Solar Power

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fizerocks

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Question for anyone that has installed solar panels on their boat. We have a 1998 290 Larson on the Mississippi River. Our typical boating weekend involves leaving the slip on Friday and not return to the slip until sometime on Sunday. While we do have a generator to keep batteries charged and for making coffee I would like to move away from having to run the gen only on rare occasions.

Our biggest battery draws are the refrigerator and 12 volt fans we run at night if the breeze is minimal. With three persons and two small dogs the cabin can get a little stuffy. Also, since we live three hours from our boat we also utilize a 12v Igloo plug in cooler for transporting our weekend food supply. Since we have the 120v adapter we can keep this plugged in at home and add items to it as we prepare them during the week. Once we are at the boat we load up the boat frig and anything that didn't fit placed on the ice coolers. This past weekend we decided to freeze a couple of water jugs and keep them in the Igloo with the food items which worked out well when we were anchored. Anytime we were running I had the 12 volt cord plugged in and when we ran the gen on Saturday night for a bit I plugged in the 120v cord. Again this worked well and the jugs stayed frozen pretty much the whole time with no food spoilage issues. However with how well this worked out it got me thinking about the ability to install a separate battery bank to run the Igloo, fans, existing boat frig and convert to a 12 cup 12v coffee maker with the ability to charge this bank using solar power.

From Northern Tool and Equipment I can pick up a 15 watt solar panel which would mount on the top of my radar arch. I would also install the charge controller to keep prevent from overcharging the battery. My thought is to install separate 12v receptables in the cabin and rewire the frig to the new bank.

So I guess my question or feedback I'm looking for is does this sound possible, a good idea, is there a better way of doing this? Really just any feedback anyone who has done solar can provide would help.

Thanks - James
 
Yes it IS possible BUT first you have to do the math.

Figure out what your daily load is, then figure out how long you have to charge the battery and what kind of power it's going to take to do that over that time frame. If you want enough solar to keep your batteries up while you are using the boat, it's going to get expensive.

A fridge will probably draw 100 amp hrs (or more) in a 24 hr day. I don't think shutting it off at night is that much of a savings.

Fans: Say 2A per fan x 8 hrs, 16 amp hrs per fan. Two of them and you have 32 amp hrs. So we're up to 132 amp hours per day already; Times 12v and you have nearly 1600 watt hrs. It will take that 15 watt solar panel over 100 hrs to recharge the battery assuming everything is OFF and there are no drains.

If you want the solar panels to carry the full load continuously you'll need 1600 watt hrs / 4 hrs per day or 400 watts (rated) of solar panels. That'll cost you $2000 or more, and where are you going to put 40 sq ft of solar panels? Yes I know you have more than 4 hrs of daylight but the panels are only effective part of the day and rarely put out full rated power. Here in Florida I get about 6 hrs/day. I have a 600 watt array and it will run everything on the boat except the water heater, stove, and air conditioning. It probably cost me over $3k.

If you're a weekender I'd figure out what size battery bank I needed to carry the weekend (again, do the math), and simply recharge it off shore power during the week. It's a whole lot less expensive.
 
Steamboat hit it pretty squarely on the head. You'd be better off running the genny to charge a larger battery bacnk with a bigger charger.
 
So if I were to just do the Igloo frig which states it only draws 6amps if I have a 100ah battery does this mean I could run it roughly about 15 hours before the battery is completely drained? If I had a single 15 watt solar charger would this not be adeqtare to keep the battery charged enough so I can run the cooler an entire weekend?
 
no... you can only use up to 50% of the battery capacity (assuming true deep cycle_), so if you have a 100AH battery, that gives you about 50AH usable or about 8 hours.

now, keep in mind your fridge/cooler may be cycling on and off once it's cold, which will obviously extend how long the batteries will last. if you go that way, monitor the voltage to turn it off when you reach 50% discahrge (forgot what voltage it is on a 12v system... probably around 11.5v, measured with no load).

Solar is great but it hard to make the numbers add up .
 
NO!

If you drain your battery completely each time it won't be long before you are buying a new battery. Rule of thumb is 50% for good battery life, so you'll get about 8 hrs use on that battery. That's 48 amp hrs.

