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OJ
Master Marine Consultant

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USA
4382 Posts

Initially Posted - 07/08/2014 : 12:55:29

Used the search function, looked in tech tips and found very little discussion on solar panels. After doing a lot of reading elsewhere, I'm leaning toward a monocrystalline panel and MPPT controller.

Question: What wattage solar panel are people here using?

Edited by - OJ on 07/08/2014 12:59:24

islander
Master Marine Consultant

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USA
3992 Posts

Response Posted - 07/08/2014 : 15:57:47

The size of the panel depends on how much charging and the way you use your boat. For me I basically day sail so I have a 15 watt panel and a 7AMP controller. Between the engine and the panel my single group 31-105AHR's( A little bigger than a group 27) is fully charged and I don't need a battery charger. I run a GPS Chart Plotter, Depth sounder, Fresh water pump. Also at the end of the day we plug in a rechargeable radio and I-Pod. I rarely use lights but when I do It's only for an hour or so.

Edited by - on

britinusa
Web Editor

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USA
5404 Posts

Response Posted - 07/08/2014 : 18:12:59

We had an 18watt panel on my home built gimble mount. Typically got around .5 to 1.2amps(on really clear sunny days).

This past week I replaced it with a 50watt panel from amazon. Double the physical size of the 18w panel.

We saw 2.4amps at times over the weekend on the Bay!

The new panel is 50w at 17volts! So I did not expect 4amps at 12v.

Very pleased with the new panel.

Paul

Edited by - on

TakeFive
Master Marine Consultant

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2269 Posts

Response Posted - 07/08/2014 : 19:58:38

I read somewhere that the monocrystalline give greater power for a given size panel, but that they must be fully illuminated over the whole area, or you get nothing. Polycrystalline panels will deliver less power, but will deliver some if partially shaded.

This might be important if your boat's layout requires you to position the panel where it might be partially shaded.

Verify this with others, since my info might be incorrect or exaggerated.

Edited by - on

Tomas Kruska
Admiral

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Czech Republic
522 Posts

Response Posted - 07/09/2014 : 02:18:17

I use polycrystalline 51W panel and MPPT charger, all from Victron Energy. Plenty of power for compressor fridge, but it all dependents on many factors. I chose poly because of the size of the panel.
But definitely buy that MPPT charger, its much more efficient. I've also hooked my 9.8HP outboard charger coil to it, and it's able to charge around 4A when the motor is idle! (coil is rated 6A).
I just added one blocking Schottky's diode to the solar panel feed line (plus fuse on each power source, of course).

Edited by - on

Davy J
Master Marine Consultant

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USA
1511 Posts

Response Posted - 07/09/2014 : 03:54:24

My solar panel discussion:

http://www.catalina-capri-25s.org/forum/topic.asp?ARCHIVE=true& TOPIC_ID=22843& SearchTerms=new,toy

Mounting the panel so that it can be directed at the sun is a big improvement. One problem you might encounter is trying to find a solar panel that isn't too large or small. It seems most solar panels being produced now are either large, 100 watts+, or small, 20 watts or less. The panel that I have is no longer produced by Kyocera.

Edited by - on

glivs
Admiral

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USA
822 Posts

Response Posted - 07/09/2014 : 09:18:30

One of many good sources: [url="http://www.solar-electric.com/solarpanels.html/"]Northern Arizona Wind and Sun[/url]

I picked up a 30W panel on sale this winter from them...very pleased. Be sure to check the warranty on the different manufacturers..big differences.

