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Old 26-01-2014, 21:05   #1
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Panel size.

I was hoping someone could give me the correct size requirements for solar on my 40ft yacht.
My power requirements are
Fridge freeze
Plotter
Ais
Gas monitor
Vhf
Hf
Instruments
Radio
Auto helm ??
Total 11 amps per hour

I have 3*80amp hour batteries totalling 240 amp hours.
Thanks
Jeff

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Old 26-01-2014, 21:15   #2
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Re: Panel size.

Sounds like you may want to add some total amp hours to your battery bank to start. I am looking to build a system for a 40 ft. sailboat as well and am currently researching different solar panels. Right now I'm aiming for around 3-4 140W panels.
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Old 26-01-2014, 22:06   #3
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Re: Panel size.

We've had all the things you list plus a big water maker and four 125 amp Kyocera panels and 625 amp hours of battery capacity since June 2000.

In Western Mexico 18 degrees North to 29 degrees North - summer and winter

1000 nights at anchor

The batteries were always fully recharged by 2 PM and we could run the water maker, refrigerator compressor, and still trickle charge the batteries for a couple hours in the afternoon.

The answer to question really depends on where you are (latitude and sky cover).

You can read more at: SOLAR PANELS and ARCH
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Old 26-01-2014, 22:41   #4
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Re: Panel size.

Jeff it depends on lot of factors.
The biggest is the effency of the high power users especially the fridge / freezer
The other side of coin is where and when and how you will be using the yacht.
Sydney has quite good insolation in summer, but not great in winter (do you want to use the yacht year around). Will there be other sources of power especially shore power?

If you want a proper answer you need to measure your typical power consumption (in AHrs) The easiest way is use a battery monitor which is almost an essential anyway.

For a rough starting point 300w in summer and 600w for winter, but these numbers could be out by a factor of 2, or more.

Without more involved measurements a common technique is to fit the largest solar array you can reasonably fit and hope it is enough. Solar panels are cheap and this is not a bad philosophy, but it can lead to disappointment if the panels do not supply sufficient power, or frustration where more money spent on high efficiency panels might have made the system self sufficient.
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Old 26-01-2014, 23:57   #5
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Re: Panel size.

The figures above do represent amp hours which where derived from checking the specs on the items themselves. I suppose I am looking for the calculation for that load. To maintain the battery bank. I can add one more battery if needed.
I also run a D400 wind gen. Which can keep up with things if its blowing 15+

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Old 27-01-2014, 00:12   #6
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Re: Panel size.

Remember that while you feel your total load is 11 amps per hour that is not the way it works as you use each item at different times. For example your fridge might draw 6 amps per hour when its running but how long does it actually run every hour. If its super efficient and not too big it might only run 10 minutes per hour which is 10 minutes x 24 hours which is 240 minutes divided by 60 which comes to 4 hours x 6 amps equals 24 amp hours per day. You have to take each item and work out the total amp hours needed to start deciding on battery banks and solar needs.
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Old 27-01-2014, 00:41   #7
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Re: Panel size.

Regarding the type of use the boat gets.
For now its mainly a few days at a time every 2 weeks. year round and in Sydney and coastal NSW. The amp hours I am quoting are more for when I go off shore later this year. I want to equip the boat adequately so that the beer stays cold the auto pilot can steer the boat and have the AIS and radios running as required. In short If I need to add the extra battery, I will add it and I have atleast 1.500m* 1.000m of mounting room above my rear davits, so want to add the panels here. I was hoping to have 3 panels running in parrallel which would need to overhang my existing frame.
You will see that I have 60 watts of solar allready. They trickle charge the start batt when I am away. I will be removing them. Heres a pic.
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Old 27-01-2014, 01:08   #8
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Re: Panel size.

Really short answer is that most 40 foot cruisers will use 100-200 amp hours per 24 hours. If you have a real efficient fridge (biggest user) and you have LED lights everywhere and don't sit on the computer all day you might get away with a little over 100 amp hours a day while at anchor. If you had a battery bank of 400 amp hours and around 400 watts of solar and a good controller you would probably be good to go while at anchor. When doing passages you are going to be running radar/autopilot/nav lights/GPS etc. and your loads will go up. You might have to run your engine for an hour every day/second day depending on the sun. Good to have a good hi output alternator (100+ amps) and 3 step regulator. These are all real rough guesses based on my own experience and your needs will be different but its something to think about.
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Old 27-01-2014, 01:11   #9
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Re: Panel size.

By the way that boat of yours has very sweet lines for a centre cockpit, very pretty!
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Old 27-01-2014, 01:50   #10
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Re: Panel size.

jeff -- everyone has answers above but a lot of what you need may well depend on where you are going and how long you plan on being out - answer that and maybe some better answers

before i make any suggestion it makes sense on how the boat is going to be used
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Old 27-01-2014, 02:07   #11
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Re: Panel size.

Thanks for the kind words Robert.
Chuck. I tried to summarize the boats use in the previous post with the picture. I can probably add to that by saying, we want to go to Lord Howe, QLD and maybe Fiji. So in short we want to cruise and live aboard for a while Starting towards the end of this year. Hope that helps.

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Old 27-01-2014, 03:10   #12
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Re: Panel size.

i can only tell you what works or doesn't for us -- we sail a jeanneau ds40 and have been out over 6 years - we also have all the toys

- we have 6 6volt golf cart batteries - t105 - and right now 3 130w solar panels with a 3240 blue sky controller -
we started with 2 panels and found that was not enough - we put on a third but still had to on occassion run the engine - especially when we got a good internet signal and spent way to much on the computer and the net -
we will add a fourth as we have room for it
a picture of our mounting with the 2 panels is in our profile pictures if that helps -
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Old 27-01-2014, 03:31   #13
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Re: Panel size.

The only picture in this thread I am able to see is the one with the profile of the boat in post number 7. All other mentions of photos being attached is not accompanied by an attached photo.
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Old 27-01-2014, 03:45   #14
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Re: Panel size.

Quote:
Originally Posted by Caracal View Post
The only picture in this thread I am able to see is the one with the profile of the boat in post number 7. All other mentions of photos being attached is not accompanied by an attached photo.

the pics are in my profile
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Old 27-01-2014, 04:47   #15
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Re: Panel size.

Quote:
Originally Posted by Hoohaa View Post
Thanks for the kind words Robert.
Chuck. I tried to summarize the boats use in the previous post with the picture. I can probably add to that by saying, we want to go to Lord Howe, QLD and maybe Fiji. So in short we want to cruise and live aboard for a while Starting towards the end of this year. Hope that helps.

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Hi Hoohaa, notice that you are planning to go to LHI. I will be heading that way end of February next year if you want some company. Went out there year before last and had a great trip.

Steve
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