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Old 19-12-2012, 23:19   #1
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Solar Panel Mounting on Bimini

Originally Posted by noelex 77
It looks to me like you have plenty of room for a reasonably easy solar instalation. All boats get some shading, yours is a bit more than most, but you have a large area and solar is very cheap these days, more panels will make up for shading, some will always be producing and even those in shade will provide some contribution.


On another thread about PMA and maximizing DC Generation for my motor sailor, Nolex 77 advised that I review a Solar strategy for my large Bimini area.

Disclosure…I have Zero experience with Solar panels!

Problem is I keep reading conflicting reports about shading effects from both Users and warnings from Suppliers, so I have been hesitant to make such a large financial commitment.

All my DC consumers are 24v and I have 8 x 260AH Fullriver AGM’s storing 1040AH @24v

New Bimini Support was very strongly built for a Hard Top, but the contractor really overbuilt the hardtop so I replaced with a lightweight Stamoid vinyl cover.

In Sketch…Black Solar Area I chose is behind my standing rigging (Green Dots) and away from centered aft Boom with a total Area of at least 7 sqm

I would appreciate real world advice from anyone who has installed Solar to look at my Bimini situation and advise if they would install Solar Panels in the Area I marked on Sketch.

Questions: Based on living in the Tropics
  1. For a 24v DC House Bank, what type of Solar Panels should I consider to maximize output given mast shading loss and high Temp?
  2. What make would you recommend?
  3. What percentage of shading loss should I expect when at anchor?
  4. Wiring Tricks to keep from losing output from shaded panels
  5. What 24vdc output via best controllers can one expect for a given rating?
  6. What minimum space between Vinyl Bimini and Solar Panels, should I maintain for cooling?
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Old 19-12-2012, 23:29   #2
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My opinion is that some posters exaggerate the shading problem. My rigging makes shadows on the panels at times. They still make reasonable power. At anchor the boat is always moving, so there is no perfect solution. More solar the better.
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Old 20-12-2012, 01:33   #3
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Re: Solar Panel Mounting on Bimini

Fit the solar panels in the black area shown on your plan. Avoid the the central area where the boom shadow will be.
You should be able to fit about 1000w which should make a a very worthwhile contribution to energy budget.

Given slightly more shading than normal I would expect about 170AHrs @ 24v in conditions of very good insolation such as the sub tropics in summer. About 110AHrs @ 24v in average conditions. A very bad day say overcast in winter might only give 40AHrs per day.

You can fit almost any panels you want, but the wiring will be slightly different. The best choice would be some of the high voltage panels. Panels with 72, or more, cells ( the individual squares of silicone) will be best
The controller will step this down to 24v so 60v or more is fine.
Some panels are called 24v panels but only have 60 cells and these are ironically not ideal for your 24v system. Nominal 12v panels ( with 36 cells)can be used by wiring them in series (to give an effective panel with 72 cells) but an even number of panels is necessary.

High efficiency panels will allow you fit more watts in the available space, but will be dearer.
Local availability and cost will major deciding factors ( freight can be dear on the larger panels). Rigid panels are much cheaper and you don't need flexible panels.
Keep all the panels the same and fill the black area with whatever number and size of panels are easiest to mechanically mount. Say 2x 250w or 3x 140 w panels on each side.
If you can arrange them so the panels are length wise it will be slightly better than width wise.

With a large system like this you will need an expensive controller something like an outback 60 will be needed so add that to into the cost.
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Old 20-12-2012, 02:53   #4
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Re: Solar Panel Mounting on Bimini

Thanks, I will read up on past Solar posts and try to gleam some consensus on details.

How much heat will the panels radiate down on Bimini??

Final solution positions will depend on how much air circulation is needed in combination with sail up boom clearance and Bimini camber.
I will measure that clearance tomorrow
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Old 20-12-2012, 03:49   #5
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Try this option perfect for bimini tops, you can put on with zippers so they can be removed

http://www.solarfuture.com.au/
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Old 20-12-2012, 06:43   #6
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Re: Solar Panel Mounting on Bimini

Quote:
Originally Posted by noelex 77 View Post
If you can arrange them so the panels are length wise it will be slightly better than width wise.
Why is that??
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Old 20-12-2012, 06:54   #7
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Re: Solar Panel Mounting on Bimini

Quote:
Originally Posted by Pelagic View Post
Thanks, I will read up on past Solar posts and try to gleam some consensus on details.