Edited by - on

OLarryR
Master Marine Consultant

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USA
3367 Posts

Response Posted - 07/09/2014 : 09:43:53

I also bought my panel and controller from Northern Arizona Wind and Sun. I have a Kyocera 20 watt rigid panel. Believe it is a polycrystalline panel but it had at least at the time I bought it, it had the smallest footprint for a 20 watt - 14" x 20" and came with a 10 year warranty. The higher wattage Kyoceras come with a 20 year warranty. Rigid panels have far longer warranties compared to the flex panels but checking among the mfrs is still a good idea - Not that you will be returning a panel but kind of gives you a sense as to how well the panel will stand up thru the years and the confidence that the mfr has in theri panels. My panel will provide some charging if partially shaded. It has produced a max of 1.2 amps but averages between .6 - .8 amps depending on angle to the sun. When sizing a panel, best to not count on the max current the panel can produce - figure on 2/3 max and then depending on average number of sunny days per week (figure on ~6 sunny hrs per day for whatever nunber of days per week) and what loads you are likely to utilize on the average each week to get an idea of what size/capacity panel would be suitable.

I have a 15 amp Mornigstar Pro-15M controller with digital display. I believe it is a PWM controller.

My system has been hooked up since the fall of 2005 and for my light loads (Fishfinder, occasional use of nav lights and starting the outboard), my two batteries are maintained at full charge.

My website has more details on my setup.

Edited by - OLarryR on 07/10/2014 03:42:19

britinusa
Web Editor

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USA
5404 Posts

Response Posted - 07/09/2014 : 18:18:33

Larry, I have the same controller on JD.

However, I have the Load is connected to the power panel.

ie. the Battery is not directly connected to the distribution panel.

Paul

Edited by - on

OLarryR
Master Marine Consultant

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USA
3367 Posts

Response Posted - 07/10/2014 : 04:08:55

First, I noticed a mistake in my posting, which I have corrected. My controller is not rated at 15 watts it is rated at 15 amps.

Second, my photo for my controller is not completely accurate for my hookup at present. When I bought my boat in Fall 2005, it had 2 flooded batteries that were estimated to be about 1-2 years old. Those batteries were still fine after I used them for another 5 years but the standing voltage was starting to drop. I wound up replacing the batteries, sort of prematurely, due to already having a new Model 27 AGM battery that I had bought for potentially running my sump pump at home if electricity went out due to an imminent hurricane. Having averted that emergent need, I was left with a new AGM battery, so I decided to buy another one and replace my batteries on the boat. When I did that, I then decided to hook up the optional battery voltage sensing lines to the controller - That's the two addl battery terminals on the controller (see photo).

I would have to confirm exactly how I have the solar panel controller main charging terminals connected into my boat's wiring system since I have changed it around thru the years - In the beginning, I just had those leads plugged into a 12 volt DC accessory plug. But after the first year, it has been hooked up with the negative to one of the negative battery terminals and the positive lead from the controller to the old switch panel master circuit breaker - Basically means that the positive lead off the switch panel links into the battery switch. I normally leave my battery switch in the "Both" battery position.

I then have a 120 volt AC/DC charger that automatically kicks in when hooked up to dockside power and that has leads to independently charge each battery. The charging wires are hooked up to each battery directly. But I only use the dockside power if I am staying overnight at a marina and that is infrequent. At my marina, I decided to not pay the $20/month for electricity and so that is why I went the solar panel route.

Edited by - on

Voyager
Master Marine Consultant

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USA
5231 Posts

Response Posted - 07/10/2014 : 18:58:40

Similar story. I have an amorphous silicon 15W panel and a much smaller poly 20w panel with a 7A charge controller/regulator. I usually use the 15 Watter and lay it on the cockpit seat while Passage is on the dock when I'm away from the boat. When I get back to the boat, I put the panel away in the Q'berth. I only rarely use the 20 Watter esp when I need a major recharge (~2A).
In winter, I lay the amorphous panel on the bow and keep it in place with a tie-down. My Wal-Mart group 24 battery stays aboard both winter and summer. It's 5 or 6 years old and still charges fully to 12.8 VDC. I can still get about 25-30AH out of the battery while at anchor using an FM radio, VHF radio, USB phone charger, anchor light, cabin lights and my CPAP. Sooner or later the battery will wear out completely, but the solar panel, plus my 12A engine alternator, are sufficient to keep it healthy.

