ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
esc to dismiss
Solar Panels on Bimini with Split Backstay
|
Tim,
This is where quality and good design come into play. A panel can be designed to be less affected by shading by how the cells are wired and the quality of the cells.
We have 2 150w Solara panels mounted over the bimini. The split backstay has little discernible effect on the power output. The radar pole has some effect, but I’ve never taken the time to figure out how much, too much work and too many variables to account for. When I look at the daily out put of both panels they are very close to being even. When planning the design expect to get about 3x the nominal output on average; a 100w panel will average 300wh of power. Again, better quality and more efficient panels will tend to do better. Earlier this week my panels were producing a little over 500wh of power each under clear blue skies at ~30° N in late February. In summer they have produced over 600 wh a day each. Total panel output will also depend on battery type and charge state. With LFP batteries the panels stay in the bulk stage for much longer. With LA batteries their output would go in absorption and put out less current.
Another advantage of higher quality panels is smaller size. The Solara’s were 3 or 4” narrower than similar panels from other brands.?
Dave Second Star S362 #113 Fair Haven, NY/Lake Ontario
 d
toggle quoted message
Show quoted text
On Mar 1, 2025, at 11:32?AM, Tim Sowerby via groups.io <tim.sowerby2@...> wrote:
With a split backstay, is there a concern about shading from the stay itself? ? (There's also an issue with shade from pole mounted radar installations.)
?
I understand that some panels have substantially decreased output with very moderate shading whereas others are designed to be shade tolerant. ? ?In many ways the bimini seems like the best place to install flexible panels being out of the way and having less shade than the dodger. ? Considering the number of bimini installations out there, I'm beginning to think that shading from the backstay is more theoretical and real.
?
Perhaps those with split backstays and bimini might comment. ?Is backstay shading a valid concern? ?Are there specific panel arrangements i.e. four 50W panels with separate MPPT controllers vs two 100 W panels with a single controller preferable? ?Are there specific panel brands/models that are more shade tolerant. ?
?
Tim
Tim Sowerby
White Rose S426?
Sausalito CA ?
|
Tim,
Call these guys who are experts.? |
Please consider the environment before printing this email. Thank you.
toggle quoted message
Show quoted text
On Mar 1, 2025, at 9:54?AM, David Lochner via groups.io <davelochner@...> wrote:
?
Tim,
This is where quality and good design come into play. A panel can be designed to be less affected by shading by how the cells are wired and the quality of the cells.
We have 2 150w Solara panels mounted over the bimini. The split backstay has little discernible effect on the power output. The radar pole has some effect, but I’ve never taken the time to figure out how much, too much work and too many variables to account for. When I look at the daily out put of both panels they are very close to being even. When planning the design expect to get about 3x the nominal output on average; a 100w panel will average 300wh of power. Again, better quality and more efficient panels will tend to do better. Earlier this week my panels were producing a little over 500wh of power each under clear blue skies at ~30° N in late February. In summer they have produced over 600 wh a day each. Total panel output will also depend on battery type and charge state. With LFP batteries the panels stay in the bulk stage for much longer. With LA batteries their output would go in absorption and put out less current.
Another advantage of higher quality panels is smaller size. The Solara’s were 3 or 4” narrower than similar panels from other brands.?
Dave
Second Star
S362 #113
Fair Haven, NY/Lake Ontario
<9FCE91F8-92D1-4B86-AA1B-47EE394D5163_1_105_c.jpeg>
d
On Mar 1, 2025, at 11:32?AM, Tim Sowerby via groups.io <tim.sowerby2@...> wrote:
With a split backstay, is there a concern about shading from the stay itself? ? (There's also an issue with shade from pole mounted radar installations.)
?
I understand that some panels have substantially decreased output with very moderate shading whereas others are designed to be shade tolerant. ? ?In many ways the bimini seems like the best place to install flexible panels being out of the way and having less shade than the dodger. ? Considering the number of bimini installations out there, I'm beginning to think that shading from the backstay is more theoretical and real.
?
Perhaps those with split backstays and bimini might comment. ?Is backstay shading a valid concern? ?Are there specific panel arrangements i.e. four 50W panels with separate MPPT controllers vs two 100 W panels with a single controller preferable? ?Are there specific panel brands/models that are more shade tolerant. ?
?
Tim
Tim Sowerby
White Rose S426?
Sausalito CA
?
I hear these guys have a lot of experience with solar and can probably give some solid advice.?
|
Jeff?
toggle quoted message
Show quoted text
On Mar 2, 2025, at 1:39?AM, Tony Billera via groups.io <tony.billera@...> wrote:
? Tim,
Call these guys who are experts.?
Please consider the environment before printing this email. Thank you.
On Mar 1, 2025, at 9:54?AM, David Lochner via groups.io <davelochner@...> wrote:
?Tim,
This is where quality and good design come into play. A panel can be designed to be less affected by shading by how the cells are wired and the quality of the cells.
We have 2 150w Solara panels mounted over the bimini. The split backstay has little discernible effect on the power output. The radar pole has some effect, but I’ve never taken the time to figure out how much, too much work and too many variables to account
for. When I look at the daily out put of both panels they are very close to being even. When planning the design expect to get about 3x the nominal output on average; a 100w panel will average 300wh of power. Again, better quality and more efficient panels
will tend to do better. Earlier this week my panels were producing a little over 500wh of power each under clear blue skies at ~30° N in late February. In summer they have produced over 600 wh a day each. Total panel output will also depend on battery type
and charge state. With LFP batteries the panels stay in the bulk stage for much longer. With LA batteries their output would go in absorption and put out less current.
Another advantage of higher quality panels is smaller size. The Solara’s were 3 or 4” narrower than similar panels from other brands.?
Dave
Second Star
S362 #113
Fair Haven, NY/Lake Ontario
<9FCE91F8-92D1-4B86-AA1B-47EE394D5163_1_105_c.jpeg>
d
On Mar 1, 2025, at 11:32?AM, Tim Sowerby via groups.io <tim.sowerby2@...> wrote:
With a split backstay, is there a concern about shading from the stay itself? ? (There's also an issue with shade from pole mounted radar installations.)