How much heat will the panels radiate down on Bimini??

Final solution positions will depend on how much air circulation is needed in combination with sail up boom clearance and Bimini camber.
I will measure that clearance tomorrow
Pelagic:

I have my panels directly located on the old dodger frame and a new bimini frame extension which I installed
THE BIANKA LOG BLOG: SOLAR BIMINI PART SEVEN: PANELS INSTALLED
and have not noticed any heat radiating down into the cockpit. The bottom of the panels are warm but, not hot.
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Old 20-12-2012, 07:34   #8
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Re: Solar Panel Mounting on Bimini

Quote:
Originally Posted by Pelagic View Post
Why is that??
You will get a higher output if some of the panels are shadow free.

So if you have say 4 panels a lot of shadowing on one panel with little shadowing on the other three will give a higher output than a moderate amount of shadowing more evenly distributed over all the panels.

If the panels a laid with the long axis along the beam the shadow of the boom, which will be the largest densest shadow will fall significantly on all the panels on that side.
If you lay the panels with the long axis fore and aft the boom shadow will probably only fall on one panel. The outboard panel will have no boom shadow.

50 % shadowing on 2 panels will give much less output the 100% shadow on one panel, but full sun on the other.

These are simplistic examples, the real situation will be dynamic with multiple smaller shadows from the rigging wires etc, but they illustrate the point.
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Old 20-12-2012, 07:56   #9
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Re: Solar Panel Mounting on Bimini

Quote:
Originally Posted by mbianka View Post
Pelagic:
I have my panels directly located on the old dodger frame and a new bimini frame extension which I installed and have not noticed any heat radiating down into the cockpit. The bottom of the panels are warm but, not hot.
Thanks mbianka… if I understand correctly from your blog, you removed the canvas and replaced with solar panels…. So full circulation underneath??

I was hoping to be able to leave the Stamoid Vinyl Bimini in place for rain protection and just install short attachment risers for the Solar panel framework. This would leave about one inch air space between the Solar panels and Vinyl.
My concern is that the panels need more circulation on the underside.

Alternatively, if that is not enough space, I can look at removing the vinyl and fashion a waterproof solution to mount panels on a modified Bimini frame…. (but I believe that would be much harder to do)
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Old 20-12-2012, 11:25   #10
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Re: Solar Panel Mounting on Bimini

Pelagic,
1) First just some generic info that you should find helpful....then some more specific recommendations later....


2) Depending on "where" and "how" you are sailing/cruising, the advice / recommendations will vary....
But, for "most" cruising in the tropics or temperate latitudes, between 30* N and 30* S (as well as summertime up thru 40* latitude), adding as much UNSHADED solar as you can fit, before wind-gen or water-gen is my usual advice as well as most of us who've done so!!!


In cases where there will be shade on the panels, it is best to figure daily energy output conservatively, and make calculations based oin the total amount of solar (in watts) that will be unshaded for most of the day's highest production hours (+/- 3 hours from local noon).....


Note that depending on your exact layout and what shading you have, this number may be taken from panels in one central group....or different panels (such as some on one side working well before noon and others on the other side of the vessel working well after noon)
{as an example, if you had 600 watts total, and in the moring you had 200 watts on one side shaded, and in the afternoon had 200 watts on the other side of the vessel shaded....you should figure daily average energy generation form the array based on approx 400 watts....and whatever extra output you get is just an added luxury...}



As for calculating that energy generation for planning purposes....
Depending on "where" and "when" you're sailing/cruising, the values do change....but for the most popular areas within 30* of the equator, you can calculate a daily average over an entire years...(having higher production in summertime with higher sun angles and lower production in witer with lower sun angles)


Based on your 24 volt system, and using MPPT controllers, you can take the total amount of unshaded solar (in watts) X 20% = average daily A/H's generated by the solar array....
{Using the above example of a 600 watt array, with an average of 400 watts unshaded for the highest producing hours, that gives you 400 x 20% = 80 amp / hours generated per day.....


{You may wish to take note that for many years the "rukle-of-thumb" for "year-round" solar array daily A/H average outputs (into a 12vdc system), in SE USA, Caribbean, etc. (or other areas with decent sunshine and sun angles) was 33% of the total wattage of unshaded panels.....and since MMPT controllers and some increases in panel efficiencies, this is now usually about 40% (or more).....
And, I've just reduced those amps (A/H's) by half, based on your 24-volt system....}

Have a look at an article/photos of my solar set-up here....
http://www.c470.jerodisys.com/470pix/47004.htm


I hope this brief posting helps...more later...

