Solar Panel Options on a Cat

[ctsbillc]

I like those flexible panels: They are monocrystalline, so they will not suffer from shade as much as the polycrystalline panels shown in the video.

I have two similar panels, though not so efficient, on my boat is South Florida, and although mounted horizontally, with no pivot to point at the sun, they give 1/2 their rated power in the Florida winter, which is pretty good. Mine are covered with PET plastic, rather than glass, which is rated a "good" for resistance to solar degradation. Not sure how good the plastic coating will hold up over a decade, but after two years service it is still fine.

I purchased mine, and the MPPT controller, off the internet direct from China, and I'd advise do an ebay search to get the best product for the best price.

[StarryHorizons]

Originally Posted by thinwater

I choose to mount rigid panels on the hard top, but not under the boom area. This gives me walking and boom access while still allowing me to use more efficient and durable rigid panels and without unsightly/unseaworthy added constructions. I think the space under and near the boom contributes very little output, on the average. With a little hunting, you can find some pattern of panels that fits well and has symetry in capacity. If they cover something for which you may need access, design for easy removal.

When not sailing it is also feasible to move the boom off to the side to clear any shaddows. Use the preventer.

When you are sailing, do you notice a large drop in output due to shading from the boom/sails/etc?

[ctsbillc]

Flexible does not mean less efficient, as they are the same cells without the glass cover. Look for the monocrystalline types, easily recognized because they start life as a round slice of wafer with the edges trimmed off to make them squarish.

On the durability issue, I do have concern over the life of the plastic coating on the flexible types - glass obviously lasts forever in the sun, plastics do not.

[socaldmax]

Originally Posted by ctsbillc

Flexible does not mean less efficient, as they are the same cells without the glass cover. Look for the monocrystalline types, easily recognized because they start life as a round slice of wafer with the edges trimmed off to make them squarish.

On the durability issue, I do have concern over the life of the plastic coating on the flexible types - glass obviously lasts forever in the sun, plastics do not.

Flexibility in itself doesn't, but if you measure the output in watts/sft or sqmeter, they always produce less. Also, I may have missed it, but I haven't seen anyone post up that they got 100% power output from their flexible panels, under any conditions. My understanding is that reasonably priced flexible panels are drastically over rated, and flexible panels that put out rated power are drastically overpriced compared to rigid panels.

In the FL sun, even in the winter, you should be getting more than 50%. I bought some used 205w Sanyo panels for 75 cents/watt, and they put out their exact rated output when tilted toward the sun in socal in Feb.

I do share your concerns about the plastic coatings on flexible panels, but there might be a chance to refurbish it like they do headlight lenses. I have some spray polish for plexiglass/Lexan that also does an amazing job on hazy plastic.

[ctsbillc]

Efficiency of the cells is the useful measure, that equates to the watts sq ft. Mine are a few years old at 18% Those at EVTV Motor Verks Store: Flexible Solar Panel 180w, Solar, Boat and Golf, 180wsolarpanel are better than 20%, excellent.

They are also acrylic covering, which is excellent for sun resistance (Like sunbrella fabric).

My flex cells are giving exactly what they should, as they are not tilted, sun is around 30 degrees to the panel, and sine 30 = 0.5.

[Oliver L.]

Amy,

we got our solar mounted on the davits. When you're sailing you cannot always avoid shading, but it is limited. At anchor it helps to move the traveler to the side - at least in the Caribbean, since your bow there usually is due west.

We have 5 working panels of 100 W each. If one gets even partial shading, we lose 20% of the power.

The nice thing with this position is that the dinghy is in the shade.

I have seen flexible panels on several boats but I have yet to meet anyone in person who is satisfied with them.

Oliver

[roetter]

Originally Posted by ctsbillc

I like those flexible panels: They are monocrystalline, so they will not suffer from shade as much as the polycrystalline panels shown in the video.
...

Could you direct me to the source of this information? I can not see why mono-crystaline cells would be any different to poly-crystaline cells with regards to shading.

[roetter]

Why solar and not generator or engine running to charge batteries.

1 - Engines are noisy. I do sailing and anchoring to enjoy the quite nature.
2 - Engines are smelly. Nothing worse than smelling the diesel fumes of a generator running nearby.
3 Engines are dirty - more than we once had black soot on our deck in the morning dew from a generator running nearby most of the night.
4 Charging lead acid batteries to 100% full past 80% takes several hours with next to nothing gong into the batteries. Yet if you do not fully charge them once a week to full, you reduce their cycle life.
5 You are lucky to get 40A out of a 100A alternator as they are not designed for hot environment and regulate down very quickly. You can spend upwards of $1500 in an alternator updgrade or but a lot of solar for that money. Even with 100A your ngine is hopelessly underloaded and will die of bore glazing a very premature death. That will be much more expensive than a huge solar installation.

We run our cat with 1800W of solar. Never use engine to charge, have no generator.

We run our washing machine (home style front loader) at least 2 loads a week.
We make at least 200 gallons of water a week with our water maker.
We run our water heater (wife wants showers), coffee maker, toaster, light, navigation, you name it with - soon also inductive cooking to keep the galley cooler.

