Challenges with Solar on boats

[newhaul]

Originally Posted by socaldmax

In the event of panel failure, yes, if you only have a single 300w panel and it fails, you're down to zero power, but in that case you're going to replace it as soon as possible, so it's only a temp. setback.

The final answer is don't install any panels in a shaded area.

Max if I have a failure of a single 100 watt panel in a 3panel array I still have 200 watts to carry me untill I can obtain a replacement. With a single 300 watt panel and it fails you have nada untill you replace it. Your statement implies that by having multiple panels one would become complacent and not effect repairs as soon as possible. That is utter bs. And we all know it. ( some statements I have read here are also called marketing)

[downunder]

Originally Posted by newhaul

Max if I have a failure of a single 100 watt panel in a 3panel array I still have 200 watts to carry me untill I can obtain a replacement. With a single 300 watt panel and it fails you have nada untill you replace it. Your statement implies that by having multiple panels one would become complacent and not effect repairs as soon as possible. That is utter bs. And we all know it. ( some statements I have read here are also called marketing)

Clearly newhaul you are a tiny panel man. Thats your choice.

By the same token if you have 2X 300w panels and one fails you still have 300 watts until you replace it. principle is the same.

[newhaul]

Originally Posted by downunder

Clearly newhaul you are a tiny panel man. Thats your choice.

By the same token if you have 2X 300w panels and one fails you still have 300 watts until you replace it principle is the same.

I agree with that . Most of my customers dont have a single.space.to dedicate to the size of a single 300 watt panel and avoid shading. A few can and.then I do go larger but never less than 2 panels if the total is more than 100 watts. To allow redundency for murphy.

[Kenomac]

Originally Posted by socaldmax

You have free will, you can install whatever you want. However, installing any panels where you know it's going to get shaded is pretty much a waste of time, money and energy, regardless of size. I'm not going to bother with every possible scenario in terms of size of shade, percentage of 300w panel vs percentage of 3 100w panels shaded, etc.

The first rule of installing panels is to not mount them in shade. Since one only gets power from unshaded panels, I still feel that it's more advantageous to install a larger, more efficient panel.

In the event of panel failure, yes, if you only have a single 300w panel and it fails, you're down to zero power, but in that case you're going to replace it as soon as possible, so it's only a temp. setback.

The final answer is don't install any panels in a shaded area.

The last time I checked, our boat still had a 75ft mast, boom and rigging attached. Kinda like a big tree without the leaves.

So now where is this place on a sailboat where we're supposed to mount these large solar panels that never gets shade?

[Stu Jackson]

Originally Posted by socaldmax

>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
The first rule of installing panels is to not mount them in shade.>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>

The final answer is don't install any panels in a shaded area.

OK, I've read ALL the solar topics for the past twenty years.

But this conclusions has me a little stumped.

It seems to me that there are two major issues here:

1. The sailboat is cruising, and, therefore, is in a different place every few days, could be in a different marina with a different orientation each day. This would result in different shading. Or the boat could be in different anchorages withe different tidal/current contributions, also resulting in different shading for a fixed array.

2. The boat is at a "home" marina, in a fixed slip, where the sun does a very predictable passage daily.

In #1, shading is VARIABLE and has no predictable "result." It will be what it is, where the panels are fixed on the boat anbd the boat swings to "whatever" conditions occur.

In #2 one would be able to predict where to place the panels or would live with the result of the orientation of the boat as the sun moves across the sky, but the shading would be predictable, and the location of the panels placed appropriately. [I had just this issue today in placing my small trickle panel: left side of dodger or right side.]

So, please help me understand the "don't install any panels in a shaded area..." mantra, given these two real world possibilities. Thanks.

[mitiempo]

Originally Posted by Kenomac

The last time I checked, our boat still had a 75ft mast, boom and rigging attached. Kinda like a big tree without the leaves.

So now where is this place on a sailboat where we're supposed to mount these large solar panels that never gets shade?

What you cannot eliminate you minimize. On a single masted boat first choice is an arch aft of the backstay, followed by the rails either side at the stern. Definitely not on the dodger under the boom unless it is the only option.

For a ketch there are shade issues just about everywhere.

[Kenomac]

Originally Posted by mitiempo

What you cannot eliminate you minimize. On a single masted boat first choice is an arch aft of the backstay, followed by the rails either side at the stern. Definitely not on the dodger under the boom unless it is the only option.

For a ketch there are shade issues just about everywhere.

A hideous looking set of expensive monkey bars hanging of the stern is your best answer?

How about thinking outside the "Jungle Gym" for a change and mounting multiple high efficiency panels on separate controllers on the bimini ( invisible from the water and onboard), with the boom pulled off to the side in anchorages with a flopper stopper attached?

Works for us and solves three issues. Invisible, unshaded solar and boat rocking.

[Stu Jackson]

Originally Posted by Kenomac

A hideous looking set of expensive monkey bars hanging of the stern is your best answer?

How about thinking outside the "Jungle Jim" for a change and mounting multiple high efficiency panels on separate controllers on the bimini ( invisible from the water and onboard), with the boom pulled off to the side in anchorages with a flopper stopper attached?