?
I understand that some panels have substantially decreased output with very moderate shading whereas others are designed to be shade tolerant. ? ?In many ways the bimini seems like the best place to install flexible panels being out of the way and having
less shade than the dodger. ? Considering the number of bimini installations out there, I'm beginning to think that shading from the backstay is more theoretical and real.
?
Perhaps those with split backstays and bimini might comment. ?Is backstay shading a valid concern? ?Are there specific panel arrangements i.e. four 50W panels with separate MPPT controllers vs two 100 W panels with a single controller preferable? ?Are
there specific panel brands/models that are more shade tolerant. ?
?
Tim
Tim Sowerby
White Rose S426?
Sausalito CA
?
--
Jeff B
1988 Sabre 34-2, 347
S/V Northwood
Deale, MD
Yes Everything Dave said. One reason I put another panel on the davits was to surround the radar poll. In the worst case scenario there are always at least two panels in full sun. When the radar dome covers a good portion of a panel it does cut it down a good
bit. The back stays really are not noticeable. I have noticed during the middle of the day with high sun, the angle of the sun to the panel makes more of a deference than I would have thought. My two panels on the Bimini are angled slightly outboard and I
can see a difference in output when the sun angle slightly favors one side or the other. This has lead me to believe that on average flat is better.?
toggle quoted message
Show quoted text
On Mar 1, 2025, at 12:53?PM, David Lochner via groups.io <davelochner@...> wrote:
Tim,
This is where quality and good design come into play. A panel can be designed to be less affected by shading by how the cells are wired and the quality of the cells.
We have 2 150w Solara panels mounted over the bimini. The split backstay has little discernible effect on the power output. The radar pole has some effect, but I’ve never taken the time to figure out how much, too much work and too many variables to account
for. When I look at the daily out put of both panels they are very close to being even. When planning the design expect to get about 3x the nominal output on average; a 100w panel will average 300wh of power. Again, better quality and more efficient panels
will tend to do better. Earlier this week my panels were producing a little over 500wh of power each under clear blue skies at ~30° N in late February. In summer they have produced over 600 wh a day each. Total panel output will also depend on battery type
and charge state. With LFP batteries the panels stay in the bulk stage for much longer. With LA batteries their output would go in absorption and put out less current.
Another advantage of higher quality panels is smaller size. The Solara’s were 3 or 4” narrower than similar panels from other brands.?
Dave
Second Star
S362 #113
Fair Haven, NY/Lake Ontario
<9FCE91F8-92D1-4B86-AA1B-47EE394D5163_1_105_c.jpeg>d
On Mar 1, 2025, at 11:32?AM, Tim Sowerby via groups.io <tim.sowerby2@...> wrote:
With a split backstay, is there a concern about shading from the stay itself? ? (There's also an issue with shade from pole mounted radar installations.)
?
I understand that some panels have substantially decreased output with very moderate shading whereas others are designed to be shade tolerant. ? ?In many ways the bimini seems like the best place to install flexible panels being out of the way and having
less shade than the dodger. ? Considering the number of bimini installations out there, I'm beginning to think that shading from the backstay is more theoretical and real.
?
Perhaps those with split backstays and bimini might comment. ?Is backstay shading a valid concern? ?Are there specific panel arrangements i.e. four 50W panels with separate MPPT controllers vs two 100 W panels with a single controller preferable? ?Are
there specific panel brands/models that are more shade tolerant. ?
?
Tim
Tim Sowerby
White Rose S426?
Sausalito CA
?
--
Randy Drummond
Dazzle S38 mk2 206
Miami
|
Out of curiosity I took a look a 8 days of solar output by panel. The whole time the boat was in a slip facing more or less South. Port panels would get morning sun, but a bit limited by a large powerboat to the east. The radar pole is on the port side, which in this case is also the north side. The difference in out put for each panel is pretty negligible. With the starboard panel having a slight advantage, probably due to shading by the powerboat to port. Overall the differences amounted to about 2-3%. There was a couple of outliers that could be due to weather, since this is a retrospective study, I don’t have the climate data readily available.?
The panels are 2 150 watt Solar Panels with independent Victron controllers, mounted flat over the bimini. The data is from late February at about 31°N latitude. For most (all?) of the days we were living aboard.
Dave Second Star S362 #113 Fair Haven, NY/Lake Ontario
toggle quoted message
Show quoted text
On Mar 2, 2025, at 12:04?PM, Randy Drummond via groups.io <SVReleaseMe@...> wrote:
Yes Everything Dave said. One reason I put another panel on the davits was to surround the radar poll. In the worst case scenario there are always at least two panels in full sun. When the radar dome covers a good portion of a panel it does cut it down a good bit. The back stays really are not noticeable. I have noticed during the middle of the day with high sun, the angle of the sun to the panel makes more of a deference than I would have thought. My two panels on the Bimini are angled slightly outboard and I can see a difference in output when the sun angle slightly favors one side or the other. This has lead me to believe that on average flat is better.?On Mar 1, 2025, at 12:53?PM, David Lochner via groups.io <davelochner@...> wrote:
Tim,
This is where quality and good design come into play. A panel can be designed to be less affected by shading by how the cells are wired and the quality of the cells.
We have 2 150w Solara panels mounted over the bimini. The split backstay has little discernible effect on the power output. The radar pole has some effect, but I’ve never taken the time to figure out how much, too much work and too many variables to account for. When I look at the daily out put of both panels they are very close to being even. When planning the design expect to get about 3x the nominal output on average; a 100w panel will average 300wh of power. Again, better quality and more efficient panels will tend to do better. Earlier this week my panels were producing a little over 500wh of power each under clear blue skies at ~30° N in late February. In summer they have produced over 600 wh a day each. Total panel output will also depend on battery type and charge state. With LFP batteries the panels stay in the bulk stage for much longer. With LA batteries their output would go in absorption and put out less current.
Another advantage of higher quality panels is smaller size. The Solara’s were 3 or 4” narrower than similar panels from other brands.?
