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Old 22-04-2013, 03:41   #1
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How Big are Todays Solar Panels?

I'm thinking of putting some bigger solar panels on my boat....currently have 3 x 125W charging 12V batteries.

Anyone know what the current max size solar panels are?
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Old 22-04-2013, 04:58   #2
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Re: How Big are Todays Solar Panels?

I have no idea what the maximum size panel made measures, but for instance, the Grape Solar 390W modules measure 77.2 inches long, 51.5 inches wide and 1.57 inches deep, and each weighs 78.2 pounds.
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Old 22-04-2013, 06:06   #3
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Have a look at the Sunpower E20 327w panels. Most efficient panels available, which means most power for size & weight.
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Old 22-04-2013, 06:16   #4
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Re: How Big are Todays Solar Panels?

Huge panels are great if you never have partial shade. Otherwise check the cell configuration, you could lose all of the power if a corner is shaded where several smaller panels would work better.

I have 50 watt panels which have two separate circuits in each panel to help with this issue some. Maybe some of the larger panels have multiple circuits configured in parallel.

Another possibility (I'm not sure why it isn't more common) is to have active switching mosfets across every cell or two and a controller which can sense if a cell is shaded to bypass it. With peak power tracking controller you would still have great efficiency this way. Has anyone seen a system with this?
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Old 22-04-2013, 06:33   #5
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Re: How Big are Todays Solar Panels?

You also need to consider if a coconut drops on one in a storm or a wrench from up the mast. If you break one 50 in a set of 4 or 5 no big deal. If you crack your 300 watt in the middle you're screwed.
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Old 22-04-2013, 07:19   #6
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Originally Posted by boat_alexandra View Post
Huge panels are great if you never have partial shade. Otherwise check the cell configuration, you could lose all of the power if a corner is shaded where several smaller panels would work better.
Why do you write this? For the past decade(s), panels have had bypass diodes to take care of that. Big panels with dedicated MPPT controller is the most efficient setup, even though most don't have this.
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Old 22-04-2013, 07:36   #7
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Re: How Big are Todays Solar Panels?

SunPower 327watt panels are 61" x 41" inch and weigh 41 lbs
They are the highest output in the smallest, lightest package.
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Old 22-04-2013, 08:47   #8
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Re: How Big are Todays Solar Panels?

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Originally Posted by s/v Jedi View Post
Why do you write this? For the past decade(s), panels have had bypass diodes to take care of that.......
Why does Jedi keep trying to spoil threads on solar panels?

As the original poster said:
Quote:
Originally Posted by boat_alexandra View Post
.....check the cell configuration, you could lose all of the power if a corner is shaded where several smaller panels would work better.
I checked my expensive Solara panels which have bypass diodes and I got nearly zero out of the ones with partial shade. Jedi called my tests "flawed" - please ignore him on this subject. Bypass diodes "reduce" the problems of shade - they don't eliminate it.

It makes absolute sense to have four small panels distributed around the boat so that only one might get shade and the others produce full output.

Can anybody fault this logic?
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Old 22-04-2013, 09:22   #9
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Re: How Big are Todays Solar Panels?

My panels, which were purchased about eight years ago, but were obviously designed before that, do not have per-cell bypass diodes. Before installing them, I did a simple output-current test using a resistive load. The panels were 120W, 12V, and had two parallel strings of cells, which could have been connected in series for 24V operation. Shading one cell cut the output current essentially in half. Shading another cell in the other parallel branch cut the output current to practically zero.

Perhaps newer panels have per-cell bypass diodes, but mine sure don't. If I had, say, three or four panels in series, and a wide-range MPPT controller, then perhaps per-panel bypass diodes would do the job.

Anyway, I have my panels in parallel, and oriented as best I can to minimize the chance that a shadow will fall across all three panels. I will admit that my "on top of the dodger" panels are located to optimize aesthetics, not performance.
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Old 22-04-2013, 09:38   #10
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Re: How Big are Todays Solar Panels?

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SunPower 327watt panels are 61" x 41" inch and weigh 41 lbs
They are the highest output in the smallest, lightest package.
41lbs is light?

