Sailboat Solution - SBMSO only - Space is prime - which panels to install?

[ReinholdU]

Dacian and forum

(Finally) I am going to build my own solar system ...albeit on a Sailboat
I can fit 2 panels lengthwise across the rear of the 4m wide boat building a elevated carrier (unshadowed).
I could fit one panel each left and right along the mainsail boom where however a single will almost always be shadowed ('completely').

My preselection of panels is almost identical in price these days but quite different:
- Canadian Solar CS3W-415P HIKU        - Umpp: 36,3V
- Q.Cells Q.Peak DUO L-G5.2 395W    - Umpp: 48V
- Q.Cells Q.Peak DUO G8 355W         - Umpp: 33V

I'd like to use the Q.Cells 395Watt panels which makes the best mechanical fit
but the Umpp it quite different since it is 72 cell.
...Canadian solar is almost too wide aft, and the GUO G8 seems "a bit weak".

Left&right of the boom only Q.Peak DUO G8 355W will fit - but is this really useful? (50% shadow min)

Fund's are limited. I intend to minimize to a 24V 8s WB-LYP100A Winston battery setup.
I will use Dacian's SolarBMS SBMSO ...and (if it makes sense) 2! DSSR20 - no mpp, no alternator

Long term I could use solar to power an electrical dinghy motor ...heating&cooking.

Having no idea which panel solution will harvest "most effectively",
I decided to ask the forum for advice on what panels to install.

Any comment is appreciated.

Regards - Reinhold

P.S.: Can I buy a SBMSO tomorrow?  ;-)

[Dacian Todea]

Reinhold,

The Q.Cells Q.Peak DUO G8 355W are by far the best option to charge a 8s LiFePO4 as those are 60 cell panels.

Both of those other two panels are 72 cells and the extra 12 cells will be completely useless. While those panels have higher power rating they will not charge the battery with higher current than the 355W DUO G8

As for panels that are always shadowed that will not be useful.

The DUO G8 is made of two panels each made with 60 half cut cells so if the shadow effect one of those half only then the other half of the panel will not be affected but if shadow is on both halfs (shadow on the length of the panel then the panels will not produce anything).

You will be able to order the new SBMS0 from my website starting September 7th and shipping for those orders will be done about two weeks after that.  

[ReinholdU]

Thanks Dacian - was afraid you'd tell me that. ;-)

(I really don't like those LPG bottles on a boat.)

My goal was to make it to a 1000Watts peak...somehow

The incidence angle for the two back panels will be adjustable ...

...maybe on inspection I can make a 3rd panel (next to the mainsail)(out-of-shadow-) "shiftable"...

Best "service" 😇 in town (and beyond) - THANKS

Tty on the 7th then

Regards - Reinhold

[Barry Timm]

Reinhold, can't you build a wider overhead platform for the additional solar panels? 4 panels mounted across would be 4m wide? If nothing else, it would give you more shade in the cockpit! :) :)

[ReinholdU]

Hi Barry - thanks for livening things up!                               <intended to be humorous!...>

YES-You are right ...that's what kept me awake for some time now <smile>.
Let's assume YOU are a sailor ...so for the of sake the of the watching crowd:

(Useable) Panels "these days" come in "length" of 1._m-1.7m up to about 2m+ ...give or take.
Them panels are "about 1m wide" (that's why you made your comment) (tnx).
So yes "about 4m+ wide" and you get to put "4 in parallel" (at the stern of the boat).

Can do (in my case) ... it seems. However if I make them "inclineable" this means
that worst case (drop down) I have a "new Mainsail"...drop to max 8 square meter (OK mostly 3m^2)
right across the direction of travel ... "SOLAR BRAKE".
So - no inclination- rigid+flat . "YESs"... we now even save the cost of a bimini (non sailors:
"that's the sunshade above your head when you are steering in the cockpit"). YOU are always shadowed now.
WAIT: that mainsail-boom right above your head ...it moves... mostly "right above a few long panels" <sigh>

Luckily my boat is a catamaran (you guessed it). I thus _could_ make my boat "just a little bit wider",
make it "just a little bit longer" and "just cover only half of the cockpit" <grin>.
Unfortunately a lot of Marinas will now charge "10m class" and "catamaran special width box" fees <sigh>.
So much for "solar makes us free" ...(of marinas) <grin>.

