 150 watts of solar panels. We have a 400 watt wind generator. In the Caribbean, with the trades blowing through the anchorages, we rarely run the engine to charge the batteries, but for the east coast and the Bahamas, we'd gladly trade the wind generator for another 150 watts of solar panels.
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Old 03-03-2011, 12:07   #12
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Re: Solar Enough?

Quote:
Originally Posted by barnakiel View Post
You are not likely to have sufficient boat space for the amt of solars that you would need to run everything on DC.

In any case solars work great if installed properly. We get up to 40 Amps per day from a 150W installation on 12 V system. Nothing, if overcast ;-)

b.
This last statement just confuses me... I have heard it before.
Is this measured with a smart battery monitor, like a "Link 10" ? Do you have amp meters on each panel, like we do? Do any of them tilt? are they shaded by the rig? I just don't get it.

OUR experience has been that with our 285 w. worth of panels, (spread over 4 locations), we get a max of 60 ah on a "great" day, average about 50 a/h, and if it's a cloudy but very bright "squinty" white sky, we get about the same. When it is quite overcast, we get over 30 ah, and if it's almost SO darkly overcast that you can barely see, we still get about 20ah...


If we tilt the aft panel several times, we get 10 more a/h!

I wonder if our experience is really that different, or are these statements about solar "not working at all on cloudy days", more of an assumption, than verified?

It could be that our panels being so spread out is an advantage, or that my having installed a low v loss "Shotkey Diode" in each panel, makes them more efficient on overcast days? I don't know...

I do know that for us, the difference in a fairly dark overcast day, is that our solar panels might take all day to replace our previous nights 35 a/h deficit, rather than by noon.

Mark
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Old 03-03-2011, 12:56   #13
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Re: Solar Enough?

I have 460 watts of solar panels and make more power than I need.
With the new solar panels that they have today, it's no problem.

I will just have to add more batteries if I see they are not keeping up on our overnight cruises.

Right now I have no problems. Batteries are always fully charged after 9:30 am.
We have LED lights on everything, mast, reading, heads, gages.
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Old 03-03-2011, 15:29   #14
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Re: Solar Enough?

Mark:

You must be in a high lattitude location. My experience is that 100 watts of solar panels will put out 33 amphours of 12V DC on a full sun day with a flat panel in the summer at moderate lattitudes.

Medum density overcast drops the output to 1/5 or less. It may be that your diodes improve your low light performance if the low light intensity results in a low enough voltage. The lower voltage drop of the Shottkie's will help this.
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Old 03-03-2011, 15:59   #15
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Re: Solar Enough?

Today’s solar panels are truly magical. They pump out the power and are quiet and maintenance free.
After the first week we forgot they are even there.
My 12 volt fridge/freezer is left on and on high for the whole season.
We leave our LED lights on just like we are at home.

This is by far the best upgrade you can do to any boat.

We do not miss putting the Honda 2000e generator on the stern twice a day for an hour. It’s a drag.
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