Solar Panel Mounting on Bimini

[CAELESTIS]

Some thoughts . . .A friend in the S. Pacific measured heat under the bimini on two adjacent boats. One had Sunbrella Captains Navy, the other Sunbrella Oyster. The oyster boat was about 15 degrees cooler. He is a retired Boeing engineer, so I would expect his test to be fairly accurate.

If your panels need to run lengthwise, check out Sanyo. Their 225w panel is 63 x 32, a narrower configuration than Kyocera. The Sanyo panels are also supposed to maintain a higher output (10%) even when the ambient temperature is up high Sanyo HIT-225A01 Solar Panel

OutBack Power / Products / Charge Controllers / Flexmax

[Pelagic]

Shading:
Stuff I have read on websites about shading does concern me, so I need assurances and perspectives from real sailors that Solar panels on my Schooner Rig Bimini would be worth it??
See fear factor Word doc?

Same Photo shows boom position slightly lower than sail conditions as topping lift is fixed.
My Anchor plan with solar is to lower boom on top of bimini to minimize boom shade
Aft Sail is mostly a Reaching sail because of rigging limits, so often not even used if going downwind (except as steadying)

Discussions on choosing multiple MPPT and choosing panels with maximum by-pass diodes are all a bit confusing for a novice to prioritize, so I am making a spreadsheet of Solar Panel Types( Mono/Multi-crystal) with NOC ratings from 150 watt to 320 watt, to look at best fit.
I will share my findings when done.
Any additional guidance on real world decisions on panel type based on shading is appreciated.

[mbianka]

Originally Posted by Pelagic

??? Has anyone seen solar panels installed and sealed together to be leak proof, or do you need to maintain space between panels??

The rear 48 volt panels on my Bimini are butted up against each other and there is no need to maintain space between the panels. I could run a bead of caulk in the seam if water leakage was a problem but, don't find that to be the case. Of course we don't get many Monsoon rains here in the Northeast US only Hurricanes from time to time.

[Caribsailors]

2x 150 watt 24v in parallel through MPPT controller. I'm in the tropics so not that worried about shadowing. We have never had a lack of power to charge and run all electrical requirements during the day. Even when our dying fridge was drawing 9 amps and running 18hrs a day





I've had thoughts of installing a voltage reactive relay to switch the panel configuration to series in low solar conditions/shadowing, to keep voltage highest to controller. But like I said above, we have always had ample power supplied. Maybe if we move North........If we move north

[Sumner]

Originally Posted by Caribsailors

2x 150 watt 24v in parallel through MPPT controller. I'm in the tropics so not that worried about shadowing. We have never had a lack of power to charge and run all electrical requirements during the day. .......... Maybe if we move North........If we move north

Cool picture and no you don't want to go north. 8 degrees, snow on the ground and 30 mph winds here today ,

Sum

[Pelagic]

Originally Posted by Caribsailors

2x 150 watt 24v in parallel through MPPT controller. I'm in the tropics so not that worried about shadowing. We have never had a lack of power to charge and run all electrical requirements during the day. Even when our dying fridge was drawing 9 amps and running 18hrs a day

Nice installation… do you have any photos of the underside?

[Pelagic]

Heading to boat this weekend to start mapping things out.
I began this spreadsheet primarily to understand Solar Panel variations in size and what specs are marketed as important.
Not all used NOCT so this is not at all balanced or finished, but a place to begin.

I also don’t understand yet what rating numbers are important (other than cost).
So for deciding on a marine application, any comments on my sheet are appreciated.

Lastly, I see some specs call a Panel..Multicrystal and others Polycrystal… I am assuming that is the same thing??

[familycruisers]

2 Motec 250's 6x5 roughly built in usa Roughly $1watt
Midnite Solar Classic 150 built in usa $650
Bamm, youre done, besides wiring, mounting, batteries, etc, etc

[noelex 77]

Originally Posted by Pelagic

Heading to boat this weekend to start mapping things out.
I began this spreadsheet primarily to understand Solar Panel variations in size and what specs are marketed as important.
Not all used NOCT so this is not at all balanced or finished, but a place to begin.

I also don’t understand yet what rating numbers are important (other than cost).
So for deciding on a marine application, any comments on my sheet are appreciated.

Lastly, I see some specs call a Panel..Multicrystal and others Polycrystal… I am assuming that is the same thing??

The most important statistic is that the shape suits your space. Of course you can fit 2, 3, or more panels each side, so there are a number of permutations. All panels need to be the same
The next most important is the efficiency use the spreadsheet to calculate the watts per square meter or foot, rather than using the manufactures figures as they can refer to cell efficiency rather than panel efficiency. Use NOCT if you can but STC is OK. Obviously don't compare NOCT of one panel to the STC of another.

Fitting the most watts in your space ( leaving the most space around the boom) is what you aiming for which is combination of the above factors.

The Voc should be above 41v to avoid having a series connection it's probably worth crossing these off your list. I think your installation is going to best with a parallel electrical connection.

Look at the quality of construction. The quality of the company (some do slightly exaggerate). The guarantee.

More bypass diodes are a plus, put this on your spreadsheet.

Mono, poly (multi is same) is not important, but most the very efficient panels will be mono.

Finally the price is important remember freight can make a big difference.

Don't worry too much its hard to get wrong. The most important thing is to get a good reliable, secure and easy mechanical mounting with the most watts at a good price. If you do your homework you will be able to squeeze an extra 10% of power in the space and save some money. The prices are very variable for solar panels.

[ka4wja]

Pelagic,
1) Have you looked at mu set-up....