Edited by - Voyager on 07/10/2014 19:07:52

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 07/11/2014 : 12:10:38

Final selection:

RENOGY 30 watt
GENASUN MPPT, 5 amp

Naturally the 5 amp controller will allow us to go to a larger panel if our needs increase.

Thanks for everyone's input!

Mounting pix after installation.

Edited by - OJ on 07/11/2014 12:16:40

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 07/11/2014 : 12:21:54

quote:
Originally posted by Tomas Kruska

. . . Plenty of power for compressor fridge . . .

A solar panel can drive a compressor fridge? Interesting!

Edited by - on

Tomas Kruska
Admiral

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Czech Republic
522 Posts

Response Posted - 07/11/2014 : 14:10:43

quote:
Originally posted by OJ
A solar panel can drive a compressor fridge? Interesting!

Hehe... probably not during the night :-)

I meant it can charge up the battery when using the fridge.
I have Engel with 35W compressor, so that means aroud 2.9A at 30% of average running time. I have 51W solar panel giving 4A max so it's enough so far.

Edited by - on

HarlanBloomberg
Deckhand

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1 Posts

Response Posted - 10/25/2014 : 06:14:58

quote:
Originally posted by OJ

Used the search function, looked in tech tips and found very little discussion on solar panels using [URL="http://www.shinesolar.net/project-references"]solar energy[/URL]. After doing a lot of reading elsewhere, I'm leaning toward a monocrystalline panel and MPPT controller.

Question: What wattage solar panel are people here using?

Hello friend were you able to gather some vital details about these panels? I am looking to install them so is it worth to use them or not?

Edited by - HarlanBloomberg on 10/26/2014 22:11:49

awetmore
Master Marine Consultant

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USA
1144 Posts

Response Posted - 10/25/2014 : 09:00:35

quote:
Originally posted by britinusa

The new panel is 50w at 17volts! So I did not expect 4amps at 12v.

If you throw a MPPT controller on there you will get the 4 amps. They are efficient DC-DC converters and will drop the panel voltage. I often see 2.2->2.3 amps out of my 30 watt panel (which is also an 18v monocrystaline panel).

I had a 20w panel on my C25 and have a 30w panel on my Pearson 28-2, and both do the job very well. However if I were buying a new panel today I'd probably go for a 50w one. Then if I ever upgraded to a fridge I would add a second 50w panel and independent MPPT charge controller to get up to 8a of charging in good sun.

Genasun makes very good MPPT controllers that are affordable. This is the one for 50w panels:
http://genasun.com/all-products/solar-charge-controllers/for-lead/gv-4-pb-4a-solar-charge-controller/

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 10/27/2014 : 17:33:10

quote:
Originally posted by HarlanBloomberg

quote:
Originally posted by OJ

Used the search function, looked in tech tips and found very little discussion on solar panels using [URL="http://www.shinesolar.net/project-references"]solar energy[/URL]. After doing a lot of reading elsewhere, I'm leaning toward a monocrystalline panel and MPPT controller.

Question: What wattage solar panel are people here using?

Hello friend were you able to gather some vital details about these panels? I am looking to install them so is it worth to use them or not?

I didn't have the time (or patience) for calculating the correct size solar panel . . . so I decided to error slightly on the high side.

Go here: http://www.marinehowto.com/

and select: Installing A Small Marine Solar System

and you will see a mirror image of my system.