Dave Second Star S362 #113 Fair Haven, NY/Lake Ontario
<9FCE91F8-92D1-4B86-AA1B-47EE394D5163_1_105_c.jpeg>d On Mar 1, 2025, at 11:32?AM, Tim Sowerby via groups.io <tim.sowerby2@...> wrote:
With a split backstay, is there a concern about shading from the stay itself? ? (There's also an issue with shade from pole mounted radar installations.) ? I understand that some panels have substantially decreased output with very moderate shading whereas others are designed to be shade tolerant. ? ?In many ways the bimini seems like the best place to install flexible panels being out of the way and having less shade than the dodger. ? Considering the number of bimini installations out there, I'm beginning to think that shading from the backstay is more theoretical and real. ? Perhaps those with split backstays and bimini might comment. ?Is backstay shading a valid concern? ?Are there specific panel arrangements i.e. four 50W panels with separate MPPT controllers vs two 100 W panels with a single controller preferable? ?Are there specific panel brands/models that are more shade tolerant. ? ? Tim
Tim Sowerby
White Rose S426?
Sausalito CA ?
|
Nice data. Thanks. ?
Please consider the environment before printing this email. Thank you.
toggle quoted message
Show quoted text
On Mar 2, 2025, at 10:50?AM, David Lochner via groups.io <davelochner@...> wrote:
? Out of curiosity I took a look a 8 days of solar output by panel. The whole time the boat was in a slip facing more or less South. Port panels would get morning sun, but a bit limited by a large powerboat to the east. The radar pole is on the port side, which in this case is also the north side. The difference in out put for each panel is pretty negligible. With the starboard panel having a slight advantage, probably due to shading by the powerboat to port. Overall the differences amounted to about 2-3%. There was a couple of outliers that could be due to weather, since this is a retrospective study, I don’t have the climate data readily available.?
The panels are 2 150 watt Solar Panels with independent Victron controllers, mounted flat over the bimini. The data is from late February at about 31°N latitude. For most (all?) of the days we were living aboard.
Dave Second Star S362 #113 Fair Haven, NY/Lake Ontario
On Mar 2, 2025, at 12:04?PM, Randy Drummond via groups.io <SVReleaseMe@...> wrote:
Yes Everything Dave said. One reason I put another panel on the davits was to surround the radar poll. In the worst case scenario there are always at least two panels in full sun. When the radar dome covers a good portion of a panel it does cut it down a good bit. The back stays really are not noticeable. I have noticed during the middle of the day with high sun, the angle of the sun to the panel makes more of a deference than I would have thought. My two panels on the Bimini are angled slightly outboard and I can see a difference in output when the sun angle slightly favors one side or the other. This has lead me to believe that on average flat is better.?On Mar 1, 2025, at 12:53?PM, David Lochner via groups.io <davelochner@...> wrote:
Tim,
This is where quality and good design come into play. A panel can be designed to be less affected by shading by how the cells are wired and the quality of the cells.
We have 2 150w Solara panels mounted over the bimini. The split backstay has little discernible effect on the power output. The radar pole has some effect, but I’ve never taken the time to figure out how much, too much work and too many variables to account for. When I look at the daily out put of both panels they are very close to being even. When planning the design expect to get about 3x the nominal output on average; a 100w panel will average 300wh of power. Again, better quality and more efficient panels will tend to do better. Earlier this week my panels were producing a little over 500wh of power each under clear blue skies at ~30° N in late February. In summer they have produced over 600 wh a day each. Total panel output will also depend on battery type and charge state. With LFP batteries the panels stay in the bulk stage for much longer. With LA batteries their output would go in absorption and put out less current.
Another advantage of higher quality panels is smaller size. The Solara’s were 3 or 4” narrower than similar panels from other brands.?
Dave Second Star S362 #113 Fair Haven, NY/Lake Ontario
<9FCE91F8-92D1-4B86-AA1B-47EE394D5163_1_105_c.jpeg>d On Mar 1, 2025, at 11:32?AM, Tim Sowerby via groups.io <tim.sowerby2@...> wrote:
With a split backstay, is there a concern about shading from the stay itself? ? (There's also an issue with shade from pole mounted radar installations.) ? I understand that some panels have substantially decreased output with very moderate shading whereas others are designed to be shade tolerant. ? ?In many ways the bimini seems like the best place to install flexible panels being out of the way and having less shade than the dodger. ? Considering the number of bimini installations out there, I'm beginning to think that shading from the backstay is more theoretical and real. ? Perhaps those with split backstays and bimini might comment. ?Is backstay shading a valid concern? ?Are there specific panel arrangements i.e. four 50W panels with separate MPPT controllers vs two 100 W panels with a single controller preferable? ?Are there specific panel brands/models that are more shade tolerant. ? ? Tim
Tim Sowerby
White Rose S426?
Sausalito CA ?
|
My sincere thanks to all who contributed to the posts Solar Panel posts below. ?They have been very helpful in my decisions to build a system for my boat. ?One area that remains a bit of a mystery to me is how much solar wattage is safe and appropriate for a given amount of house bank Ah and daily draw. ?Specifically, my 12v system consists of a 500Ah AGM house bank with a 92% SOH which yields an actual 460Ah. ?My calculated daily usage is 100Ah/day at anchor and 115Ah/day sailing. ?The goal is to be independent of alternator (Balmar 100A with 614 voltage regulator) charging for 4-5 days or longer. ?Two seperate options are under consideration. ? Both include 3 SunPower Monocrystalline - Shade Tolerant Semi-flexible panels mounted on the Bimini and dodger totaling either 465 or 395 Watts.? The 465 Watt option produces 214.5Ah/day for a 5-6 hour ideal solar day, and with a partially cloudy day reduction of 70%, it produces 150Ah/day. ?The 395 Watt option procduces 181.5 Ah/day with 127 Ah/day (same 70% reduction) under partly cloudy conditions. ?Each of the three panels will be connected to separate Victron MPPT controllers.
My understanding is that excess wattage is sent back to the panels by the controllers in the form of heat energy. ?Is this correct or am I missing something??
How much solar power is too much for the above configuration? ?Is there a concern regarding excess heat due to the excess wattage, especially in full sun high temperature days? ?Is there a concern for damage to the canvass due to excess heat?
