Solar system???

Hey Guys and Gals,

I have a 40 footer with a genset, but thinking of going solar. I have a large flat open space on top of my pilothouse. There's no washing machine or A/C on my boat and it's docked 80% of the time. I'm a local SOCAL cruiser and don't plan on any trips lasting longer than a few days.

Any suggestions on what brand?
Cost?
Rigid or flexible panels?
How many or big of panel should I go?
Any local installers around Southern Ca for recommendations?

Input from anybody with systems already installed would be great. What would you have changed or done different? Should i wait for better technology?

Thanks,

Josh

I'm not ultra knowledgeable about this, but my boat does have two 130 watt solar panels on it. From my observations so far, I have noticed that while at the dock, running only our refridgerator, occasional lights and dc stereo, our batteries are fully charged at the end of each day (central CA , spring and summer so far)

The way you describe your boating plans save your money. Contrary to popular belief solar energy is not free. Initial installation and maintenance cost more than you save for several years the way you say you boat. Use your generator and shore power. Its harder than you think to compete with the power company with solar Energy, Think about it there would be a lot more solar out there if it competed with the power company. Making hot water is a different story. Making hot water with solar is much more competitive. But then you only need so much hot water. Shore power and generator the way you boat, Put your solar money in the bank,

If you already have a house battery bank, 200 watts is more than enough to keep them charged and maybe run a couple lights. For the usage you described above, plugged-in 80 percent of the time, a big and costly solar panel/battery bank might not be worth the trouble unless you want to stay anchored out for long periods and hate the sound of a genset like I do.

obthomas said:

The way you describe your boating plans save your money. Contrary to popular belief solar energy is not free. Initial installation and maintenance cost more than you save for several years the way you say you boat. Use your generator and shore power. Its harder than you think to compete with the power company with solar Energy, Think about it there would be a lot more solar out there if it competed with the power company. Making hot water is a different story. Making hot water with solar is much more competitive. But then you only need so much hot water. Shore power and generator the way you boat, Put your solar money in the bank,

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My experience is different than what you have described. I dont know what the cost was for my solar system initially, but here is a complete 160 watt kit for 500 bucks;
Go Power! Overlander Solar Charging Kit - 160 Watt

What maintenance are you referring to? wiping the panels down once in a while?

I also do not need to be connected to shore power and we all know there are some advantages to that as well.

I'm putting 750W of solar on my Nordhavn. The parts cost for the panels, mounting rails, clamps, and feet, plus a top end MPPT charge controller was $1500. It will produce about 3KW per day, accounting for weather etc. Some days more, some days less. A diesel generator produces about 10KW/h for every GPH, so at $4/ gal of diesel that power costs $0.40/KWh. And that's the fuel cost alone without figuring in the costs of maintenance and amortizing the cost of equipment, so that number heavily favors the generator. I think it was somewhere on this site where a Calder article was discussed that figured the fully loaded cost of generator power at more like $1.00/KWh. Regardless, with the solar displacing generator power at $0.40/KWh, payback will be in about 3 years.

Those are just the hard numbers, and don't take into account a number of other factors. I don't like listening to a generator running if I can help it. If solar can reduce gen time while in a peaceful anchorage, that alone is worth it to me. Then there is the whole issue of top-off charge for your batteries. Nobody want to run their generator long enough to fully charge the batteries, so we all typically charge to 80% or so. With solar working away all day full charge will be reached much more frequently, thereby extending the life of the batteries.

So there are lots of factors that play into one's decision about going solar or not.

What determines the size/watts you will need? Is it for just charging the battery bank or running entire boat?

