Solar Panel Location

[cpost]

I was thinking of adding a solar panel to "trickle charge" the batteries when I'm away and was wondering if anyone has installed one under the window in the head. Seems like a good place if it gets enough light and would also keep it secure.

Also, any reccomendations on a good solar panel that is not too expensive?

[Buzz]

I bought some VW solar charger with suction cups off of ebay for 10-15 bucks and spliced on a cigarette plug and it works swimmingly. Battery is always full and don't care if it breaks. Something similar would cost $100. It does have a glass protector only down side.

[ronacarme]

Some of this I have posted earlier, but......
For several years I had in the cabin a 2 watt nonweatherproof solar plate for float charging the boat battery. Never did find a good way to mount it so laid it atop the fwd dinette seat back under the fwd window. Doubtful whether it did much good.
Replaced it with a weatherproof 5 watt solar plate swivel mounted outside, on a plastic pipe upstanding from the stbd aft pulpit, with zipcord led thru a silicone sealed hole in upper part of topsides at hull aft stbd quarter and under aft berth to boat battery. In direct sun, no shading by a window, easily adjustable to directly face sun, higher wattage panel.....much better. Plate stays mounted summer and winter, except is stored in cabin for road trips. As to cost, I think the plate was maybe $80-90 + shipping, the mounting being all inexpensive plastic pipe fittings from local ACE Hardware, modified as needed, < $10.
Recently bot a second 5 watt solar plate on sale at local Harbor Freight Tool store for $40 (to drive bilge fan).
Ron

[March]

It depends how large the panel is. Ours is a 65 W panel, mounted above the engine, on some special aluminum supports that a local craftsman fashioned. It charges the batteries all right--but we have a hefty consumer: a Waeco freezer/icebox that draws plenty.
Never ran out of juice though.
I am thinking about adding an additional flexible panel, either on top of the hatch, ot on top of the bimini. It should be at least 30 W, or the trickle would not be worth is--for my son's DVD player and laptop

[Night Sailor]

When I first went solar back in the 90s I bought a 11 watt UniSolar panel for the same purpose as you describe. It's still working fine while velcroed to the top of the main hatch. However, this is what I found: with a fully charged new battery, it will keep the charge on for all but the longest cloudy periods. IF you turn on the lights for a few minutes, or use the radio, or depth sounder or any other slight draw for more than a few minutes, it cannot replace the drawdown even on the sunniest days. It will take a week of sunny days. If you use major amps like starting a motor, running fans or other things for hours, it will not make it up no matter how long it is sunny, because lead acid batteries require a certain number of amps to fully charge which varies with type, size and age.

I now use it in combination with another 100 watts of high quality solar panels mounted on the stern arch and with low consumption of appliances, together with the amps from my Merc, they do a great job of making juice for my three Optima batteries.

[Catigale]

To put it in perspective a group 24 battery is roughly 1000 W hours of charge, so a 5 Watt solar panel like the VW one will replace 5 thousandths of your battery capacity per hour, or a whopping 5% in 10 hours of sunshine (assuming full rating which you wont get for 10 hours anyway)

It will just barely keep up with the slow 'leakage' of a lead acid battery charge with no load.

[Buzz]

Make two or three. Storage is not an issue with these because of the suction cups they can stick to the windows or the liner when not in use.

[Divecoz]

Its all about what are you looking to do. Are you needing just to know the motor will start when you return? It / they work for that, most often.
But if your actually trying to add back to a depleted system. . . No Way Jose. You need a Big $$ Solar system for that. You want to live on Solar? Land or Sea, Its your choice, Big bucks or drastically reduce your consumption.
That is what makes me crazy with the Green People. Wind nor solar works as an efficient means of production, on a major scale. Not yet!

[Divecoz]

Make two or three. Storage is not an issue with these because of the suction cups they can stick to the windows or the liner when not in use.

Buzz, unless all you want to do is start the motor you need to mount between 10 and 30 of those . . . .

[Buzz]

He asked for a trickle charge. Not starting motors.

[Divecoz]

He asked for a trickle charge. Not starting motors.