Any comments would be greatly appreciated.
Don Fleming
Duet
S-38-1 #77
Hudson River
?
|
Don,
Nigel Calder estimates that on average a solar panel will produce 3 times its nominal output, this has been consistent with my experience. Higher quality panels will do a little better, lesser quality panels a little worse. This puts the 465w array at about 1400wh (115 ah) a day, not the 214 ah the marketing ?department wants you to believe. The 3x estimate works well for the middle latitudes in the typical sailing season.?
I’ve used my panels with both LA batteries and LFP batteries, performance with ?LFP batteries has been much better than with the LA batteries (Fireflys). The best I ever saw with LA batteries was 4x, the best I”ve seen with LFP batteries has been 5 times, a little over 1500wh out of a 300 watt array on a brilliant sunny early spring day in Florida charging LFP batteries. With the LFP batteries the solar panels are always in the bulk mode, the batteries take whatever the panels produce. This was not the case with LA batteries, as the SOC increased on them, the amount of current they could take decreased.
I don’t think you’ll have problems with your batteries and either the 465 or 395 array, the out put difference over the course of a day will be pretty minimal 1185 wh vs1395 wh, a difference of about 17ah, about 3% of the battery's capacity. There are enough variables in the conditions that you probably wouldn’t notice the difference. The real life difference might be even less give the controller will (should) cut back the output as the batteries approach 100% SOC and AGMs being LA batteries the last 10-15% of the SOC goes very slowly as the battery ability to absorb more current decreases.
I am not knowledgeable enough about the electronics to opine in any meaningful way about what the controller does with extra power. Some controllers, such as the Victrons have a separate “Load” ?output. The controller can be programmed to dump any excess capacity into the load out put which can then be put to use to heat water, run lights or whatever. I don’t think you need to worry about too much solar capacity and battery capacity.
Sun Power makes a lot of PV cells and they are a good brand. However, not all Sun Power cells are the same. The quality and efficiency of the cells depends on what part part of the crystal it is slice from. Some parts of the crystal are much more efficient than other parts. One way to tell is the pane'ls price and dealer reputation, better panels, i.e. more efficient panels cost more. There is a company out west that uses Sun Power cells and has a good reputation. At one point Calico Skies Youtube channel offered a discount code for that company. Maybe Bill or Grace will chime in on this.
?You didn’t mention how many controllers you planned to use. There are pros and cons to wiring the panels in series with one controller or parallel with individual controllers ?for each panel. I’m in the each panel gets its own controller camp. This helps to reduce negative effects from shading and provides some redundancy if one panel or controller goes down.
Hope this helps.
Dave Second Star S362 #113 Fair Haven, NY/Lake Ontario
toggle quoted message
Show quoted text
On Apr 12, 2025, at 2:22?PM, Oceans via groups.io <oceans100t@...> wrote:
My sincere thanks to all who contributed to the posts Solar Panel posts below. ?They have been very helpful in my decisions to build a system for my boat. ?One area that remains a bit of a mystery to me is how much solar wattage is safe and appropriate for a given amount of house bank Ah and daily draw. ?Specifically, my 12v system consists of a 500Ah AGM house bank with a 92% SOH which yields an actual 460Ah. ?My calculated daily usage is 100Ah/day at anchor and 115Ah/day sailing. ?The goal is to be independent of alternator (Balmar 100A with 614 voltage regulator) charging for 4-5 days or longer. ?Two seperate options are under consideration. ? Both include 3 SunPower Monocrystalline - Shade Tolerant Semi-flexible panels mounted on the Bimini and dodger totaling either 465 or 395 Watts.? The 465 Watt option produces 214.5Ah/day for a 5-6 hour ideal solar day, and with a partially cloudy day reduction of 70%, it produces 150Ah/day. ?The 395 Watt option procduces 181.5 Ah/day with 127 Ah/day (same 70% reduction) under partly cloudy conditions. ?Each of the three panels will be connected to separate Victron MPPT controllers.
My understanding is that excess wattage is sent back to the panels by the controllers in the form of heat energy. ?Is this correct or am I missing something??
How much solar power is too much for the above configuration? ?Is there a concern regarding excess heat due to the excess wattage, especially in full sun high temperature days? ?Is there a concern for damage to the canvass due to excess heat?
Any comments would be greatly appreciated.
Don Fleming
Duet
S-38-1 #77
Hudson River
?
|
As the original poster of this thread back on 2/28 I also want to thank everyone for their helpful comments.? [A PC blue screen of death killed my laptop shortly after posting, then other events delayed continuing the thought process.? This past week the deck cleared sufficiently.]? ? My challenge has been finding panels that would lay on the canvas and fit in the available space: aft of the split backstay, not block a sight window to check on the main trim in the forward section, and to not have a panel lay across the middle support of the bimini.? Have attached a photo.? Do not want a frame above the bimini.? I believe a combination of 4 Solbian panels [2 x 82W and 2 x 54W, one of each on each side of the bimini] providing a nominal 272W is the best I can do.? These are the only panels I have found with dimensions that will fit in the available space.? Am trying to use stock panels and beat any additional tariffs, so custom panels are out of the equation. ? To use a Victron controller my understanding is the voltage has to exceed the battery by 5+V, and to make certain of that each pair would need to be wired in series and then to separate port and starboard controllers.? From my reading series wiring add volts but keeps the current at the lowest of the panels in the series.? A question: is the current the “open circuit” current on the spec sheet for the panel or the “maximum power point” current on the specs?? These panels both have open circuit (Isc) of 6A but their maximum power current is 4.5A and 6.8A, so will wiring them in series work at 6A or be reduced to the 4.5A, reducing the potential charging capacity of the array??? ? An alternative might be to wire the 2 larger 82W panels together in series and the 2 smaller 54W together, then to the controllers.? ? Any comments / suggestions are appreciated. ? Thanks, Brian Escapade? S426 ?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]> On Behalf Of Oceans via groups.io
Sent: Saturday, April 12, 2025 2:23 PM
To: [email protected]
Subject: Re: [SabreSailboat] Solar Panels on Bimini with Split Backstay? My sincere thanks to all who contributed to the posts Solar Panel posts below. ?They have been very helpful in my decisions to build a system for my boat. ?One area that remains a bit of a mystery to me is how much solar wattage is safe and appropriate for a given amount of house bank Ah and daily draw. ?Specifically, my 12v system consists of a 500Ah AGM house bank with a 92% SOH which yields an actual 460Ah. ?My calculated daily usage is 100Ah/day at anchor and 115Ah/day sailing. ?The goal is to be independent of alternator (Balmar 100A with 614 voltage regulator) charging for 4-5 days or longer. ?Two seperate options are under consideration. ? Both include 3 SunPower Monocrystalline - Shade Tolerant Semi-flexible panels mounted on the Bimini and dodger totaling either 465 or 395 Watts.? The 465 Watt option produces 214.5Ah/day for a 5-6 hour ideal solar day, and with a partially cloudy day reduction of 70%, it produces 150Ah/day. ?The 395 Watt option procduces 181.5 Ah/day with 127 Ah/day (same 70% reduction) under partly cloudy conditions. ?Each of the three panels will be connected to separate Victron MPPT controllers. My understanding is that excess wattage is sent back to the panels by the controllers in the form of heat energy. ?Is this correct or am I missing something?? How much solar power is too much for the above configuration? ?Is there a concern regarding excess heat due to the excess wattage, especially in full sun high temperature days? ?Is there a concern for damage to the canvass due to excess heat? Any comments would be greatly appreciated.