You are mixing watts vs amps. Your 15 watt solar panel will only put out about 1.25 amps in bright sunlight. (15w/12v=1.25a). So it'll take that panel at least 48ah/1.25a=38 hrs (in bright sunlight) to recharge them (probably about a week). If the Igloo is still connected it'll draw more than the panel can put out, and your battery will still go completely dead.
 
speaking of solar and mxiing Amps and Watts there is an article in Power & Motoryacht this month about a new Fleming equipped with a large solar array on the hardtop. Lots of bragging and drooling about the Green technology and being responsible and coming up with new ways to save the planet.

as usual with these glossy rags, the article doens't answer the basic question anyone with the IQ of a 5 year old will have: will the panels be able to recharge the batteries the day after a night on the hook without running the generator or the mains? The article goes on to explain how wonderful it is to be able to turn off the genny at night and be on a quiet boat. Great... how the batteries and inverter keep the sub zeroes and ice makers and lights running. but no word on what happens the next day...

The author conveniently fuzzy up the math saying that the "total output is 1500W, which is well over that the 1400Watts the boat uses underway". Then further, they mentionned that they never got the full 175Watts out each panel, only 125... they mix up Watts and Amps and Volts...

no wonder these magazines usually stick to reviewing drink holders and fabric colors...
 
Another great reason for Boatered. Thanks guys for all the input.
 
You need large panels I have 2 120 watt panela and a 180 watt panel that feed a MorningStar PWM 3 stage controller/charger. I am not entirely impressed. I will report my actual numbers after this weekend because the entire Spring here on the East Coast has been cloudy and raining when ever I am down at the boat. Last week I re-set the total AH's so I can tell you real world what AH's were put into the batteries or shed.
Bill
 
Good clean math Willie. So far my system has not performed as advertised. I have not skimped anywhere. The panels are top quality Kyocera and so is the charging system. I even wired it into my Link2000 controller as an aternative charging source so it adds the dockside/generator or solar Amp hours and % of charge. I have also replaced most equipment, fans and lights with the latest low current draw devices available. I even just replaced my fans because (if forget the name) a popular boat fan manufacture came out with a good volume 3 speed fan that only draws 2/10ths of an amp at full speed. Bill
 
"I can pick up a 15 watt solar panel"

I like the idea of solar. But it is nowhere near the panacea that we all wish it were. 15 watts "ain't diddly". That particular panel would likely provide only a daily total of about 150 watts. Or measured another way, it would only replace around 12A of your battery's charge. And that performance should be considered optimum performance. Those beautiful fluffy white clouds will cut performance. I would count on 10A/day or so, average ( or less ). And one ( 1 ) fan might easily draw 1A every hour... OR a 5 watt cabin light will draw 0.5 A every hour. Stored electricity onboard is a very valuable, and rare commodity.

btw: I would add solar to my boat, but my "minimum" size panel would be in the neighborhood of 150 watts ( 10x larger than the one being discussed ), which might actually make an impact on the boats electric system. There are also misunderstood datasheets, inaccurate data, charging inefficiencies to be considered. And the level of competence of reporters on this subject is incomprehensible.

Imho, a 15 watt panel might be useful for keeping the batteries topped off ( under no-load ) while I am away, but I would not consider it to be a contributor to the systems "charging capacity".
 
I've used a 40-watt solar panel plugged into the cig lighter adapter to maintain one boat battery at a time. It worked well for that, but it sure wouldn't work well to run a frig, etc.

Bill said, "a popular boat fan manufacture came out with a good volume 3 speed fan that only draws 2/10ths of an amp at full speed."
can you get me the name of the manufacture? Right now, I only use the one I have while I'm underway....

Thanks!
 
We go through this several time a year... but a little refresher might be useful.

You need to calculate just what your usage truly is. It is simple, but tedious. Make no assumptions, do your best to discover exactly what your usage is, how it fluctuates, and who are the "big eaters".

Once you have a solid handle on how much you will consume daily, you can plan a system to provide for your needs.

You need to store it. Rate your batteries at 50% ( I'll skip the gory details, for now ). And for various tech reasons, rate the voltage at 10v for these calcs, this covers a bunch of inefficiencies and makes the math easier.

