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Old 10-01-2013, 12:09   #1
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Implementing solor panels - noob question

Hey all, forgive my noobishness but wanted to find out what this solar panels, batteries, electrical supply etc on a boat entails.

I used to work installing all sorts of electrical stuff in vehicles about 15 yrs ago. Back then when someone wanted a massive system we had to take into account the wattage and if the stock alternator provided the amps required or if they needed extra batteries or even stiffening capacitors etc.

Not even sure how to ask but can solar panels alone power typical boat equipment, lighting, radar/NAV, fridge/freezer etc? Are they used in conjunction with the engines to charge the batteries or (assuming there is sun out) can the panels keep the batteries charged to provide the power throughout the day.
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Old 10-01-2013, 12:17   #2
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Re: Implementing solor panels - noob question

Yes to your questions. Modern fridge/freezers are so efficient that 250 watts worth of solar panels and a decent housebank of batteries will do the trick. The other loads on a 24 hour basis take less, so under 500 watts of panels and you can swing on the hook for as long as you want. Should you want to go to a fully electric galley, you will have to up the ante on your solar panels and housebank of batteries, but that is the route I plan to go.
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Old 10-01-2013, 12:25   #3
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Re: Implementing solor panels - noob question

Yes, it can be done. You will need a controller to keep the panels from overcharging the batteries. The key is not only to have enough wattage to charge completely, but also to having efficient systems, such as using LED lights whenever possible.

The biggest mistake I see newbs making is not using wire of an adequate gage for the run, especially with 12v. systems.
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Old 10-01-2013, 12:26   #4
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Re: Implementing solor panels - noob question

I get 90-95% of my electrical power from solar.
I cruise all year around, usually with almost 365 days on the boat, so its certainly possible.

It does require a carefully set up boat, and some realistic expectations, but for me the quiet, reliable, free, heat free, green power is the best option, but your requirements may be different.

There are many options when supplying power to cruising boat. The trick is choose the best alternative, or combination of options that is most suitable for you and your cruising area.
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Old 10-01-2013, 12:27   #5
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Re: Implementing solor panels - noob question

There is a TON of information in the archives on solar and wind energy. Use the search function. It will take you a long time to read through the many threads and you'll find answers to most of your questions.

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Old 12-01-2013, 08:13   #6
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Re: Implementing solor panels - noob question

One thing to consider is boat size and what you want to do with it. Lot's of variables. The smaller the boat the fewer panels you can place so the less power.

I run a 15w (1.25 amp max) panel and my small motor give me 3amp (44w) of charging over half throttle. The only thing I have on my boat is led lighting, vhf, cellphones, gps. Served by 110AH in batteries. Of course I have a real nice AC charger for when we are on shore power, it helps to lower stress levels on long trips.
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Old 12-01-2013, 08:23   #7
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Re: Implementing solor panels - noob question

All of the above plus I favor having adequate battery sizes on board. Specifically, I find paired 6vdc golf carts the best option. Typically you will have over 200 ampere hour ratings for a pair needed to get 12vdc.

Sure, you can do the same with large heavier 12vdc batteries if you're still in your teens or participate in annual iron man contests. Remember, batteries also need to be removed at some point in time.

If you intend to use a skimpy 12vdc battery with refrigeration, you will soon be disappointed even with solar. Just my thoughts--

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Old 12-01-2013, 09:45   #8
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Re: Implementing solor panels - noob question

We have been without an alternator for 2 1/2 months and have lived exclusively on solar at anchor during that time (and it's winter now with short days and the sun low in the sky!).

We run two laptops for 8+ hours a day, watch a movie every night and listen to a few hours of music on the stereo. We have a DC fridge and DC freezer.

We decided to turn off the standalone freezer when the alternator quit, just to be on the safe side (new alternator arrives today, yay! ice cubes!!). The batteries are in float mode every afternoon between 1:00 and 3:00.

We have three 185 watt solar panels (24 volt), a Xantrex 60 amp charge controller and two inverters that came pre-installed from the factory (600 watt pure sine wave and 2500 watt modified sine wave inverter/charger). And a 640 amp-hour AGM battery bank.

Solar power supporting anchor-based living can definitely be done, but you do need a lot of watts if you want to live like you do in a house. The mast and boom frequently shade one or all of the panels. If a little shade falls on one panel it shuts down... So get more watts than you might need according to theoretical calculations...

My hubby was an electro-mechanical service engineer for his profession and he installed the wiring and components in one day. It was the 3rd solar power system he had installed on a moveable home (the two others were on a travel trailer and a fifth wheel trailer that were also used for full-time living off the grid). So he knew what he was doing, though the other systems also took no more than 3 days each.

We had our solar panel arch built in Ensenada, Mexico, by a fabulous steel fabricator, (Alejandro Ulloa who can be found through the Baja Naval boatyard). He mounted the panels as part of the job.
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Old 12-01-2013, 10:05   #9
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To the OP: the same rules still apply. A watt is a watt. Do a rough energy budget before you start and you'll be a lot happier with the final result.

FWIW in a northern climate we find 200 watts on our bus is largely decorative. I'm in the middle of a 750 watt install on Gray Hawk which I expect will significantly reduce our generator run time but won't eliminate it completely. The first step in a solar install should be to reduce electrical consumption wherever possible. Swapping in LED for incandescent lights will make a big difference.
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Old 12-01-2013, 10:12   #10
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Re: Implementing solor panels - noob question

I second the reduce demand first idea. LEDs are so much more efficient that all of the lights on at once use the same as one incandescent did.
I bought a book called something like Independent Power Generation or something like that, check online bookstores for something that applies to boats and RVs, it will be well worth the money as soon as you start buying stuff.
We started out with a cheap controller and it was next to worthless. We got a Blue Sky MPPT controller and it payed for it's self in fuel saved running the engine to charge the batteries.
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Old 12-01-2013, 10:14   #11
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Re: Implementing solor panels - noob question

Here is a good link for solar. The guy is very opinionated but seems to have solar power down. It has to do with RV's. He does it on the cheap. He also has a link to another guy who has a system with more bells and whistles. About Our Boondocking Life ę HandyBob's Blog I don't know anything about this stuff so can't verify his installation.
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