|
At the power level you are considering, just use 10ga wire and consider it a day. The ampacity rating for 10 ga is 60a, well above the amperage for the all of the panels combined. For a 3% loss 10 ga is good for about 60 roundtrip feet at 10 amps. Most of the time your panels will be well below 10 amps.
The spec to look at for the controller question is the Open Circuit Voltage. The higher the Voc the sooner the panel will start producing power or stated another way the more power it will produce in low light conditions, early morning, late afternoon, and overcast conditions. The 5v limit Victron has is less of an issue with high efficiency panels. Wiring the panels in series will bring the voltage above Victron’s threshold sooner at the cost of increasing vulnerability to shading. Shading is not as simple or consistent as it might seem. A few weeks ago I wrote about seeing no difference between panels on the port and starboard sides of the split backstay with an aft radar pole. A few weeks later in a different location I’m seeing a much larger difference ?depending on which way the boat is sitting on its mooring and the sun’s angle.
It might be worth considering having the 2 larger panels on independent controllers and the 2 smaller panels wired in series.?
Dave Second Star S362 #113 Fair Haven, NY/Lake Ontario
toggle quoted message
Show quoted text
On Apr 12, 2025, at 5:53?PM, Nauset Beach via groups.io <nausetbeach@...> wrote:
As the original poster of this thread back on 2/28 I also want to thank everyone for their helpful comments.? [A PC blue screen of death killed my laptop shortly after posting, then other events delayed continuing the thought process.? This past week the deck cleared sufficiently.]?? ? My challenge has been finding panels that would lay on the canvas and fit in the available space: aft of the split backstay, not block a sight window to check on the main trim in the forward section, and to not have a panel lay across the middle support of the bimini.? Have attached a photo.? Do not want a frame above the bimini.? I believe a combination of 4 Solbian panels [2 x 82W and 2 x 54W, one of each on each side of the bimini] providing a nominal 272W is the best I can do.? These are the only panels I have found with dimensions that will fit in the available space.? Am trying to use stock panels and beat any additional tariffs, so custom panels are out of the equation.? ? To use a Victron controller my understanding is the voltage has to exceed the battery by 5+V, and to make certain of that each pair would need to be wired in series and then to separate port and starboard controllers.? From my reading series wiring add volts but keeps the current at the lowest of the panels in the series.? A question: is the current the “open circuit” current on the spec sheet for the panel or the “maximum power point” current on the specs?? These panels both have open circuit (Isc) of 6A but their maximum power current is 4.5A and 6.8A, so will wiring them in series work at 6A or be reduced to the 4.5A, reducing the potential charging capacity of the array???? ? An alternative might be to wire the 2 larger 82W panels together in series and the 2 smaller 54W together, then to the controllers.?? ? Any comments / suggestions are appreciated.? ? Thanks, Brian Escapade? S426 ? ? My sincere thanks to all who contributed to the posts Solar Panel posts below. ?They have been very helpful in my decisions to build a system for my boat. ?One area that remains a bit of a mystery to me is how much solar wattage is safe and appropriate for a given amount of house bank Ah and daily draw. ?Specifically, my 12v system consists of a 500Ah AGM house bank with a 92% SOH which yields an actual 460Ah. ?My calculated daily usage is 100Ah/day at anchor and 115Ah/day sailing. ?The goal is to be independent of alternator (Balmar 100A with 614 voltage regulator) charging for 4-5 days or longer. ?Two seperate options are under consideration. ? Both include 3 SunPower Monocrystalline - Shade Tolerant Semi-flexible panels mounted on the Bimini and dodger totaling either 465 or 395 Watts.? The 465 Watt option produces 214.5Ah/day for a 5-6 hour ideal solar day, and with a partially cloudy day reduction of 70%, it produces 150Ah/day. ?The 395 Watt option procduces 181.5 Ah/day with 127 Ah/day (same 70% reduction) under partly cloudy conditions. ?Each of the three panels will be connected to separate Victron MPPT controllers. My understanding is that excess wattage is sent back to the panels by the controllers in the form of heat energy. ?Is this correct or am I missing something?? How much solar power is too much for the above configuration? ?Is there a concern regarding excess heat due to the excess wattage, especially in full sun high temperature days? ?Is there a concern for damage to the canvass due to excess heat? Any comments would be greatly appreciated.