John
s/v Annie Lauire
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Old 20-12-2012, 12:10   #11
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Re: Solar Panel Mounting on Bimini

Pelagic,
Bottom line: The more solar the better!!!!
Install as much unshaded as you can fit/afford, and you will NEVER regret it...and will wonder how you lived without it!!!


1) I'm a bit handicaped by using "English units" rather than metric....so give me a little slack....


2) What Nolex wrote is great...
But, I'm a bit unclear if you'd be placing panels on both sides of the bimini or just in the black area on one side???
If just in the one black area, then I disagree on this point....

And, since the boom will be in any/all positions undersail (and can be pulled outboard and secured away from the panels when at anchor), you might need to consider exactly where the boom will be "most of the time"....also taking into account adequate air flow UNDER the panels to keep them cool in the hot tropical sun (they DO get hot!!!), before deciding on exactly where to place the panels....

I agree 100% with his other points about panel shading and placement, etc. and especially his point about your actual shading situation being "dynamic" (as I wrote in the paragraph above).....


3) Yes, you are on the right track here....
Quote:
Originally Posted by Pelagic View Post
Final solution positions will depend on how much air circulation is needed in combination with sail up boom clearance and Bimini camber.
My usual recommendation is to allow at least 6" (15cm) of clearence betwen the panels and the surface below them....the more the better....

But, no worries on the panels radiating heat down onto the bimini / into the cockpit.....the opposite is usually true, the bimini cloth (Red Sunbrella on my current bimini) under the solar array is cooler than the dodger cloth (same Red Sunbrella) with no panels above it!!!

Solar Panels



4) "Shading" is different from "shadowing"....
a) I get shadows from my backstay, etc. and this has little effect on energy production.....and even if it did, my mast would stay up for long if I removed the rigging....

b) I can get shading (on certain points of sail) from the mainsail when the sun is low in the sky, and that DOES have a large negative effect on energy production....

So, for clarification....
A shadow from a backstay, shroud, etc. is usually not a problem / isn't something to worry about.....
But shading from the boom 6" above the panel is a problem and IS something to consider....

BTW, 30 years ago when I started using solar-power in remote off-grid locales I never had any issues with shading (never knew it was such an important issue)....and it wssn't until 15-20 years ago when I was doing solar on boats did I find that shading WAS an issue....as is adequate air flow around and under the panels!!!



I do hope this helps....

Fair winds and sunny skies...

John
s/v Annie Laurie
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Old 20-12-2012, 12:36   #12
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Re: Solar Panel Mounting on Bimini

Quote:
Originally Posted by ka4wja View Post
Pelagic,
Bottom line: The more solar the better!!!!
Install as much unshaded as you can fit/afford, and you will NEVER regret it...and will wonder how you lived without it!!!


1) I'm a bit handicaped by using "English units" rather than metric....so give me a little slack....


2) What Nolex wrote is great...
But, I'm a bit unclear if you'd be placing panels on both sides of the bimini or just in the black area on one side???
If just in the one black area, then I disagree on this point....
Yes I agree put the panels on both sides.

Quote:
Originally Posted by ka4wja View Post
Pelagic,
Bottom line: The more solar the better!!!!
Install as much unshaded as you can fit/afford, and you will NEVER regret it...and will wonder how you lived without it!!!
+1

More solar is better. solar has got cheap enough that if the panels are in a sub optimal position, or orientation installing a larger array will make up for the deficiency.

Quote:
Originally Posted by ka4wja View Post
Pelagic,
Bottom line: The more solar the better!!!!
Install as much unshaded as you can fit/afford, and you will NEVER regret it...and will wonder how you lived without it!!!


1) I'm a bit handicaped by using "English units" rather than metric....so give me a little slack....


2) What Nolex wrote is great...
But, I'm a bit unclear if you'd be placing panels on both sides of the bimini or just in the black area on one side???
If just in the one black area, then I disagree on this point....

And, since the boom will be in any/all positions undersail (and can be pulled outboard and secured away from the panels when at anchor), you might need to consider exactly where the boom will be "most of the time"....also taking into account adequate air flow UNDER the panels to keep them cool in the hot tropical sun (they DO get hot!!!), before deciding on exactly where to place the panels....