WORSE after all this effort I still will be punished for "sailing (in the direction) towards the sun".
<Hmmh> Cut that mast ? SACRIFICES - make it a "truly SOLAR _nosail_ BOAT" !!! <BIG GRIN>

Go sailing - have fun

Reinhold

[Barry Timm]

Haha! 

I'm not a sailer but enjoy watching quite a few YT sailing channels! :) 

Personally, I think I would do the 4M wide flat configuration with no tilting because you're surely never going to have the boat oriented in one direction for long enough to take advantage. And you probably would get very tired of continously changing the tilt, and my guess is you will never be sailing in extremely low angles of sun as it is not usually conducive to enjoyable sailing climates with extreme cold. :) 

[Casey & Gina]

I really ought to have researched panels more before buying my 300W ones, as the extra wattage of something like these would make a better use of my limited roof space, and would essentially be the same as adding another panel since with 6 panels I’d get another ~300W out of the same space.

Ah well, live and learn.  I am however intending to buy some more panels in the future (probably before winter) to build an external/stationary tilted array in order to have enough power for heat when days get short and more likely overcast, so I’d like to do better.  If the new panels are the same size, I might even swap them out with the primary panels I already have since those are the ones always connected.

What are the important specifications to compare?  What to watch out for?  Should any 60-cell panels work okay?  I’m curious to hear how others chose their panels...  Lastly, I saw in a video comparing the SBMS with MPPT, and it seems that some energy goes to waste when the panel voltage gets too high compared to MPPT (though offset by better use of power other times).  Is that a more likely scenario with higher-wattage panels, which might offset the benefit, or do they just push more amps at the same voltage?  Is there a point at which the amperage of 2 panels may be too high for a DSSR20 (I’m guessing no)?

Thanks for any advice!

[ReinholdU]

Hi Barry - You said you are "not sailing" so let me add:

Sailing a yacht is actually a "slow moving" process.
You set course ("300°") and follow that...
- you either make a turn or make a jibe (rudder)
- sails shifted, (fine) adjust sails now ...and "done"
...Rudder and sails now will be "stable": "all" angles set
Unless (wind,wave) conditions shift you may "relax" now (^_*)
(in extremum that may be for days (downwind around z world))
("standing helm" is even hated by many long distance sailors: autopilot)

Watching YT vids sure may give a different impression
but that's boats(!), regatta, competition or "weather extremes".
(you won't see rigid solar panels anywhere (^_*))

If you sail on a big boat to the next island in the med
you usually will have plenty of time to tilt panels "a few times"
...definitely on a (non heeling) catamaran.
Note: Course fixes orientation but tilt is an "almost free" variable.
The optimum tilt angle "when you want to sail" is "far from flat or "0".
From mediterranean to north sea its around 30 to 40 degrees (give or take)
Canada North to Miami wouldn't be that different around 45 - to 28 deg.
(...you are on a boat so nothing's absolute, you will (just) "optimize")
BUT optimum tilt to horizontal/flat can be as much as +-30% gain.
https://web.stanford.edu/group/efmh/jacobson/Articles/I/TiltAngles.pdf

Go sailing  
Reinhold

(Note: sailors DO invite the curious)

[Barry Timm]

haha, OK. I admit, I tend to watch the small single hull videos mostly, with their wind-vane self-steering. Too much pitch and roll and course variation for tilting. I'm sure a stable, fully-electronic self-steering cat would be very different!

Regarding the rigid PV, I see them on YT videos all the time! Usually mounted on tall aluminum overhead structures over the rear of the cockpit. Seems like it's the best location for reduced shading.

[ReinholdU]

Hi Casey&Gina

Not sure whether I'm the right one to give advice on that but here are some notes:

- You want to use SBMS0 -> you WILL need matching batteries and panels.
...24V (8s) battery <-> 60 Si-Diode Panel...
(Dacian must have explained it a 1000 times but here the battery voltage fixes operation point.
24V LiFePO4 is close to Mpp of 60cells Si diode panels (@RT): MATCH
 (You need Mppt to deviate from 24V/60Diode Si-Panel)

- Expect shadowing? -> 2 "remedies" available:
 1) 60 Diodes are in series so orient your panel that NO COMPLETE Diode is shadowed
 if a single Diode is dark it will be very high Resistance -> 0 Amps harvest
 2) Use 120/2 "half" panels. At least Q.cells cut cells in half and make them "denser" and two parallel 60type panels in the same area.
 Mostly at least half of the panel keeps working.
 