|
Hi Don, addressing just the possibility of excess power being returned as heat energy, I don't believe this is the case. Power = current X voltage.? The controller limits the current so that the panels can be at full voltage but as little as zero current, ie zero power to the battery or into waste heat.? The efficiency would be dreadful if it converted excess power to heat. Bill Graves 2003 S362 #261 'Souwester' Marblehead, MA
My sincere thanks to all who contributed to the posts Solar Panel posts below.? They have been very helpful in my decisions to build a system for my boat.? One area that remains a bit of a mystery to me is how much solar wattage is safe and appropriate for a given amount of house bank Ah and daily draw.? Specifically, my 12v system consists of a 500Ah AGM house bank with a 92% SOH which yields an actual 460Ah.? My calculated daily usage is 100Ah/day at anchor and 115Ah/day sailing.? The goal is to be independent of alternator (Balmar 100A with 614 voltage regulator) charging for 4-5 days or longer.? Two seperate options are under consideration. ? Both include 3 SunPower Monocrystalline - Shade Tolerant Semi-flexible panels mounted on the Bimini and dodger totaling either 465 or 395 Watts.? The 465 Watt option produces 214.5Ah/day for a 5-6 hour ideal solar day, and with a partially cloudy day reduction of 70%, it produces 150Ah/day.? The 395 Watt option procduces 181.5 Ah/day with 127 Ah/day (same 70% reduction) under partly cloudy conditions.? Each of the three panels will be connected to separate Victron MPPT controllers.
My understanding is that excess wattage is sent back to the panels by the controllers in the form of heat energy.? Is this correct or am I missing something??
How much solar power is too much for the above configuration?? Is there a concern regarding excess heat due to the excess wattage, especially in full sun high temperature days?? Is there a concern for damage to the canvass due to excess heat?
Any comments would be greatly appreciated.
Don Fleming
Duet
S-38-1 #77
Hudson River
?
|
Thanks Dave, good information and suggestions.? Recall you mentioning quite a while back to use the open circuit, but thought it was the current not voltage.? The Voc of the larger panels is 17.5V so borderline for a VE controller, while smaller panels is 11.6V so would need to put them in series with something, either each other or paired with a larger panel.? Given your recent experience it may be best to do the latter to separate port / starboard with different controllers.? ? Some on the list have used other controllers, Genasun is one name I recall.? I did come across a Genasun Boost that may be an alternative.? Anyone familiar or have experience with them?? ? I sent an inquiry to OPE about the panels I am considering and will get their thoughts as well.? I had not gotten to wire gauge yet.? Given the relatively low levels do want to limit loss as much as possible.? ? Thanks, Brian ?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]> On Behalf Of David Lochner via groups.io
Sent: Saturday, April 12, 2025 10:33 PM
To: [email protected]
Subject: Re: [SabreSailboat] Solar Panels on Bimini with Split Backstay? At the power level you are considering, just use 10ga wire and consider it a day. The ampacity rating for 10 ga is 60a, well above the amperage for the all of the panels combined. For a 3% loss 10 ga is good for about 60 roundtrip feet at 10 amps. Most of the time your panels will be well below 10 amps. The spec to look at for the controller question is the Open Circuit Voltage. The higher the Voc the sooner the panel will start producing power or stated another way the more power it will produce in low light conditions, early morning, late afternoon, and overcast conditions. The 5v limit Victron has is less of an issue with high efficiency panels. Wiring the panels in series will bring the voltage above Victron’s threshold sooner at the cost of increasing vulnerability to shading. Shading is not as simple or consistent as it might seem. A few weeks ago I wrote about seeing no difference between panels on the port and starboard sides of the split backstay with an aft radar pole. A few weeks later in a different location I’m seeing a much larger difference ?depending on which way the boat is sitting on its mooring and the sun’s angle. It might be worth considering having the 2 larger panels on independent controllers and the 2 smaller panels wired in series.? ? Fair Haven, NY/Lake Ontario ? On Apr 12, 2025, at 5:53?PM, Nauset Beach via groups.io <nausetbeach@...> wrote: ? As the original poster of this thread back on 2/28 I also want to thank everyone for their helpful comments.? [A PC blue screen of death killed my laptop shortly after posting, then other events delayed continuing the thought process.? This past week the deck cleared sufficiently.]?? My challenge has been finding panels that would lay on the canvas and fit in the available space: aft of the split backstay, not block a sight window to check on the main trim in the forward section, and to not have a panel lay across the middle support of the bimini.? Have attached a photo.? Do not want a frame above the bimini.? I believe a combination of 4 Solbian panels [2 x 82W and 2 x 54W, one of each on each side of the bimini] providing a nominal 272W is the best I can do.? These are the only panels I have found with dimensions that will fit in the available space.? Am trying to use stock panels and beat any additional tariffs, so custom panels are out of the equation.? To use a Victron controller my understanding is the voltage has to exceed the battery by 5+V, and to make certain of that each pair would need to be wired in series and then to separate port and starboard controllers.? From my reading series wiring add volts but keeps the current at the lowest of the panels in the series.? A question: is the current the “open circuit” current on the spec sheet for the panel or the “maximum power point” current on the specs?? These panels both have open circuit (Isc) of 6A but their maximum power current is 4.5A and 6.8A, so will wiring them in series work at 6A or be reduced to the 4.5A, reducing the potential charging capacity of the array???? An alternative might be to wire the 2 larger 82W panels together in series and the 2 smaller 54W together, then to the controllers.?? Any comments / suggestions are appreciated.? My sincere thanks to all who contributed to the posts Solar Panel posts below. ?They have been very helpful in my decisions to build a system for my boat. ?One area that remains a bit of a mystery to me is how much solar wattage is safe and appropriate for a given amount of house bank Ah and daily draw. ?Specifically, my 12v system consists of a 500Ah AGM house bank with a 92% SOH which yields an actual 460Ah. ?My calculated daily usage is 100Ah/day at anchor and 115Ah/day sailing. ?The goal is to be independent of alternator (Balmar 100A with 614 voltage regulator) charging for 4-5 days or longer. ?Two seperate options are under consideration. ? Both include 3 SunPower Monocrystalline - Shade Tolerant Semi-flexible panels mounted on the Bimini and dodger totaling either 465 or 395 Watts.? The 465 Watt option produces 214.5Ah/day for a 5-6 hour ideal solar day, and with a partially cloudy day reduction of 70%, it produces 150Ah/day. ?The 395 Watt option procduces 181.5 Ah/day with 127 Ah/day (same 70% reduction) under partly cloudy conditions. ?Each of the three panels will be connected to separate Victron MPPT controllers. My understanding is that excess wattage is sent back to the panels by the controllers in the form of heat energy. ?Is this correct or am I missing something?? How much solar power is too much for the above configuration? ?Is there a concern regarding excess heat due to the excess wattage, especially in full sun high temperature days? ?Is there a concern for damage to the canvass due to excess heat? Any comments would be greatly appreciated. <Bimini.JPG>
?
|
We did this out of 1" tubing mounted on top of the bimini frame. 4 panels, 700 watts. The bimini window can see between the panels.  
|
Dave,?