Edited by - OJ on 10/27/2014 17:34:48

Chief RA
Chief Technical Advisor

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USA
191 Posts

Response Posted - 11/03/2014 : 10:20:03

As many of our members know I just completed fitting out my boat this spring. After discussion with all, I think I got a good install. As far as our boats and solar use I opted for 2 ea 80w panels for my boat. With the 2.3cf Isotherm reefer drawing .7 amps avg per hr and other minor electronics charging the solar carried the boats DC system even during 4 days of overcast. I did find that using the DC TV and antenna amplifier maxed out the solar system if ran for hours. I opted to run the TV system from Marina power and not use it at all except in port. I am very satisfied with this system! Chief

Edited by - on

britinusa
Web Editor

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USA
5404 Posts

Response Posted - 11/03/2014 : 12:19:26

Chief, .7 amps avg per hour is a bit misleading.

I thought that unit drew 3.8 to 4.0 amps with the compressor running.

So when the unit is pulling 4amps at 12 volts, that would need 48Watts which your panels should easily handle.

Curious to see where you mounted the 2x80watt panels.

We have the Dometic cooler style Fridge Freezer and that pulls up to 4.7amps and the voltage takes a nose dive pretty quickly. Hence my overhaul of the electric system. There must be a resistance somewhere in the supply circuit.

On the upside, If I put half a dozen bottles of frozen water in the fridge, the compressor running time is much reduced. And I end up with some ice for my Rum on the Rocks.

Paul

Edited by - on

Chief RA
Chief Technical Advisor

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USA
191 Posts

Response Posted - 11/03/2014 : 14:10:20

Paul: You are quoting run amperage for your reefer wheras I am quoting an average per hour 24 hr demand. Your per hr avg will be at least 1/2 the work time of full time on amps. I mounted the panels across the stern on SS tubing with 2 ea 90 degree elbows and six worm clamps to the seat aft posts. Thay are high enough to use the ladder without hitting your head. This unit draws about 20 amps over a 24 hour period. Needless to say, I am very impressed with this unit! Bear in mind that it will go up some in hot weather but also I would have more sun/solar power. I was amazed when it ran for 4 days with virtually no sun! During the course of the night run on those bad days I never saw lower than 11.85v(reefer running, 12.15 not running). Granted we do not want to get down there much but it was lousy weather plus the panels would raise the voltage back up to around 12.6 to .8 with no sun and the reefer was never turned off. Your battery bank is also critical. I use 2 100AH batterys in my bank. We use zip lock bags for ice and it saves freezer room.
You should only be drawing around an Amp with your unit over average 24 hr timeframe and that is still good. Later, Chief

Edited by - Chief RA on 11/03/2014 14:21:21

britinusa
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USA
5404 Posts

Response Posted - 11/03/2014 : 18:42:15

Chief, it's the max current that I'm concerned about on our unit.

We only have 50watts at 17v, and typically see around 2-2.6 amps on a good day.

if the unit cannot run on that current, then it will draw from the batteries and that's my problem.

Pleased to hear your system works so well. We most often go out for 3 to 5 days, so need to keep the battery voltage up.

Any chance you can post pics of your panel mounts.

Paul

Edited by - on

TakeFive
Master Marine Consultant

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2269 Posts

Response Posted - 11/03/2014 : 19:57:17

quote:
Originally posted by Chief RA

...I was amazed when it ran for 4 days with virtually no sun! During the course of the night run on those bad days I never saw lower than 11.85v(reefer running, 12.15 not running)...

I'm not an expert at batteries, but I thought running below 12v would lower their lifetime pretty significantly. Are you sure you don't need to beef up your capacity?

Edited by - TakeFive on 11/03/2014 19:58:28

Chief RA
Chief Technical Advisor

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USA
191 Posts

Response Posted - 11/04/2014 : 13:01:08

Rick and Paul: I have tried to send an answer to you guys 4 times! I have been having satellite problems.
My battery monitor is so accurate that I read only 15/100ths below 12 and then only in one extreme condition. If needed I would just turn on my outboard to charge the bank for awhile.
Paul you need to get about the same solar system I have as you need about 40a/h a day to be sure you can handle your amps demand. Your reefer alone needs about 25 amps per day.
Better send this while I can! Chief

Edited by - on

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