Capt.JB, go ahead, you will not regret it.
Often overlooked, well charged batteries, especially the lead acid kind, last much longer. Added battery life defrays solar install cost. Solar panels may improve, but there is no point waiting.
Panel watts, divided by volts(12) = amps. In theory. In practice you get about half that. The panels should be unshaded (your roof sounds ideal). Even a shadow, from say a rigging wire, compromises output.
How much panel depends on how much power you want to use, size of battery bank, willingness to use the genset, etc. I have 180 watts, I can feed a 12v fridge in daytime, and keep my batteries full. I do not have shorepower. I do have a genset.
The installation is essentially panels connected to a regulator (it has the diode to prevent power outflow at night) which connects to the batteries. The newest regulators are a more efficient "MPPT" type.
Panels, regulators, cabling, etc are readily available on Ebay, and elsewhere. Frame quality is important. Monocrystalline panels are/were best. I installed my own, even made up brackets to screw the panels to, using teak feet. I used Sikaflex to glue the feet to the deck to take up any irregularity, not screws, avoiding screwhole water entry risks, and panel flexing. My installation works fine after 3 years, I have no background in electrics, did my research, asked around, shopped around. You need a cooling air gap between panel and deck, around 1" will do.
TF member Rebel set out to replace his genset with solar, installing about 400 watts of panel. He may come in on this, last time we spoke he was happy.

Capt. JB said:

What determines the size/watts you will need? Is it for just charging the battery bank or running entire boat?

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I think you need to add up the total amp hours your boat will use on a given day at dock or a given day at anchor and make sure the solar system will generate the same amount of amp hours a day. (i think).

try here for some cool spreadsheets
http://www.coastalsolarsales.com/News---Info.html

Josh:

Well, the first thing you need to know is how many amphours of power you use in a 24 hour period on the hook. As one example I used about 80 amphours for lights, refrigeration and laptop charging.

How do you get that. Install a battery monitor. Every boat that hangs out on the hook for more than a day should have one.

If you are only going to be away from the dock for a maximum of 48 hours then in my case I need about 320 amphours of battery capacity. That will let the batteries discharge to only half of their capacity after 48 hours which is the recommended maximum.

If I occasionally stay out for more than 48 hours, I crank up the generator. Using an existing generator is much cheaper than installing solar panels.

So install a battery monitor. Check your amphour useage. Install more battery capacity. Run the generator if necessary.

Solar has its place, but more for longer term cruisers and those without a generator.

David

Capt. JB said:

What determines the size/watts you will need? Is it for just charging the battery bank or running entire boat?

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Chances are real good that the answer is "as much as you can fit". One of the challenges with a boat is that there is usually far less space available for solar than there is demand for power. In other words, physical space will be your limiting factor, not how much power you need. On really power hungry boats, the amount of solar there is room to fit isn't enough to make a meaningful dent the boat's power consumption. Other Nordhavn owners have warned me about this, but I have ignored them, determined to lower my electric loads enough to make the solar significantly helpful.

I don't think your boat falls into the power hungry category, but I also don't think you will regret putting as much solar up as you can. The panels are remarkably inexpensive at the moment. As an example, my 3 panels and mounts were about $1000, and the charge controller was $500. The controller can handle a lot more panels, so the incremental cost of more solar is relatively small. If only I had room.

Speaking of controllers, I would really recommend an MPPT controller. On land-based system the argument for MPPT has always been that you get more incremental power per $$ for MPPT than for adding more panels. The assumption, of course, is that you have ample room for as many panels as you might want.

On a boat you will almost always be panel space constrained, so the objective is to get as many watts of power per square foot as possible. An MPPT charger will get another 15% - 20% out of those square feet, maybe more. They also let you run higher voltage panels, and wire them in series for even higher voltage. This gives you a much greater selection of panels to select from so you can find something that is just right for your available space, and higher voltage means less current between the panels and charger controller, which means smaller wires which is always welcome when you have to fish them through the boat.

Great info guys! Here's a pic of my roof. Tons of space.

Capt. JB said:

Great info guys! Here's a pic of my roof. Tons of space.

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Load her up with 300+ watt house panels.

Is there a difference between a "house" or "marine" panel?

Capt. JB said:

Is there a difference between a "house" or "marine" panel?