Thanks for the valuable info from Nigel Calder. ?So much for the advice of the marketing departments! ?
FYI, The panels under consideration are Semi-flexible - SunPower Monocrystalline - Shade Tolerant as sold by Custom Marine Products. ? The Ocv for the 120W is 23.1, for the 140W is 25, and for the 155W is 28.9. ?Cell Efficiency for all panels is 24.4%, and all are Grade A+ SunPower cells. ?I'd like to believe these are reasonably high quality panels. ?Please confirm or deny my assumption. ?Each of the 3 panels will be connected to separate Victron Smart Solar MPPT 75-15 Solar Controllers. ?Is a rough estimate of improved efficiency with these cells and controllers possible?
Using Calder's formula, for the 465W array I am dividing the 1400Wh by 12.8v to get 109Ah/day, and for the 395W array x 3 = 1185Wh/12.8 = 93Ah/day. ?Does the formula call for division by 12.8 for AGM's or some other value like 12.0 or 13.0?
?
Brian,
I too have been working through the challenge of how to best place the panels on the Bimini. ?Custom Marine suggests using a sheet of 4mm Policarb-Double Walled under the solar panel to smooth out sharp the curve of the center bow to allow the panels to be placed lengthwise rather than athwart ship. ?I was concerned concerned about UV degradation when I researched this product. ?One of the flat sides is UV protected but the sides, which would be also exposed to sunlight, are not. ?
I cut some 1/4" masonite to match the size of the panels as an experiment and realized they do a nice job of smoothing out the sharp ridge caused by the center bow. ?I then tried placing the masonite on the bottom of the Bimini and it worked even better. ?As a result I plan to use 1/4" Starboard under the Bimini by modifying the center zipper to hold the pipe in place. ?I will send photos in a separate email.
?
Don Fleming
Duet
S-38-1 #77
Hudson River
?
?
|
Don,
There are so many variables that contribute to real life panel performance, it is important to not get too caught up in “precise numbers.” I think Calder uses the nominal voltage for his estimate, 12v. Anything from bird poop, to salt and dust buildup, to clouds, and shading can degrade panel performance. And in practice my Solar panels rarely hit the 150w output they are rated for. Even direction of travel. Today heading north under absolutely clear skies, my starboard panel produced 890 Wh. The port panel, next to the radar pole only produced 300 Wh due to shading a really small portion of the panel, this all because the sun was behind us. Had we been heading south, both panels would have produced in the same neighborhood. Nonetheless, I was still happy with the 1200 Wh (100ah) they produced, more than I ?consumed today.
My understanding of flexible panels is they are designed to flex over a firm surface, like a curved cabin top or hard dodger or bimini and not designed to be flexed. There are very fine wires and connectors in the panels, repeated flexing can cause these to break. The advice to mount them on something that won’t flex as much is good advice.?
Separating the panels into port and starboard makes more sense to me over orienting them athwartship. A shadow from the mast or sails will affect both panels if mounted athwartship but only one panel if the panels are oriented fore and aft.
Here’s the Calder article I referenced. It is getting a bit dated, however the basic information is still valid.
|
Dave
Second Star
S362 #113
Fair Haven, NY/Lake Ontario
toggle quoted message
Show quoted text
On Apr 13, 2025, at 8:11?PM, Oceans via groups.io <oceans100t@...> wrote:
Dave,?
Thanks for the valuable info from Nigel Calder. ?So much for the advice of the marketing departments! ?
FYI, The panels under consideration are Semi-flexible - SunPower Monocrystalline - Shade Tolerant as sold by Custom Marine Products. ? The Ocv for the 120W is 23.1, for the 140W is 25, and for the 155W is 28.9. ?Cell Efficiency for all panels is 24.4%, and all are Grade A+ SunPower cells. ?I'd like to believe these are reasonably high quality panels. ?Please confirm or deny my assumption. ?Each of the 3 panels will be connected to separate Victron Smart Solar MPPT 75-15 Solar Controllers. ?Is a rough estimate of improved efficiency with these cells and controllers possible?
Using Calder's formula, for the 465W array I am dividing the 1400Wh by 12.8v to get 109Ah/day, and for the 395W array x 3 = 1185Wh/12.8 = 93Ah/day. ?Does the formula call for division by 12.8 for AGM's or some other value like 12.0 or 13.0?
?
Brian,
I too have been working through the challenge of how to best place the panels on the Bimini. ?Custom Marine suggests using a sheet of 4mm Policarb-Double Walled under the solar panel to smooth out sharp the curve of the center bow to allow the panels to be placed lengthwise rather than athwart ship. ?I was concerned concerned about UV degradation when I researched this product. ?One of the flat sides is UV protected but the sides, which would be also exposed to sunlight, are not. ?
I cut some 1/4" masonite to match the size of the panels as an experiment and realized they do a nice job of smoothing out the sharp ridge caused by the center bow. ?I then tried placing the masonite on the bottom of the Bimini and it worked even better. ?As a result I plan to use 1/4" Starboard under the Bimini by modifying the center zipper to hold the pipe in place. ?I will send photos in a separate email.
?
Don Fleming
Duet
S-38-1 #77
Hudson River
?
?
Brian,?
I am having difficulty sending the photos. ?Will try again sometime in the early part of this week.
Don Fleming
Duet
S-38-1?
Hudson River
|
Dave,?
So helpful as usual. ?Thanks again.
