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solar panel question

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tom
1st Mate

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USA
52 Posts

Initially Posted - 11/20/2002 : 19:09:25

I just purchased the 3 amp solar panel from catalina direct. My boat
has a honda 9.9 that does charge the battery (not much because it's
hardly ever on). My question is... can I install the Solar Panel and still use the charging from the engine? And What happen say during the
middle of the week when the batteries are full? Do the batteries
refuse more charging or do I have a problem. If anyone has this solar
unit where did you mount it. I was thinking on the stern pulpit away from everything. Any suggestions.

Edited by - on

IndyJim
Navigator

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USA
130 Posts

Response Posted - 11/20/2002 : 22:54:54

Tom,
I'm sure you'll get a lot of better and maybe more sensible answers from sailors with more time at the helm but here's what I did. You can, of course take it or leave it.

My C-25 spends most of the summer on a buoy and thus the shore power plug and Guest battery charger doesn't do me much good. And, like you, I don't run my motor much because I can unhook and sail off the buoy.

So, if memory serves me correctly, I purchased a 5 watt flexible solar panel from West Marine. I've got quite a few items onboard that draw current so I wanted to keep the batteries topped off. Since I don't come aboard until early evening after work, I thought it would be fantastic to have the batteries charging while I wasn't there.

Like you, I needed a place to put it. After much consideration, I purchased some snap fasteners (similar to velcro but no fuzzies and MUCH stronger locking) and mounted on the foredeck between the mast and the forward hatch. That area never seems to get traffic because I have my halyards ran aft. In my sailing situation, it was a perfect location for my needs. I mounted the power plug near the plug for my mast lights and ran the wires back to the electrical panel and to a three way switch. The switch allows me to select which batter is getting the solar charge.

I'm not an electrician by any means. But this worked superbly all summer long. I never had to pull a battery to put on a charger and believe me, I have lots of accessories, lights and an autopilot.

So, I'm a beliver. If I had a slip with shore power this innovation would not have been necessary. But I really like the solar panel. The only thing I might do is get a larger one. I think they make an 11 watt flexible one that would be nice.

The one thing I've learned from this great website is.... there are no wrong answers. Only the one that works best for your situation. Now I'll sit back and hear how others tackle the problem and probably feel foolish.

Good luck!

IndyJim
"Itza Dew Sea"
'84 SK/TR #8425

Edited by - on

Mark Loyacano
Navigator

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USA
247 Posts

Response Posted - 11/20/2002 : 23:09:02

Thanks IndyJim.
Question: Does a solar charger need a regulator or is 5 watts constant charge too low to damage anything?
Thanks,
Mark L.
C25 #549, SK/SR

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 11/20/2002 : 23:24:59

Mark,

This is from the West Marine Advisor,

Solar Panels

What they do

Solar panels convert the sun's radiation (light) directly into electricity, which can be used to charge batteries and operate DC loads. There are several applications for solar energy on boats.

Maintenance charging for boats on moorings.
Augmenting engine-based charging on cruising boats.
Sole-source charging for boats without auxiliary engines.

How they work

Energy from the sun's light strikes the solar panel crystals knocking some electrons loose and creating electricity. (OK, that is a little brief, but to the point.) Each solar cell in a panel creates a potential of about 0.45 volts. To create sufficient voltage to charge a 12-volt battery, 30-36 cells are connected in series to produce from 14 to 17 volts. Amperage (current) is proportional to the area of each cell: larger cells produce more current. 3" cells = 2 amps, 4" cells = 3.1 amps, 5" cells = 5 amps.

There are three main types of solar panels: Monocrystalline (Siemens), Polycrystalline, and Thin Film (United Solar).
Monocrystalline panels have uniform dark grey or black cells and have the highest output per area. They tend to be the most expensive as well. Polycrystalline cells look somewhat like shattered black glass, and are less expensive as well as less efficient. Both types are inflexible. Thin Film panels are flexible and about 50% as efficient as monocrystalline.