Let us assume that your daily consumption is 2000 watts. This requires 200A storage ( and about 250A charging ) You can provide 200A of storage with four ( 4 ) 12v type 31 deep cycle wet cell batteries.

Now let us consider that you will need to charge those batteries every day, which will take about 250 A to do the job. Using solar, I will assume 5 "sun hours" so your panels need to provide 50 amps per hour of sunshine. Panels are over rated, since they use peak open circuit voltage, times the max current possible. So de-rate the panel by 30% to cover the mis-labeling, which gives about 71A or using mfgr stated output, 850 watts of solar panels, or about twice what BIllyIII describes for his boat. Roughly four 210 w solar panels needed to provide a 2000w "off-grid" system.

I hope you find this generalization useful...
 
Bill you are correct my house bank is 765AH so half of that is usable or 382.5 usable AH's from the battery bank. I find the solar suppliments the house bank just extending recharge times. I am not able to place the controller in power supply mode and run all my electronics at peak sun so that says something in itself. I put the panels in again as a supplimental charging system to extend recharge times. It also helps because I only have 2 60 amp alternaters when cruising (the new Mercruisers have a tiny alternater). Now it does just fine when I leave the boat for 3 to 5 days keeping up with the basics left on and keeping the house bank topped off. In other words if my boat was at a mooring I have more than enough capacity when the boat sits idle to run the bilge pumps, alarm system and a cellular modem and keep the house bank and 1 starting bank fully charged. In fact the longer the boat sits the system actually goes into maintain mode or trickle charge. Bill
 
I don't understand why there are so many 15 watt and smaller panels sold. I guess if you had a small boat and no dock power it could help keep a group 24 battery charged? In my opinion barely. Hopefully Yzer will chime in he does very well using solar panels and ice chests for extended cruising or anchoring out. My boat unlike his has an electric head, large DC water pump and watermaker and a 7 cubic foot DC frig that draws 2.8 amps when on and it runs at least 70% 0f the time. Doing a boat electrical link budget is very important when sizing the house bank, your dockside charger and properly sizing a solar array. Myself I amj out of room unless I put an aft roof above my cockpit I really have no more room for the additional panels I would need. I already have added enough wieght to my boat so the aft top and enclosure are not going to happen.
Bill
 
yzer posted this ( last year??? ) and I saved it because he stated it so nicely. Note: this is yzer's work, not mine...

----------------------------

Decide on what you want to do with the boat and how solar power can contribute to its operation. While doing the initial restoration of the boat I had plenty of time to stand back and make a big-picture evaluation of how I wanted to use the boat. You may want to use solar power to trickle charge the boat while you are away during the week. I wanted a solar power system that would replace the power I used at anchor on a daily basis.

Think about the power you want in terms of amp/hours. Compared to a genset, the amount of power produced by a solar power system is pretty limited. I don’t know of many boaters who power a boat with air conditioning by solar. However, I know of several boaters who do power a refrigerator and the rest of the boat by solar.

Think of a solar power system in three parts: solar power storage (batteries), solar power collectors (solar panels) and the solar power controller (charger).

Batteries: This determines how much 12-volt power you can store on the boat. There are many choices: there are wet cell standard 12-volt batteries (starter batteries or deep-cycle), 6-volt golf cart batteries, 12-volt AGMs, dual purpose batteries, etc.

Panels: There are two basic kinds for marine use: rigid panels and flexible panels. Rigid panels feature the familiar glass and metal construction you see on home solar installations. These are modified for use on a boat. Rigid panels offer the best output power. Flexible panels provide less power output but offer serious installation advantages for smaller boats. Flexible panels offer lighter weight and can be strapped or tied onto the boat as needed.

Charge controllers: There is a basic rule of thumb: you will need to use a charge controller if your panels can produce 1.5% or more of your battery capacity in amps. For a 90 amp/hr battery, that's 1.4 amps or more. If you want a solar power system to trickle charge and maintain batteries over period of time you can get by with less than that 1.5% and not use a charge controller. If your solar system produces more than that 1.5% you run the chance of destroying the battery without a charge controller. A good charge controller with PWM charging will work like a good three-stage AC-powered battery charger and extend the lifespan of your battery.