 - Mobile?
 <don't laugh>! Sun rises in the east, is "strongest" at exact "high noon"@exactSouth" ...get's weak when we arrive ;)
 The incident angle of solar irradiation on panel does influence "harvest efficiency" quite significantly (see note to Barry)
 I assume you are an RVer. "Flat on the roof" parked in somewhat shadowy place is what I'd like to do <grin>....BUT
 Most panels are between 15% and 20% efficient. SunPower/LG/Hanwa(Q.cells)/REC (*)... are above 22% and "high" low light effective.
 Prices have come down a lot. I try to buy the most efficient optimally adepted to my available "unshadowed" space panel
 and (see above) make sure that when I harvest both orientations are as good as possible
 - imho RVers should use there "mobile" advantage to the max.
 
 - No Loss in circuit. tricks - multiple size panels
 Dacian uses about 16(?) "good price" panels ("a ton") set "sturdy in a fixed place for optimum heating in winter" (<grin>).
 Dacian has "cost optimized" SBMS0/DSSR20 for about 40A and #4 Wiring in each "string" - great attention to detail 👍
 My (sailing and your RVer(?) optimizations might be different - actually they WILL be.
 "On my Yacht's panels every electron count's - if I can afford it ;-)
 
 TRICKS:
 - On an RV I've rarely seen "small angled (no shadow) panels" "fitted" around skylights... DSSR20 here I come!
 - Have you seen YT vid's by EVERLANDERS? Jason is a genius at practical engineering.
 (Like he uses 4 smaller panels and stacks 2 on top of the other two) - go watch.
 
 Hope that helps
 Regards - Reinhold
 
 * more Panels in Europe ...look for "black" versions 

[Casey & Gina]

Hi ReinholdU, nice to “meet” you,

I’m not really an “RVer” per se, but close.  I am full time living in & building out a 7’x16’ cargo trailer into a tiny home for my family.  My panels are indeed flat - as the array is quite heavy and would need to all tilt together so the panels don’t shade each other.  It would require some sort of mechanical/electric system to lift into a tilt.  That’s feasible to do, but well beyond my own skills to engineer, and at best would mean adding considerable weight to the trailer.  So flat it is.  During winter I will probably just be in one place though, and will need a lot of energy for heating, so I am wiring 3 extra DSSR20s to ports in an access panel On the side of the trailer so that I can plug in an external tilted 6-panel array.   I have packed the roof with as many panels as possible - the array is actually slightly longer than 16 feet and overhangs the back of the trailer, and the two middle panels that surround my roof vent / skylight overhang the sides by a few inches - it has just enough to open.  I have a couple other smaller vents installed under the panels too - everything else is secondary to and built around the solar system.  The SBMS was the first part of that system I got, so everything is build around it.

What makes me different from 95%+ of RVers:

- I’m completely off grid - I never rely on or have access to the power grid.  I am building in a 50A power inlet, just in case I end up needing it, but I may never use it.  I don’t generally pay to stay at campgrounds, and would only do so if I became desperate for power in the winter.

- I have much more substantial insulation.  The walls, ceiling, and floor have 3.5 inches of XPS insulation - compared to 1 or sometimes 2 inches of less effective insulation in an RV or camper.

- I have no windows.  Aside from the solar panels installed on a ladder rack and a couple access panels on the sides of the trailer, it just looks like a normal cargo trailer.  This helps insulate a lot, since I don’t have a ton of big single-pane windows like most campers/RVs.

- I don’t need to park in shade to be comfortable as a result, so I choose where I park based on where the sun is going to be best.  As there’s around 8 inches between the roof and panels which cover most of the roof, this provides a shading effect and keeps the trailer cooler as well.  On the property where I am currently staying, there is an RV and another person’s camper.  They are parked in more shade than me, but if I go inside one of them when the midday sun is beating down, it’s quite unpleasantly hot inside.

- The trailer is 100% electric.  No propane, generator, or other secondary source of heat/power (other than human bodies - perhaps getting a pet would help keep the trailer warm too, haha).