I 'm lost here a trickle charge is for keeping Batteries "topped Up" that is to prolong battery life and while doing that making available or possible the ability to Always be able to start your motor.
As we all know and depending on the needs of you and your crew and your boat, just starting the motor is not enough.
There would be no need for a Solar Source if 110 volts was available.
Most of these boats have a bilge pump ( mine has 2) Most have hard wire VHF, GPS Sonar, Fans , Numerous lights, music source.
So if your only ability is to keep a fully charged battery from going dead what do you really have ? IMHO nothing as you will never return with a fully charged battery after a weekend or maybe even after a day of using the boat. So imho you need to be able to recharge your battery.
I had a solar trickle charger for the battery of my VW bug in Cozumel.
It worked for quite awhile . It's function was to keep the battery from going dead in a zero use situation where we could depend on no less than 10 hours of direct sun per-day every day of the year. . . on average

[cpost]

Yes.. Trickle charge is what I want to do .. I've installed a am/fm CD player that has a direct connection to the battery to save memory/setup settings and also installed a dual battery monitor that pulls like 25ma in sleep mode .. so .. I'm just looking to have something supplement that very small drain on the system.. I think a 5watt should do the trick but I was really wondering if anyone has ever mounted one on the inside of the MAC 26M head window.. I know the window is tinted but wondered if the solar panel would still do the job if mounted there.

[ronacarme]

1. Window tint degraded output of my old 2 watt "interior" solar plate tho did not kill it entirely, given a direct rays from the sun thru the window onto the plate.....elimination of the tinted window avoids that degradation.
2. Most of the time, direct rays from sun thru window onto plate do not exist, e.g. window faces away from sun, sun rays are at acute angle to window face which reduces light thru window, sun thru window misses the plate, etc.....locating the plate outside the cabin and out of the shade of nearby objects, and aiming it to face the noonday sun, with boat position fixed (my X is slipped in summer), avoids those limitations. Actually the fixed, upward facing mounting of a similar 5 watt plate atop the lazerette hatch on my old D worked OK too.
Your 12 volt power use sounds about as low as mine....LED cabin lights at night, small FM/CDplayer, rare VHF radio use. Motor starting and rare running light drain on the battery is made up by the small alternator on the motor. So my 5 watt plate is primarily to trickle maintain the battery.
As you can see I prefer the plate outside.
Ron

[walt]

If you look at solar for real time power, you should listen to the people who poop on it.

However if you occasionally use your boat, it is really great. I have a 20 watt panel permanently mounted on the boat, have car stereo/Ipod,DVD player, cabin lights, VHF, GPS, depth finder (note, there is nothing in the list which consumes a LOT of power). Last year, I sailed over 22 days mostly on weekend but also including a 4 day trip and never once spent a second charging my batteries. I didnt even have the outboard charger hooked up. Everytime I used the boat, everything was either fully charged or close enough. Ie, pretty much zero hassle. I have had to mess with charging the batteries one time this winter while working on the boat but that is because the panel is mounted flat and the place where the boat is stored gets only few hours of sunlight, snow on the panel ect. But during the summer, its pretty much hassle and maintenence free. In my opinion Solar is really about no hassle if you only occasionally use the boat. For extended cruising, solar might not be the ticket unless you have a lot of panel area.

This web site has the best search and archive of any of the Mac related sites and you can likely find lots of postings on how to figure things out (no need to repeat here) since you have to be more concerned about power manegement.

[johnnyonspot]

Assuming the motor has an alternator and charges the battery while running, why would a trickle charge be insufficient to keep the battery topped off while not using the boat?

As far as the solar panel doing its job behind a tinted window, I am no expert but guess this will not come even close to working. Why not just stick it on a cockpit seat while not using the boat and plug it into a cockpit cigarette lighter socket? You could even put it on the cockpit sole to keep it out of sight of those with sticky fingers. Only under the absolute best of circumstances, in direct sunlight shining straight down, perpendicular to the panel do these things approach or reach their rated capacity. So unless you have it mounted on some mechanism that follows the sun, it needs to be facing 12 O'clock high to maximize exposure and thus output.