Originally Posted by Pelagic

do you have any photos of the underside?

I have plenty of photos, during the install and afterwards, including the underside....

Although these are from 2006....it is all still there and working great after 6 years and 12,000+ miles offshore (incl. multiple full gales, and one full tropical storm / tropical cyclone, etc.)...
Solar Panels

I hope these photos help....

Here is a more recent photo, after about 3 years and some 10,000+ miles....(note the rain water beeded up on the canvas from a passing shower....and the poor photo developing shows my canvas a bit orange, but it is red sunbrella...)
4711201



2) Pelagic, in your case you may be restricted by your existing bimini frame and boom, and whatever space you have for airflow under the panels is what you have....and that's it....
But, if you have a choice between 1" and 6", go with the 6"....it will allow for better airflow under the panels....(I have 6" to 10" between my bimini and my panels...)

As for airflow under the panels being important in the tropics, it is also important in latitudes in the 20*'s.....
I have personal experience with a similar boat to mine having the exact same set-up to mine (actually 4 x 135 watt panels vs. my 4 x 130 watt panels), sailing the same waters at the same time of year, etc....but they consistently have lower peak output during the highest production hours....usually about 4 - 5 amps less, for a few hours at least....
They've got the same wire, same controllers, same lack of shading, etc....
BUT...
But, their panels are mounted directly above their bimini, with little space for airflow....I think it is about 3/4" to 1" (about 2cm) of space .....

And, I have heard reports from other cruisers with almost idential set-ups, where one who has panels mounted in the clear have consistently higher outputs....

Again, not trying to insist that this is a necessity, just commenting that it is an important factor to consider in most installations....
(with Pelagic's vast area to mount panels, he can make up for any inefficiencies with a larger array....but some cruisers have much limited space and $$$)



Fair winds and sunny skies.....

John
s/v Annie Laurie

[gettinthere]

I mounted 2 140w panels directly to the frame. Seem to work well enough. Some shading from boom sometimes. Center cockpit so boom is over entire bimini top.

Solar panels do have a "grain" or direction. Lets say the panel is 4 columns wide by 20 rows. If you cut off one column, you still get 3 columns of production. But cut off one row and you loose all 4 columns...the entire panel. We placed the panels so that when the boom shadow is over the length of the panel, blocking one or 2 rows, we still get production from the remaining rows.

[Pelagic]

Originally Posted by noelex 77

The Voc should be above 41v to avoid having a series connection it's probably worth crossing these off your list. I think your installation is going to best with a parallel electrical connection.

Great guidance, Thanks again Nolex
For the Voc 41v limit, should I be using STC or NOCT (about 4V less) when making my shortlist?
I am assuming the reason behind a high Voc is that in poor solar conditions it will still flow at above 24.8Volts? (Just not sure how much leeway I have for parallel)

Has anyone found a consumer rating list using NOTC, as some of the manufacturers try their best to hide it!!

[Pelagic]

Originally Posted by ka4wja

Pelagic,
But, if you have a choice between 1" and 6", go with the 6"....it will allow for better airflow under the panels....(I have 6" to 10" between my bimini and my panels...)

As for airflow under the panels being important in the tropics, it is also important in latitudes in the 20*'s.....
I have personal experience with a similar boat to mine having the exact same set-up to mine (actually 4 x 135 watt panels vs. my 4 x 130 watt panels), sailing the same waters at the same time of year, etc....but they consistently have lower peak output during the highest production hours....usually about 4 - 5 amps less, for a few hours at least....
They've got the same wire, same controllers, same lack of shading, etc....
BUT...
But, their panels are mounted directly above their bimini, with little space for airflow....I think it is about 3/4" to 1" (about 2cm) of space .....

And, I have heard reports from other cruisers with almost idential set-ups, where one who has panels mounted in the clear have consistently higher outputs....

Again, not trying to insist that this is a necessity, just commenting that it is an important factor to consider in most installations....

Thanks Ka4wja and Gettingthere for the great photos, comparisons and advice.

John….Given that I live in the Tropics and now learning that the difference in performance between Standard Test Conditions (STC) and Nominal Operating Cell Temp (NOCT) reduces Watt rating by about 27-29%,…. I want to cool panels as much as I can.

I will find out tomorrow how much room the camber will give me with the +300Watt panels Nolex recommends…. If not enough, I may have to get inventive…

[mcarling]

Originally Posted by gettinthere

Solar panels do have a "grain" or direction. Lets say the panel is 4 columns wide by 20 rows. If you cut off one column, you still get 3 columns of production. But cut off one row and you loose all 4 columns...the entire panel. We placed the panels so that when the boom shadow is over the length of the panel, blocking one or 2 rows, we still get production from the remaining rows.

Are you sure about that? Solar cells are about 0.5V actual, 0.33V nominal. Every or nearly every 12V (nominal) panel has 36 cells wired in series. A 24V (nominal) panel has 72 cells wired in series. It's possible that a 12V panel somewhere has 36 pairs of paralleled cells wired in series, but I've never seen one.

It seems to me that panels have no "grain" but rather shading too many cells will cause the output voltage of the panel to drop below a usable threshold.

I would be interested to read a theory on how solar panels can have "grain" as described above.

[mrm]

Originally Posted by mcarling

It seems to me that panels have no "grain" but rather shading too many cells will cause the output voltage of the panel to drop below a usable threshold.

I would be interested to read a theory on how solar panels can have "grain" as described above.

No theory needed, rather practical understanding of how panels are assembled, what is the effect of shadowing a single cell in a series-arranged panel, and what bypass diodes are for.