How much output can I expect?

Our design rule is that a solar panel will contribute as much as half of its wattage, in amp-hours, each day if aimed at the sun and perhaps 25% if randomly oriented. This means that a 48-watt panel will contribute as much as 24 amp-hours per day if aimed at the sun and perhaps 12 amp-hours if randomly oriented.

Do solar panels require regulation?

As a general design rule, panels that produce less than 1%-2% of the battery's capacity in Ah don't require regulation. This means that a 2-amp panel is the largest you should use without a regulator on a 100-amp-hour battery. Regulators should be used almost anytime you have two or more large panels connected to your batteries. The regulator will shut off the panels when the battery's charge exceeds 14.3 volts.

If you are operating your boat with batteries that are seldom fully charged, as is the case when cruising, the chance of over-charging them is much less. Remember, your solar panels will "turn off" every night and during cloudy days. This ensures your batteries are not held continuously at an elevated voltage, but they may exceed a healthy voltage in the afternoon sun.

Self-regulating panels produce less voltage (fewer cells), and theoretically will not overcharge your batteries. Frankly, we don't think this is the right solution. We would rather use higher voltage panels with regulators, or smaller panels which are incapable of overcharging. Self-regulating panels are much less effective in high temperatures, since their voltage can drop too low to be effective in charging.

Here's the link.
http://www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorDisplayView?advisor=478.htm

Don Lucier, 'North Star'
C25 SR/FK
Lake Erie

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2984 Posts

Response Posted - 11/20/2002 : 23:26:16

If the solar panel has the aluminum frame... one idea to make it more friendly to the boat is to protect the corners. This can be done by using old tennis balls by making an H patern cut in the ball with the sides of the H the width of the frame.

Open the tabs made by the cuts and slide the balls onto the corners. Drill and pop rivet the tabs onto the frame.

The tennis ball feet will now sit across the cockpit seats or on top of the companionway hatch without doing damage.

Arlyn C-250 W/B #224

Edited by - on

WGriswold
Deckhand

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USA
23 Posts

Response Posted - 11/21/2002 : 18:14:33

I have had a 5 watt (0.4 amp) solar panel on my boat for fifteen years without a regulator and have had no problems. If I were to switch to a 36 watt (3 amp) panel I would definitely install a regulator. You should consider a diode to prevent the current from flowing back to the panel at night. I think I have one, but I've never checked. It works fine so I have no reason to tear into the wiring. The 5 watt panel is mounted vertically on the inside of the transom and even with that poor orientation to the sun it keeps the battery charged unless I use the boat for four or five consecutive days.

Wait Griswold
C25, 1986, sk
South Lake Tahoe

Edited by - on

John G-
Admiral

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793 Posts

Response Posted - 11/21/2002 : 18:41:02

I wrote the following question to Uni-Solor.

“My boat has 2 batteries with an "A" "BOTH & "B" switch. How do I hook-up the flexible panel to charge both batteries and is the 11-watt enough for weekend use? Do I need a splitter for the positive wire and do you supply it as an accessory? Thank you.”

Here is the reply. The typos are Uni-Solar’s.

“The answer to you question is... very carefully. You want to avoid to break the isolation between by bypassing your switch. So there are tow (two) ways you could do it. You could add another "A-B" type switch to the solar modules, or you could connect the solar panel to one battery only.

If you connect (i.e. split) the solar modules directly to both battery(s), will the short the batteries through the solar panel wiring. If there is a big difference in charge (i.e. one is full and the other is discharged) I could create rather large electrical current, thus potentially causing a multitude of problems.

As for the 11W module, you need to be a bit more specific about your intended use. If you are going to use it in the NY area, then during the summer (6h peak sunlight) the module will produce about 22 Ahr per week. So if you only have a light use of your system, then it is probably enough. Marine use tend to use the 32W modules, which produces about 10Ahr per day. So, essentially, a 32W panel can give you the use of a car battery for the weekend (70Ah), which is probably closer to how such a system is used.