- no noise
- no pollution
- no wear and tear
- happy neighbours
- happy wife

Around noon we see over 100A coming in from our solar for a total of more than 500Ah per day. I would need to run one of our engines for over 12 hours for that, as our 100A alternator regulates down to about 40A within minutes due to heat. A generator would have to run about 4 hours for that same energy with my already fairly large 120A charger.

[cwjohm]

Let us deal with a few home truths.

Most cruisers actually move from one place to another, so the use of motors is not under no load. As such the batteries will be charged every time you move. If you live on a mooring and never go anywhere then solar may well be a good option. The argument about running motors unloaded is then moot.

There is an implicit assumption that generators are noisy and smelly. Whilst a poorly installed generator can be so, a well installed unit is neither. Certainly, my Fischer Panda installed in the forward hatch can hardly be heard and the exhaust outlet (underwater) exudes no fumes.

In a hot climate my preference is for air conditioning at least to cool the owners hull prior to sleeping. Air conditioning requires a generator.

I freely admit that my partner is a washing fanatic so twice a week will not cut it I am afraid. Typically about 1000a/h per week. Accordingly most people will install a generator if they have a washing machine.

Whilst some may cruise in an area where the sun always shine the majority do not, so I would hate to be caught in a week or so of rain and overcast skies and be entirely dependent on solar.

So the solar is not used/needed when :

(a) It is not available
(b) When not running the motors moving from place to place
(c) When not running the generator for other purposes.

As to how often solar is required will vary from person to person, but in most instances actual usage dictates that large solar arrays can only be justified for other reasons as elaborated here and not on pragmatic or financial grounds.

This is why solar arrays are an "afterthought" for production boat builders as described by the OP.

This is not to be critical of those with large arrays of solar panels. I drive a Lexus hybrid. I am not sure why as it cannot be justified on any grounds, compared to a normal production family car. I guess it is just because the hybrid concept is pretty cool and I have the money. If you have the money and it makes you feel good then go for it.

[thinwater]

Originally Posted by StarryHorizons

When you are sailing, do you notice a large drop in output due to shading from the boom/sails/etc?

If one is shaded, sure, that panel drops considerably. However, often reflection from the white sail greatly increases the light to the other panel, so often the drop is only about 30%. Often nothing is shaded, for example broad reaching or sailing away from the sun. And sometimes the penalty is severe, with everything shaded. In truth, the seasonal variation is the killer (winter has short, dull days).

There are several reasons, other than aesthetics, that I do not and will not mount panels over the davits:
1. We lash kayaks on top of the davits. Much better and less in the way than the common side deck storage.
2. We often have a bike rack over the davits. Same reasons.
3. It is handy to load the dingy and get into the dingy in rough conditions between the davits.
4. The structure adds weight, which should be a negative for every cat sailor. Even worse that it is aft and at the far end (pitching).
5. They catch wind.

I'd sooner look at soft panels... which is why I'm following the thread. The price will drop.

[socaldmax]

Let us deal with a few home truths.

Most cruisers actually move from one place to another, so the use of motors is not under no load. As such the batteries will be charged every time you move. If you live on a mooring and never go anywhere then solar may well be a good option. The argument about running motors unloaded is then moot.

There is an implicit assumption that generators are noisy and smelly. Whilst a poorly installed generator can be so, a well installed unit is neither. Certainly, my Fischer Panda installed in the forward hatch can hardly be heard and the exhaust outlet (underwater) exudes no fumes.

In a hot climate my preference is for air conditioning at least to cool the owners hull prior to sleeping. Air conditioning requires a generator.

I freely admit that my partner is a washing fanatic so twice a week will not cut it I am afraid. Typically about 1000a/h per week. Accordingly most people will install a generator if they have a washing machine.

Whilst some may cruise in an area where the sun always shine the majority do not, so I would hate to be caught in a week or so of rain and overcast skies and be entirely dependent on solar.

So the solar is not used/needed when :

(a) It is not available
(b) When not running the motors moving from place to place
(c) When not running the generator for other purposes.

As to how often solar is required will vary from person to person, but in most instances actual usage dictates that large solar arrays can only be justified for other reasons as elaborated here and not on pragmatic or financial grounds.

This is why solar arrays are an "afterthought" for production boat builders as described by the OP.

This is not to be critical of those with large arrays of solar panels. I drive a Lexus hybrid. I am not sure why as it cannot be justified on any grounds, compared to a normal production family car. I guess it is just because the hybrid concept is pretty cool and I have the money. If you have the money and it makes you feel good then go for it.

I think I'm going to disagree a bit here.

From what I've read, most cruisers spend far more time stationary than sailing. Even when moving, they might motor in and out of mooring fields or anchorages, but they would prefer to sail if the wind cooperates.

So really, if one moved once per week, and ran the engine for 2 hrs to get out and 2 hrs to get in, that's 4 hrs of engine running/charging for that week. At 50 or 60 amps, thats 200 - 240 amps total. Not much in the big scheme of things.