In any case, a panel like that will need a lot of support to make it shipshape, and I can't for the life of me see the advantages of getting a single huge one over several smaller ones. Now, if I had a cabin on the shore or in the woods somewhere ...
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Old 22-04-2013, 10:08   #11
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Re: How Big are Todays Solar Panels?

ST Micro makes a chip that will connect to a single solar cell, and use MPPT logic in its DC-DC conversion to upconvert from cell voltage to 5v output. Using this chip, you can combine ALL CELLS in parallel with 5v output, each cell will contribute its peak power to the total current at 5v. When shading is an issue, this is the best solution in my opinion. I intend to use this chip to combine all the flexible cells covering my 50ft boat.
So to answer the question, a "panel" CAN be as big as a 50ft boat.
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Old 22-04-2013, 10:22   #12
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Re: How Big are Todays Solar Panels?

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I intend to use this chip to combine all the flexible cells covering my 50ft boat. So to answer the question, a "panel" CAN be as big as a 50ft boat.
Actually I am planning to do exactly that - use as much deck space for solar as I can, on 52' boat. Did you try to estimate how much KW can you fit on average 50'? Just wonder what I can expect. I was thinking about 2 KW or more...
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Old 22-04-2013, 10:49   #13
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Re: How Big are Todays Solar Panels?

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Actually I am planning to do exactly that - use as much deck space for solar as I can, on 52' boat. Did you try to estimate how much KW can you fit on average 50'? Just wonder what I can expect. I was thinking about 2 KW or more...
I am rebuilding my cataraman to be primarily a solar powered boat, so it will have a quite large surface, 30ft wide, by 50ft long, is 1500 sq ft potentially.

For a monohull, they just don't have a lot of suitable deck space, and each one is different. The best is to have an arch off the stern which is out of the way and less shaded, and not the worst asthetics, can hang your dinghy too.
With the thin film lightweight flexible panels, another thought is to have them hinged off the sides, at least one side would be getting sun, could hinge them up when docking or remove them all together in bad weather. Not the most pretty idea. One can also just have floating panels on a raft, this might actually be best, although they will likely get stolen in a matter of hours..
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Old 22-04-2013, 11:10   #14
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Re: How Big are Todays Solar Panels?

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With the thin film lightweight flexible panels, another thought is to have them hinged off the sides, at least one side would be getting sun, could hinge them up when docking or remove them all together in bad weather. Not the most pretty idea. One can also just have floating panels on a raft, this might actually be best, although they will likely get stolen in a matter of hours..
Yeah, cat is another story... I will be monohulling I will be using thin film walkable panels and I am planning on embedding them to a deck surface, so nothing will be protruding.
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Old 22-04-2013, 11:37   #15
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Re: How Big are Todays Solar Panels?

Quote:
Originally Posted by nimblemotors View Post
ST Micro makes a chip that will connect to a single solar cell, and use MPPT logic in its DC-DC conversion to upconvert from cell voltage to 5v output. Using this chip, you can combine ALL CELLS in parallel with 5v output, each cell will contribute its peak power to the total current at 5v. When shading is an issue, this is the best solution in my opinion. I intend to use this chip to combine all the flexible cells covering my 50ft boat.
So to answer the question, a "panel" CAN be as big as a 50ft boat.
I assume you're talking about the ST SPV1040 chip. I've often thought about per-cell controllers, and wondered where the price/performance factors would be. The high-quantity applications such as home and industrial solar are fairly well-served by per-panel or per-array controllers and inverters, so I doubt if we will see widespread application of fine-grain controllers in panels that would be suitable for boats. Custom designs are certainly possible though.

I think the SPV1040 would be best used with groups of (say) four cells, which would still be a big improvement over a per-array design. The efficiency really falls off at one and two-cell voltage levels, no doubt due to the on-resistance of the integrated switching pass transistor. Still, it's a really interesting device. I like it!

Low-loss per-cell bypass diodes or MOSFET switches do remain a good solution for series-connected panels. I would like to see some specs for panels like this.
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