Works for us and solves two issues.

Ken,

Will you please stop being so reasonable and logical?

[mitiempo]

Originally Posted by Kenomac

A hideous looking set of expensive monkey bars hanging of the stern is your best answer?

How about thinking outside the "Jungle Gym" for a change and mounting multiple high efficiency panels on separate controllers on the bimini ( invisible from the water and onboard), with the boom pulled off to the side in anchorages with a flopper stopper attached?

Works for us and solves two issues. Invisible, unshaded solar.

If you have a bimini that works as well, but not every boat does. Some boats use solar as the bimini without canvas.

Not totally unshaded though if you have a mast with rigging on almost any boat.

I regularly see arches on boats with solar mounted in one of the best locations with wind gens and radar installed that shadows the panels - sort of defeats the purpose a bit.

[ramblinrod]

Originally Posted by socaldmax

If you did that, you'd be wasting your time, money, and valuable space on your boat. Why waste time bolting down 3 100w panels when you can simply bolt down 1 300w panel?

As I tell customers, I don't even pick up the drill for panels smaller than 200w.

Based on the prices at my distributor, 100w panels cost $65 (65cents/watt), his 280w panels are the big bargain at $86 ea (30.7 cents/watt), the 230w panels are $72 (31.3 cents/watt) and the 320w panels come in 3rd at $119 ea (37.2 cents/watt.) Why pay more for less? Another nice side benefit is I can use a cheap 20A controller connected to each 320w or 280w panel and get 20A or close to it at peak summer hrs and not worry about series connected panel shading or even shading losses in parallel from the loss of MPPT efficiency. Large panel efficiency and one controller per panel gives max MPPT harvest.

Finally, the 100w panels are quite often less efficient than the 300w panels, so not only do they take up a lot more space, they produce less power per sq ft, which is a bad thing on a boat. You want the most efficient use of your limited space.

Wow, I disagree with a lot of your philosophy. I advise customers that cost per watt is a very important consideration for on grid solar farms to achieve earliest break even and profitability, but on a boat, it's all about the application.

Some times larger panels may be the best way to go. Other times, smaller panels may be easier to configure in the available mounting real estate, and are certainly much easier to remove and stow for storage or in advance of a threatening storm. Just because one has solar, does not absolve them to be prudent and reduce windage when necessary.

[Kenomac]

Originally Posted by ramblinrod

Wow, I disagree with a lot of your philosophy. I advise customers that cost per watt is a very important consideration for on grid solar farms to achieve earliest break even and profitability, but on a boat, it's all about the application.

Some times larger panels may be the best way to go. Other times, smaller panels may be easier to configure in the available mounting real estate, and are certainly much easier to remove and stow for storage or in advance of a threatening storm. Just because one has solar, does not absolve them to be prudent and reduce windage when necessary.

RR,

We agree on something!! I knew if we kept at it long enough, that it would happen eventually.

[Mike OReilly]

Funny comment about never placing panels where shade might happen. Sounds like you only work on large power boats. As sailors have pointed out, that is impossible. There's always some shading somewhere on a sailboat. The thing to do is design your system with this in mind.

When I set up our panels I did it with the awareness that 1/2 the panels are going to be shaded much of the time. This is the argument for parallel vs series, smaller vs larger, but it also speaks to how you plan your system from the beginning.

[socaldmax]

Originally Posted by newhaul

Max if I have a failure of a single 100 watt panel in a 3panel array I still have 200 watts to carry me untill I can obtain a replacement. With a single 300 watt panel and it fails you have nada untill you replace it. Your statement implies that by having multiple panels one would become complacent and not effect repairs as soon as possible. That is utter bs. And we all know it. ( some statements I have read here are also called marketing)

No, I did not imply that. You inferred that. In either case, the owner will replace the failed panel(s) as soon as they get around to it. It might be a day or a week, but in the grand scheme of things, it's not going to be that long.

I prefer to look at it from the viewpoint of how much power are you going to get from your limited space while the system is working, since that's the entire purpose; to have a working system.

I prefer larger panels and max. solar power from the space available, I haven't had a customer yet who wanted smaller panels. As always, you're welcome to do as you please.

[jheldatksuedu]

I have a question about solar panel charge controllers, are there any things to watch out for or to look for when making a purchase. Do they typically take higher solar panel voltage and convert it to lower battery voltage and more charging amps, or do they just basically block current to keep the battery from over charging? How about low voltage from a shaded panel, do they convert that to battery voltage and less current to get some good out of it.

Is this what they do, (I would hope) or am I expecting too much from a $50 item?

[lifemiles]

I have 24 Solar panels running through 12 MPPT controllers each capabable of 100v max. This way, when the sun starts shining early on, the two panels conjoined deliver enough voltage to start charging a already (24v Batterybank)
The batterybank consists out of 24 x 2volt Gel battery's, 1500 Ah each, so I have 2 x 24v banks parallel delivering 3000 Ah. enough to run everything on my 130' yacht (lights all LED) including a professional sized fridge and freezer cell