For those who want to run the AC, then genny hours rack up pretty fast, with the attendant fuel costs, maintenance and wear and tear, assuming no defect causing an early demise and total replacement of the unit. Seems like marine equipt., like watermakers, gennys, engines and saildrives aren't as reliable as their land based counterparts like diesel pickup trucks or gennys.

The cost of solar really isn't that great if you shop around. My last purchase of 3280 watts of 205 watt Sharp panels was $2800, total. I also bought 2 working 4000 watt grid tie inverters (home use) for $400 total. That was a fluke, but the solar panels were more in line with recent prices, say $1/watt or so.

I'm planning on a lot of solar power, backed up with an onboard 7kw genny, backed up with a Honda 2000. Hopefully the panels and Honda can run one A/C comfortably, if I need to cool both hulls and salon, run the big genny for the A/Cs and let the solar panels handle all other loads.

Once installed, solar panels are silent, free, non smelling, etc. Maybe I'm hyper sensitive to diesel exhaust, but I've never been on a boat with a running diesel engine that didn't have a detectable to overwhelming exhaust smell.

Even on overcast or partially cloudy days, solar panels still put out a surprising percentage of their output. Much more than when they are shaded by nearby objects.

[socaldmax]

Originally Posted by thinwater

If one is shaded, sure, that panel drops considerably. However, often reflection from the white sail greatly increases the light to the other panel, so often the drop is only about 30%. Often nothing is shaded, for example broad reaching or sailing away from the sun. And sometimes the penalty is severe, with everything shaded. In truth, the seasonal variation is the killer (winter has short, dull days).

There are several reasons, other than aesthetics, that I do not and will not mount panels over the davits:
1. We lash kayaks on top of the davits. Much better and less in the way than the common side deck storage.
2. We often have a bike rack over the davits. Same reasons.
3. It is handy to load the dingy and get into the dingy in rough conditions between the davits.
4. The structure adds weight, which should be a negative for every cat sailor. Even worse that it is aft and at the far end (pitching).
5. They catch wind.

I'd sooner look at soft panels... which is why I'm following the thread. The price will drop.

Speaking of flexible, there was a company called Nanosolar I followed with interest back in 2009. His vision was a huge thin film coated with nano particle ink, applied with inkjet printers, then sealed with another sheet. He had a lot of detractors but he actually succeeded in producing 50 MW of thin film solar sheet, unfortunately eventually he went BK.

The beauty of it was that it could be sold as a solid sheet you could cut and glue down, like shelf paper. You could cover all horizontal surfaces and just make cutouts for hatches, vents, etc and the majority of the roof would be covered with a single amorphous sheet, with only 1 pair of wires per sheet.

Nanosolar developed and briefly commercialized a low-cost printable solar cell manufacturing process. The company started selling panels mid-December 2007, and planned to sell them at around $1 per watt. When first announced that was just one fifth the price of the silicon cells, but in 2012 brand name assembled solar panels sell from around $1.30 reducing Nanosolar's cost advantage significantly.

The company uses copper indium gallium diselenide—which achieves up to 19.9% efficiency in laboratory samples—to build their thin film solar cells. Nanosolar's solar cells have been verified by NREL to be as efficient as 14.6% in 2006, 15.3% in 2009, and 17.1% in 2011. Efficiencies for current production panels are said to be 8-9%, with plans to submit panels with 10-11% efficiency for IEC certification in the fall of 2010.

Sure would be nice if someone could make flexible thin film work, especially with a nonskid surface!

[EllesBelles]

Originally Posted by roetter

...

I have since moved to 6x300W (1800W - $US1600) on a Lagoon 450. The forward cross beam is attached to the top of the columns holding up the cockpit roof. The aft cross beam is attached to the ghurad rail in front of the dinghy. Very simple, very light (less than 150 lbs for the support structure) and very inexpensive. It consist of 2 aluminum cross beams, custom made supports on top of columns, common deck 3 hinges, some 1" SS tubes. some common bimini fittings. Done.
....

Roetter, Can you please share what brand you went with for the 300W panels, and where you bought them too if you're recommend them.
Thanks

[EllesBelles]

Originally Posted by ctsbillc

....

I purchased mine, and the MPPT controller, off the internet direct from China, and I'd advise do an ebay search to get the best product for the best price.

ctsBill, Can you give us more information about what brand of larger panels you went with (if they were name brand) and what internet source you used to purchase them? How long did they take to arrive from China, and were they shipped in such a way that breakage isn't likely? Could you pay by US credit card?
Thanks

[ctsbillc]

Originally Posted by EllesBelles

ctsBill, Can you give us more information about what brand of larger panels you went with (if they were name brand) and what internet source you used to purchase them? How long did they take to arrive from China, and were they shipped in such a way that breakage isn't likely? Could you pay by US credit card?
Thanks

On the shading issue, it's about what the cell in the shade looks like when the sunlit cells are trying to push current though it. With the mono cell, they have a lower voltage drop.

I really like the panels referenced in this thread, I think they're better than the ones I have, as they are more efficient, and the Arylic coating will probably last longer than the PET coating on mine.

Mine I got from ebay, and the vendor I used does not have a decent selection anymore. I'd do a check on ebay, but the link in this thread may well be cost competitive with what's available on ebay.