An individual solution for every boater and each boat: For my boat, I decided to use the least amount of 12-VDC power I could get away with. Our boat has three group-27 deep-cycle batteries. To maximize the lifespan of these batteries, I never discharge them to less than 50% of the rated 90 amp/hr capacity. I figured a daily power usage of about 30 amp/hrs per day while at anchor. By modern boating standards, that’s almost nothing.

Two of the batteries are house batteries. While at anchor, I use one house battery for one day while the other is fully solar charged.

I installed low power lighting wherever possible. LEDs provide courtesy lighting so that I can get around the boat at night.

I hard-wired a Davis Mega-Light as a low draw anchor light. There are now LED anchor lights that will work just as well.

I replaced the household style 40-watt 12-VCD incandescent bulbs on the boat (common on old boats) with 12-Volt compact fluorescent bulbs that consume just 13 watts at 12-VDC, but produce the same amount of light as a 60-watt incandescent bulb (FEIT BPESL13T/MAR-12). These are getting hard to find right now: http://www.blacklight.com/items/BPESL13TMAR12V

There is no waste holding tank on the old boat, so I installed one of the lowest-power Type I sanitation devices available: a Purasan Type I system by Raritan. Use of this system is EPA and USCG approved in my area.

No power-consuming refrigerators for me. I figure that a refrigerator requires at least 90 amp/hrs per day in my part of the country. Two six-day Igloo coolers with block ice work fine for six days on our boat: even with opening and closing and 90-104 degree heat during the summer. During our summers, covering the ice chests with wet white towels is a must.

Other power-saving necessities include an oil lamp for extra illumination and a non-pressurized alcohol stove.

Even with power usage limited to 30 amp/hrs per day, we still get to run the VHF radio, run battery-powered entertainment devices of all kinds, charge cell phones, read all we want day or night, watch TV, listen to CDs or catch a DVD during mosquito time.

I bought the solar panels four years ago and chose two Uni-Solar FLX-32 flexible panels. These panels features heavy-duty construction and weigh five pounds apiece. During northern California summers, this is about 64 watts total output or 30 amp/hrs of solar power per day. These panels tie onto the cockpit canvas of our boat. Because solar panels are a desirable target for thieves, I tie the panels to the canvas prior to making multi-day outings. It takes only ten minutes to install and hook up the flexible panels. I roll the panels into a one-foot diameter cylinder and store them safely after returning to the slip. Unfortunately, Uni-Solar discontinued production of these panels to concentrate on solar roof shingle production.

I helped in planning solar power installation for my in-laws last summer: again, using canvas-mounted flexible panels. For their 40-foot boat, I chose Global Solar GSE P3-55w panels in black. These can be folded and stored easily.

Compared to my older Uni-Solar panels, the GSEs offer nearly twice the power output for size and weigh less than two pounds apiece. Technology in this field is advancing every year. Note that due to high demand from the US armed services, the GSE P3 panel series may not be currently available. However, the GSE SL Sunlinq series is still available for non-service related purchase.

I like Morningstar charge controllers. http://www.morningstarcorp.com/ Morningstar offers a wide variety of charge controller models. SunSaver 10 is an easy to use 10-amp PWM charge controller. Rated for explosive environments, it features a temperature sensor built into the unit. This small controller is mounted close to the battery bank. A green LED indicator light tells you the system is working: if you don’t believe it you can use a 12-VDC multimeter to run the tests.

The best part about solar power on a boat is the quiet. And the look on another skipper’s face when he sees you start your engine on the first crank after he’s watched you sit at anchor for nearly a week without running any motors.
 
quote:
Originally posted by Flutterby

I've used a 40-watt solar panel plugged into the cig lighter adapter to maintain one boat battery at a time. It worked well for that, but it sure wouldn't work well to run a frig, etc.

Bill said, "a popular boat fan manufacture came out with a good volume 3 speed fan that only draws 2/10ths of an amp at full speed."
can you get me the name of the manufacture? Right now, I only use the one I have while I'm underway....

Thanks!

Click to expand...
The new Caframa Sirroco 3 speed 12 volt fans on low it draws .1amp medium .2amps and .25amps on high. The model is 807CAW8X.
Bill
 
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