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sailboy26s 02-20-2013 09:43 PM

Soler Panel help how many watts?
 
Not sure i believe the salesman down at the RV store how many watts do i really need to top off my single battery in my McGregor 26s. Iíll use the battery to run a radio and lights at times. Hoping i can pick up a 30 watt panel to top off the battery within a day or 2? What size panel should i buy? I believe I just have like a regular car battery. Itís not a marina or deep cycle battery but I may upgrade to a deep cycle.

Thanks from Utah

fmueller 02-20-2013 09:53 PM

Re: Soler Panel help how many watts?
 
In the summer months in Utah, an unshaded solar panel mounted horizontally will generate an average about 5 W-hr per rated watt per day.

In other words, your 30 W panel, will give you about 150 w-hrs of energy. Is that enough to offset the load of the radio and the lights? well that depends on how long you want to run them for.

If the lights are not leds and are 50 W total. You'll get about 3 hours of use of the lights for every day of charging.

In practice, your solar panel is not likely to be totally unshaded all day long and there are some charge/discharge losses associated with battery charging so I'd probably count on about half that much on a typical day.

So if you sail once or twice a week and then leave the boat to charge the other 5 days, I think 30W will probably do it. If you sail more often, or run more loads, you might think about a 50 or 70 W panel instead.

hope that helps,

~Fortunat

mitiempo 02-20-2013 10:02 PM

Re: Soler Panel help how many watts?
 
A 30 watt panel will, with a basic controller which is needed, will only output about 2 amps at best, and that only on the good days. Figure 5 hours a day for useful output - 10 AH a day at best. If you have a group 24 battery it is about 75 - 85 AH. If you take it to 50% SOC you would have to replace say 40 AH. There are inefficiencies in charging - you need to put in about 11 AH for each 10 AH used. So a 30 watt panel will take 4 fully sunny days to recharge from 50%.

I would get a 50 watt panel and a good controller like the Morningstar Sunsaver or similar. That will get you closer to your 2 day goal and be better for the battery as well.

Lake Superior Sailor 02-20-2013 10:03 PM

Re: Soler Panel help how many watts?
 
Now all you have to do is find a place to put the panel where it will be safe!...Dale

mitiempo 02-20-2013 10:12 PM

Re: Soler Panel help how many watts?
 
A rail mount aft will solve most of the shadowing issues. The first picture in this excellent how-to link shows a good arrangement.
Installing A Small Marine Solar System Photo Gallery by Compass Marine at pbase.com

sailboy26s 02-20-2013 10:17 PM

Re: Soler Panel help how many watts?
 
Awesome info guys thank you very much!!!!:):):):)

sailboy26s 02-20-2013 10:22 PM

Re: Soler Panel help how many watts?
 
Quote:

Originally Posted by mitiempo (Post 992971)
A rail mount aft will solve most of the shadowing issues. The first picture in this excellent how-to link shows a good arrangement.
Installing A Small Marine Solar System Photo Gallery by Compass Marine at pbase.com

thanks for the pics, thatís what Iím thinking is off of the back railing there, i need to find some sweet brackets like they have there! i guess Iím going to learn how to weld SS =)

I just bought the boat last winter, i got all the bugs worked out last spring so just want to start adding to it. I need to get the electrical working better, relocate the battery, get the lights going, add a radio, this panel, fix my VHF radio and maybe add a depth finder =)
:)

mitiempo 02-20-2013 10:27 PM

Re: Soler Panel help how many watts?
 
Quote:

Originally Posted by sailboy26s (Post 992976)
thanks for the pics, thatís what Iím thinking is off of the back railing there, i need to find some sweet brackets like they have there! i guess Iím going to learn how to weld SS =)

There is not any welding necessary and the hardware needed is detailed in page 2 of the link here Installing A Small Marine Solar System Photo Gallery by Compass Marine at pbase.com
scroll down the page about halfway. The entire article is worth reading.

swampcreek 02-22-2013 08:58 AM

Re: Soler Panel help how many watts?
 
5 Attachment(s)
Definetly go with a deep cycle. I just posted on another discussion about what we did with the electrical system on our old Macgregor. BTW the PERFECT place to mount the solar panel is on a bracket and then on a stainless pole (You'll have to buy and cut to size) and then use the brackets for the mast crutch at the back, use a 2 prong through hull electrical plug and go though the engine well. I'll post my previous post here to maybe give you an idea of what we did. Also battery placement...In the V-berth I installed a large hinged hatch in there I placed and strapped down the batteries, the Perko switch was also in this location. I'll see if I still have the pictures of my modifications and post them here. The Macgregor is a FINE boat! We loved ours, we had so much fun with that boat but the 6 footitus bit into us so we sold her last Summer and bought our Catalina 320 shortly thereafter.

Here is the post I mentioned...

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

Back when we had our Macgregor I rigged up a 17" x 17" solar panel (Forgot the wattage) I purchased off ebay, wired it to a solar panel regulator and ran it to a set of bus bars (+ and -). The + bus bar then was connected to a Perko switch (OFF, 1, 2, BOTH). #1 battery was a series 27 deep cycle and #2 battery was a larger lawn equipment battery for back up. Our electical system was mainly for lights and the stereo, and a few 12VDC cigarette lighter type plugs for 12 volt accessories. The engine was a pull start 8HP Nissan that I installed an under the flywheel alternator on and ran to the bus bars. (I was VERY PROUD of this system which from stock was only a single toggle switch and a lawnmower battery). Although we carried an extension chord I only used it to run the vacuum cleaner and maybe once or twice to top off one of the batteries that was at the end of it's life cycle. This system worked fine for us but we didn't have refridgeration or any other large current needs. If your needs are minimal I'd try to convince the wife to try relying on DC as an experiment and if succussful ditch the AC altogether. I even had a reversable 12VDC computor muffin fan ($15 online computor store) mounted to a clam shell vent in the engine well that could run continuously to circulate the cabin air. A sweet system indeed!

swampcreek 02-22-2013 09:18 AM

Re: Soler Panel help how many watts?
 
4 Attachment(s)
More sots of our Mac...

Oh yeah, don't pay attention to what many say about the quality of Macgregors, most of it is pure recycled BS by people who have only heard this or that. I've been on MANY boats and there is nothing wrong with the quality of any of the Macgregors as long as they are used for their intended purpose of sailing in fairer weather, although we did push the envelope more than once including getting caught in some pretty serious weather, she did just fine. Boats are a lot like motorcycles, the machine can usually handle way more than the operator. If they had built a mid 30's boat I would have definitely put it on the short list when we were shopping.

BTW in the pictures you may notice that the forward bulkhead and head door is removed from the head compartment, that was removed for more space, I'm sure you know what I mean. That bulkhead is non-load bearing and can be removed. DO NOT remove the bulkhead at the sink! That IS load bearing and supports mast load (Pretty important).


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