To maximize the efficiency of you system I strongly recommend the use of a small charge controller (probably a 3A or bigger). A charge controller will definitely squeeze the maximum power out of any solar module. I controller that I like to use/recommend is the SunGuard 4 from Morningstar. It is the size of a golf ball and retails for about 30$ and is probably the best out there.

If you let me know more details about the use of your batteries, I will be more than happy to size up a system for you.

Hope I answered all you questions... Feel free to contact me if you have any other questions."
Regards,

Luc Collin
Applications Marketing Engineer
Residential and Consumer Application

Bekaert ECD Solar Systems, LLC
3800 Lapeer Road
Auburn Hills, MI 48326 USA
Tel: 248.475.0100
Fax: 248.364.0510
Web Site: www.UNI-SOLAR.com

 

[url="http://www.peregrinefund.org/"]<img src="http://www.peregrinefund.org/images/intro_mid_image.GIF" border=0>[/url]
 John G- "PEREGRINE" C25-#4762 FK

Edited by - on

aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 11/21/2002 : 19:46:26

Gents,
I also keep my boat on a mooring and am required to maintain an anchor light. To keep my batteries from discharging overnight I purchased a Davis "mini-amp" anchor light from West Marine. The battery lasts all summer with only an occasional charge from the motor - 2 1/2 hours out to Lake Superior and back per month.

To suppliment the low-amp light I have also purchased, but not yet installed, a Siemans 10 amp solar charger. It comes complete with 15' of wiring and an in-line regulator. A real nice kit on a rigid frame. I plan on mounting it on the stern pulpit using PVC conduit and various nylon fittings used to install bimini frames. I've used these in the past on other applications and they work well on pulpit tubing.

I have seen wiring diagrams where the panel charge wire is led into the 3-way battery switch, allowing you to select which battery to charge. Does anyone know if this will work?? Right now I'm planning on attaching the panel to my "house" battery only.

Al
GALLIVANT #5801

Edited by - on

kurt
1st Mate

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27 Posts

Response Posted - 11/25/2002 : 09:13:01

I have a flexible 13 watt panel with a 7 amp regulator that charges the two batteries. My boat is on a mooring, the batteries are always at the top when I arrive for the weekend. I never have to worry about overcharging if I can't show up for a couple of weeks. I wired the regulator to the back of the battery switch. It has been working great.

Kurt
86 SR/FK
“Snowfish”

link to photo www.snowfish.org/boat/vent.jpg
<img src="www.snowfish.org/boat/vent.jpg" border=0>

Edited by - kurt on 11/25/2002 09:35:12

Edited by - kurt on 11/25/2002 09:36:52

Edited by - kurt on 11/25/2002 09:38:14

Edited by - on

Doug C.
Navigator

Members Avatar

USA
146 Posts

Response Posted - 11/25/2002 : 19:19:59

I have a 5 watt panel and two group 24 batteries. I wanted to be able to charge both with the motor and the panel. From an inquiry over at the trailersailer site I got a suggestion that seems to work well. I use an automotive type battery isolator, the one with 3 terminals. I only use two of the terminals though.

The positive lead from the solar panel and the motor go to the center terminal, from the center terminal I ran a cable to my #2 battery which I use primarily as my motor starting battery. This allows the motor and the panel to charge battery #2 and allows the motor to draw from battery #2 for starting.
I connected a cable from battery #1 to one of the isolated terminals on the battery isolator, this allows battery #1 to be charged with both the motor and the panel but the motor cannot draw from #1 for starting.
All negative cables are tied together and connected to both batteries.

This is working well so far and as an added benefit I can charge both batteries by pluging the charger into the motor connector on the transom. I don't have a built in charger.

It is a bit of cabling but I gain lots of flexibility on load routing if needed.

Doug

Doug Cavin
1990 C25 TR/WK #6010
"Valkyrie"

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