Don
|
?Brian,
Attached are the photos of my masonite templates for solar panel backing plate plates. ?Four photos show the templates mounted on top of the Bimini. ?Note the problems with gaps between the canvas and the template. ?One photo shows the template mounted under the Bimini and over the center ridge pipe, and one photo shows a template (simulating a solar panels) mounted directly over the backing plate under the Bimini in the previous photo. ?This is the plan I will use. ?The tech guy at Custom Marine Products thinks it’s an excellent idea and gave it his blessing, for whatever that’s worth. ?My local canvass guy likes it too, and says modification to the center pipe zipper can be done at reasonable cost.
As previously stated I plan to make the actual backing plates out of 1/4” StarBoard with the edges rounded off because I think it is much better suited to the marine environment. I will mount the backing plates and the panels with appropriate length 10x24 bolts a washers in the fashion of the bolt kit available through Custom Marine Products. ?I will also have some grommets and 2” squares of reinforcing canvass add to the bolt holes, again at minimal cost.
Don Fleming
Duet
S-38-1 #77
Hudson River
|
Hi Don, ? I have read some people have used 4 mm polycarbonate as a backing and asked Ocean Planet about it, even going to 6 mm. ?They said not to do it and further they would not honor a warranty [5 years] claim if any panel were placed across a support frame.? The reason being as Dave mentioned, the repeated flexing over a hard point can damage the cells and wiring connections.? The manual for Solbian SP panels actually warns against doing that: ? “Canvas Installation - If installing on canvas, do not run any panels over a support bar. This was previously done with polycarbonate backing, but experience has shown that the solar panels can still be damaged by pressure from a crossbar.”? ? Using Starboard would probably flex less than polycarbonate, especially anchored to the support frame under the canvas.? I have only used 1” Starboard and that is not bending.? Would ?” Starboard adopt the various curves on top of the frame like the masonite?? Am not seeing how the zippers in the canvas to attach to the frame could be modified and still maintain adequate tension on the canvas across the full bimini frame.? [Possibly due to the coffee not kicking in yet.]? Would have thought having partial zippers vs. running the full length of the support frame would create uneven tension, but maybe not.? ? I looked at the Custom Marine but my fore / aft maximum length is 41”that will still fit inside the support frames, though that would go over the center support.? ? Please post more photos as your project progresses.? ? Thanks, Brian Escapade S426 CT / LIS ?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]> On Behalf Of Oceans via groups.io
Sent: Sunday, April 13, 2025 10:08 PM
To: [email protected]
Subject: Re: [SabreSailboat] Solar Panels on Bimini with Split Backstay? Attached are the photos of my masonite templates for solar panel backing plate plates. ?Four photos show the templates mounted on top of the Bimini. ?Note the problems with gaps between the canvas and the template. ?One photo shows the template mounted under the Bimini and over the center ridge pipe, and one photo shows a template (simulating a solar panels) mounted directly over the backing plate under the Bimini in the previous photo. ?This is the plan I will use. ?The tech guy at Custom Marine Products thinks it’s an excellent idea and gave it his blessing, for whatever that’s worth. ?My local canvass guy likes it too, and says modification to the center pipe zipper can be done at reasonable cost. As previously stated I plan to make the actual backing plates out of 1/4” StarBoard with the edges rounded off because I think it is much better suited to the marine environment. I will mount the backing plates and the panels with appropriate length 10x24 bolts a washers in the fashion of the bolt kit available through Custom Marine Products. ?I will also have some grommets and 2” squares of reinforcing canvass add to the bolt holes, again at minimal cost.
|
Don’s photo of the dodger clearly shows why panels should be oriented fore and aft. In that photo if the panels were oriented athwartship both panels would be shaded with their production severely curtailed by the boom’s shadow. If they are aligned fore and aft, only one panel would be affected.
Dave Second Star S362 #113 Fair Haven, NY/Lake Ontario
toggle quoted message
Show quoted text
On Apr 14, 2025, at 5:56?AM, Nauset Beach via groups.io <nausetbeach@...> wrote:
Hi Don, ? I have read some people have used 4 mm polycarbonate as a backing and asked Ocean Planet about it, even going to 6 mm. ?They said not to do it and further they would not honor a warranty [5 years] claim if any panel were placed across a support frame.? The reason being as Dave mentioned, the repeated flexing over a hard point can damage the cells and wiring connections.? The manual for Solbian SP panels actually warns against doing that:? ? “Canvas Installation - If installing on canvas, do not run any panels over a support bar. This was previously done with polycarbonate backing, but experience has shown that the solar panels can still be damaged by pressure from a crossbar.”?? ? Using Starboard would probably flex less than polycarbonate, especially anchored to the support frame under the canvas.? I have only used 1” Starboard and that is not bending.? Would ?” Starboard adopt the various curves on top of the frame like the masonite?? Am not seeing how the zippers in the canvas to attach to the frame could be modified and still maintain adequate tension on the canvas across the full bimini frame.? [Possibly due to the coffee not kicking in yet.]? Would have thought having partial zippers vs. running the full length of the support frame would create uneven tension, but maybe not.?? ? I looked at the Custom Marine but my fore / aft maximum length is 41”that will still fit inside the support frames, though that would go over the center support.?? ? Please post more photos as your project progresses.?? ? Thanks, Brian Escapade S426 CT / LIS ? ? Attached are the photos of my masonite templates for solar panel backing plate plates. ?Four photos show the templates mounted on top of the Bimini. ?Note the problems with gaps between the canvas and the template. ?One photo shows the template mounted under the Bimini and over the center ridge pipe, and one photo shows a template (simulating a solar panels) mounted directly over the backing plate under the Bimini in the previous photo. ?This is the plan I will use. ?The tech guy at Custom Marine Products thinks it’s an excellent idea and gave it his blessing, for whatever that’s worth. ?My local canvass guy likes it too, and says modification to the center pipe zipper can be done at reasonable cost. As previously stated I plan to make the actual backing plates out of 1/4” StarBoard with the edges rounded off because I think it is much better suited to the marine environment. I will mount the backing plates and the panels with appropriate length 10x24 bolts a washers in the fashion of the bolt kit available through Custom Marine Products. ?I will also have some grommets and 2” squares of reinforcing canvass add to the bolt holes, again at minimal cost.
|
Bill Graves