I agree 100% with his other points about panel shading and placement, etc. and especially his point about your actual shading situation being "dynamic" (as I wrote in the paragraph above).....


3) Yes, you are on the right track here....
My usual recommendation is to allow at least 6" (15cm) of clearence betwen the panels and the surface below them....the more the better....
Keeping the panels cool helps a lot, 6 inches clearance is great, but difficult to achieve in practice. Boats have the advantage of a reasonably strong airflow and and half inch or so is fine. Many panels are attached, or even glued to the deck, while this not ideal it still works.
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Old 20-12-2012, 17:34   #13
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Re: Solar Panel Mounting on Bimini

Lots of good info. I'd add one thing. If I felt one side or the other was going to get significant shading I'd run two MPPT controllers. That way the panels in the sun would not be effected by the shaded ones. A Blue Sky tech recommended that when I was helping a friend with his system. One for one side and one for the other.

If you get over 500 watts you might need two controllers and or they might not be much more expensive than one large one.

If I was running 2 controllers and they were the Blue Sky I would also get their IPN-Pro remote...

Blue Sky IPNPRO Remote Display with 25' Cable

It would really optimize the whole system. We run their MPPT controllers on both boats and like them. We only have minor shading issues on our arrays so only run one controller per array.

More on our arrays...



here....

Endeavour 37 Electrical Mods Index

.... and here....

Macgregor 26S Outside Mods page 33

Good luck,

Sum
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Old 20-12-2012, 18:50   #14
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Re: Solar Panel Mounting on Bimini

Thanks all for your real world input and numbers!
So far I have gone thru about 50 solar websites and am at page 22 of 132 on CF Solar/multiple Controller decisions and proud to say I have not resorted to strong drink!!

Design Parameters…
  • Will put Panels on both sides (I just showed one side for clarity)
  • Estimate minimum 7sqm total, but that will depend on config.
  • Changed Mizzen sheets to traveler bar on davits (by elbow) so can extend solar further aft
  • Always in the tropics between 0 to 14° so heat issues are high
Cooling panels:
Ka4wja:… My usual recommendation is to allow at least 6" (15cm) of clearence betwen the panels and the surface below them....the more the better....But, no worries on the panels radiating heat down onto the bimini / into the cockpit.....the opposite is usually true, the bimini cloth (Red Sunbrella on my current bimini) under the solar array is cooler than the dodger cloth (same Red Sunbrella) with no panels above it!!!

Nolex 77…Keeping the panels cool helps a lot, 6 inches clearance is great, but difficult to achieve in practice. Boats have the advantage of a reasonably strong airflow and and half inch or so is fine. Many panels are attached, or even glued to the deck, while this not ideal it still works.

???My White Stamoid Vinyl does not get that hot, but for tropics, is there any type or color (blue/black) that is more efficient, or is this just marketing hype?

Rainy monsoon season in SE Asia is intense, so I need to keep cockpit area dry as liveaboard

??? Has anyone seen solar panels installed and sealed together to be leak proof, or do you need to maintain space between panels??
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Old 20-12-2012, 19:11   #15
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Re: Solar Panel Mounting on Bimini

Quote:
Originally Posted by Pelagic View Post
Thanks mbianka… if I understand correctly from your blog, you removed the canvas and replaced with solar panels…. So full circulation underneath??

I was hoping to be able to leave the Stamoid Vinyl Bimini in place for rain protection and just install short attachment risers for the Solar panel framework. This would leave about one inch air space between the Solar panels and Vinyl.
My concern is that the panels need more circulation on the underside.

Alternatively, if that is not enough space, I can look at removing the vinyl and fashion a waterproof solution to mount panels on a modified Bimini frame…. (but I believe that would be much harder to do)
That's correct I removed the vinyl material and have the back of the solar panels open. The rear panels are 48 volt and their size just happened to make a nice bimini that covers the much of the cockpit and keeps the helmsman pretty dry in rain and shaded in sun. The forward two 75 watt 12 volt panels have a piece of Lexan between them keeping the forward area dry and also allow one to keep an eye on the sail. I will eventually also incorporate it to collect water too. I'm also planning on using a small strip of Lexan or cloth in the small space between the forward and aft panels. But, that is on the to do list as most of the cockpit is already covered and little water comes through the opening. Eventually, I may add roll up side panels too.
THE BIANKA LOG BLOG: SOLAR BIMINI PART SEVEN: PANELS INSTALLED
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