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Yes there is $$$$$$$$$$$$$

Installed single 320 watt panel a month ago. Mppt controller takes care of charging. Mounted on top of pilot house, not ideal but have seen 23 amps. At home dock I have rolled up power cord. Panel takes care of batteries, reefer is left on.

fryedaze said:

Yes there is $$$$$$$$$$$$$(( difference between house and marine panels))

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Those sold by marine shops are the same as sold elsewhere. All are weather exposed. (Wonder about the effect of snow & ice, unlikely in CA).
As to comparing quality, search Ebay, you`ll find plenty to look at. If put off by Chinese manufacture, you`ll have trouble buying anything, though some will claim German design.
Even on your broad expanse of roof I see areas of rigging shading. Locate as best you can, usually as the sun moves, some are totally unshaded.
You can start with a bank of panels and add more later. You did not mention the size of your battery bank, if you want to be largely genset free, consider daily usage. If you start with 300 watts of panel, 300 div by 12 = 25 amps, multiply by say 6 hours = 150 amps a day, which I halve based on experience = 75amps a day.
Most regulators have terminals to directly power an appliance when power is available, independent of the battery. I`ve not done that, others may know if, with no sun, the appliance is then battery fed via the regulator.

A solar panel and MPPT charger will find its way onto my boat soon. They are ridiculously cheap and is foolish not to take advantage of IMO.

Happy batteries is a huge plus. My tiny little battery bank cost more to replace than that small system Bligh posted. If it plays a part in getting 3-4 extra years of battery life it has earned its keep on my boat.

Rebel112r said:

Installed single 320 watt panel a month ago. Mppt controller takes care of charging. Mounted on top of pilot house, not ideal but have seen 23 amps. At home dock I have rolled up power cord. Panel takes care of batteries, reefer is left on.View attachment 31446View attachment 31447

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Why would it not be "ideal"? Is it because of amp totals or location on the pilothouse? What brand of panel did you get? Where?

Thanks,

Josh

BruceK said:

Those sold by marine shops are the same as sold elsewhere. All are weather exposed. (Wonder about the effect of snow & ice, unlikely in CA).
As to comparing quality, search Ebay, you`ll find plenty to look at. If put off by Chinese manufacture, you`ll have trouble buying anything, though some will claim German design.
Even on your broad expanse of roof I see areas of rigging shading. Locate as best you can, usually as the sun moves, some are totally unshaded.
You can start with a bank of panels and add more later. You did not mention the size of your battery bank, if you want to be largely genset free, consider daily usage. If you start with 300 watts of panel, 300 div by 12 = 25 amps, multiply by say 6 hours = 150 amps a day, which I halve based on experience = 75amps a day.
Most regulators have terminals to directly power an appliance when power is available, independent of the battery. I`ve not done that, others may know if, with no sun, the appliance is then battery fed via the regulator.

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I have 3 large 8D batteries.

-Josh

Kyocera panel. Not ideal in location, be nice if it could follow sun. But for a fixed location it is just fine. Controller is midnite solars latest mppt controller, about 300 bucks, made in the North West. Called The Kid. All bought from a solar outfit in Flagstaff Az. Will find name in the AM.

Name of company, Northern Arizona Wind and Sun.

Thanks Rebel112r.

JB
Ideal panel positioning tracks the sun movement, or at least fixed towards the most efficient angle. In your area, this would be facing south and tilted about 45 degrees.

Laying flat still works fine; It just requires more panel area for the amp hours you use.

The difference in cost of panels is for higher efficiency. If you have lots of space for panels and a low power load, then just buy the cheapest panels. Or you can more efficient panels and use up less space. Another option is buying thin flexible panels that can be walked on, if you need regular access to your cabin roof. Lots of options depending on your requirements.

Take note of what Twistedtree says - he knows quite a bit re this - he powers an entire holiday cottage with solar alone most of the time. I like what I have, to augment the engine, and wind genny (Airbreeze), and I don't use any AC out on the pick. We run a 12v frig 24/7 tho.

I love solar though - I just like the thought of renewable free energy. We just had 24 x 250 watt panels put on the house. Boy was it fun initially (until the meter was changed) to see it running backwards most of the day. Now we just get credit for power fed back into the grid.

I can only speak of my own system.
I fitted 440 watts of Solar panels, through an MPPT controller driving a 4KW inverter via 3x 220 amp lead acid truck batteries (separate 150 starting battery)
I run a fridge and a freezer, immersion heater etc up to 4kw.
Obviously if the wife wants to use a hair dryer/iron etc turn off the immersion.
All imported from China and have had no problems and were completely independent during the summer.
Contact me if you need details for inverters etc.

By the way, what's an MPPT controller - what do the letters stand for, and how does it differ from the Sunguard controllers I have which are called PWM = pulse width modulated controllers..?