I also have an old camper which I use for storage, a working kitchen as my new one is not built yet, and have been staying in for the past week as I have half my floor pulled out right now as I’ve been working on plumbing and wiring.  Waking up in the camper is a cold experience!  Using the same bedding, I sleep much more soundly in the new trailer and don’t feel cold when waking up, even using no heat.  The thin camper windows almost seem to radiate coldness...  I get the appeal of windows, but having many large single pane windows on a such a small space is certainly not very efficient.  I think maybe the bed also gets cold from underneath in the camper - there is an access panel on the back which opens into a storage compartment under the bed (some call this a “garage”), so there is nothing between the mattress and outside other than a sheet of plywood and a very thin layer of fiberglass that doesn’t seal.  It has a propane furnace I could run, but it’s uses a ton of fuel as the heat leaks away so fast/easily.  I can keep my new trailer comfortable with a single space heater, which cycles off a lot more than it’s on.  It has only gotten significantly cold (just below freezing) once for a couple days since starting this project, and I did not have all the wall insulation in yet at the time so there was more heat loss.  I was able to keep the inside comfortably warm all night using only a little over half the battery to do so.  I think it should do much better with all the insulation in place, the inside walls buttoned up, and sometime before winter having a means to cover the vents to outside with insulation.

I am currently using a SBMS0 and DSSR20s, and a 2p8s 400Ah battery bank.  I also have a SBMS40 that I never really put to use outside of brief testing.  The battery cells I have now are not the most size/weight efficient and have a life expectancy of 2000 cycles.  Knowing more now, I have researched and found cells which would save me close to 40% on size & weight, and have a life expectancy of 4000 cycles.  The only problem is the considerable cost I already have invested into what I have.  I have a van that could fit 3 60-cell panels, which I was thinking of using as an external array that I could plug in to the trailer sometimes.  But now I am thinking that I could put my current batteries and SBMS40 into the van so that it’s standalone and always able to reap energy if the sun is out and there is any battery depletion.  I could then use the van bank to charge the trailer bank as needed, and have substantial mobile power capabilities in the van as well. We’ll see what plays out.

It would be great to build a boat out one day, but I’m not sure that it’s in my cards.  For now I am content to enjoy that vicariously through folks like yourself. ;)  It must be provide a lot of great and unique experiences.  Yes, the optimizations will of course be different, but there are commonalities as well (limited solar space, not practical to tilt, etc.).  Hopefully we can inspire and learn from one another!

On Thursday, September 3, 2020 at 5:32:10 AM UTC-6 ReinholdU wrote:

Hi Casey&Gina

Not sure whether I'm the right one to give advice on that but here are some notes:

- You want to use SBMS0 -> you WILL need matching batteries and panels.
...24V (8s) battery <-> 60 Si-Diode Panel...
(Dacian must have explained it a 1000 times but here the battery voltage fixes operation point.
24V LiFePO4 is close to Mpp of 60cells Si diode panels (@RT): MATCH
 (You need Mppt to deviate from 24V/60Diode Si-Panel)

- Expect shadowing? -> 2 "remedies" available:
 1) 60 Diodes are in series so orient your panel that NO COMPLETE Diode is shadowed
 if a single Diode is dark it will be very high Resistance -> 0 Amps harvest
 2) Use 120/2 "half" panels. At least Q.cells cut cells in half and make them "denser" and two parallel 60type panels in the same area.
 Mostly at least half of the panel keeps working.
 
 - Mobile?
 <don't laugh>! Sun rises in the east, is "strongest" at exact "high noon"@exactSouth" ...get's weak when we arrive ;)
 The incident angle of solar irradiation on panel does influence "harvest efficiency" quite significantly (see note to Barry)
 I assume you are an RVer. "Flat on the roof" parked in somewhat shadowy place is what I'd like to do <grin>....BUT
 Most panels are between 15% and 20% efficient. SunPower/LG/Hanwa(Q.cells)/REC (*)... are above 22% and "high" low light effective.
 Prices have come down a lot. I try to buy the most efficient optimally adepted to my available "unshadowed" space panel
 and (see above) make sure that when I harvest both orientations are as good as possible
 - imho RVers should use there "mobile" advantage to the max.
 
 - No Loss in circuit. tricks - multiple size panels

 Dacian uses about 60(?) "good price" panels ("a ton") set "sturdy in a fixed place for optimum heating in winter" (<grin>).