Peter B said:

By the way, what's an MPPT controller - what do the letters stand for, and how does it differ from the Sunguard controllers I have which are called PWM = pulse width modulated controllers..?

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This website covers MPPT better than I could, for sure. In simple terms they maximize amps into the battery bank, which is why you choose them.
What is Maximum Power Point Tracking (MPPT)

I installed 1820W of solar on the boat, 7 x 260W panels. The panels are nominal 30V, and go into two Outback FlexMax80 controllers. It was basically as much as I readily could fit. It was one of the reasons i Had a custom hardtop made to replace the bimini on the flybridge. I ditched an Onan 8kW and Mase 2.5 kW plumbed in diesel gennies, but carry a Honda eu2000 still, just in case....

Unfortunately I do not yet have any good data about performance on the hook as I have been downsizing houses and have rarely left the dock this year. But it should be pretty good. I recall that just after installation in Port Townsend I typically had 60A going into the batteries, and of course panels that are essentially horizontal are never going to get near nameplate capacity in such latitudes. Still, it is quite a useful charge rate. House bank is 1284 Ah of AGM's.

Comments above about getting high efficiency panels, opting for higher voltage ones where possible, providing an air gap under panels and avoiding shading (from antenna etc) if possible are all very important for good performance. In practice on a boat some panels will have shading, even if just a narrow strip from an antenna. It will have quite an impact, but most antennas can be lowered, and should be lowered if you really want maximum solar performance. Putting panels in parallel, along with MPPT controllers minimizes the consequences of partial shading.

Peter B said:

By the way, what's an MPPT controller - what do the letters stand for, and how does it differ from the Sunguard controllers I have which are called PWM = pulse width modulated controllers..?

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MPPT stands for Maximum Power Point Tracking. Panels are what's know in the electrical engineering world as a constant current device. That means that over a range of loads, they produce a constant current, and only the voltage drops/rises.

PWM does indeed mean Pulse Width Modulation.

Here's how each works:

PWM simply connects and disconnects (switches) the panels and the battery in such a way as to maintain a desired voltage. The amount of time that the panels are connected vs disconnected is considered the Pulse Width. By varying (Modulating) the pulse width, the controller regulates the voltage and hence the charging of the batteries. Make sense?

Getting back to panels and their constant current nature, a PWM controller basically operates the panels at the battery voltage. So if the panels generate 10A of current, and your battery voltage while charging is 14V, you will get 140W out of the panels. The issue is that panels are typically rated at higher voltages. In fact, every panel has a maximum power rating which is base on the highest operating voltage just before the current starts to collapse. This is referred to as the Maximum Power Point, and is achieved at the maximum power point voltage, know and Vmp (Voltage, maximum power). If you look at the spec sheets for any panel you will find all these numbers, and they are all based an a set of standard test conditions. Getting back to a PWM charger, it operates the panel at 14V where the panels Vmp is more likely around 20V. So a panel that is ideally able to produce 200W (20V x 10A) is only being harvested at 140W. The difference is the opportunity that an MPPT controller captures.

MPPT works a little differently than PWM, and is instead based on a variable DC to DC converter. It's called an MPPT controller because it operates the input to the DC-DC converter at the panels maximum power point, namely 20V in out example. So the input power to the DC-DC converter is the full 200W that the panel has to give. It then operates the converter output at the desired battery voltage, say 14V while charging. Well designed DC-DC converters are pretty efficient - around 90% or more, so 90% of the 200W input power is available at the output yielding 180W to charge the batteries. Compare that you the 140W we got from an PWM controller. That's a 28% increase in charging power. Pretty nice, right?

That's the basics, but there are a lot more smarts in an MPPT controller. It needs to "search" for the max power point on whatever combinations of panels you have attached, and it needs to find that max power point as the sun exposure varies over the course of the day, and as weather changes. This is where the "Tracking" part of MPPT comes from.

Hope that helps.

Oh, and I'd like to recommend the Alternative Energy Store (AltE: Solar Panels & Solar Energy Gear | Call 877-878-4060) as a good source for this sort of gear, including inverters and batteries. I have no financial affiliation, though they are friends of mine.

Thanks for that, Pete and Brian. Now I can be a bit better informed re solar power. Hopefully others benefitted as well.