Solar Panels - Looks Like a Good Buy

P

Pat Anderson

New member
Joined
Nov 2, 2003
Messages
8,562
Reaction score
0
C Dory Year
2005
C Dory Model
25 Cruiser
Vessel Name
Daydream
These 15 watt Brunton SolarFlats are $180 on the Brunton site, $99 sale priced at C&C Outdoors...anybody used them? They look like just the ticket to me!
 
If you're interested in solar panels, here's a site that lists the cheapest panels, daily. Just watch out for Chinese panels, they don't have a good rep (yet.) $4 per watt is a good price.

Solar Panels

It worked for me, I just got 2.5 Kw.The site mainly lists large panels (200 watts,) but if you look at some of the referenced sites, they also have smaller ones. Note the string output voltage, since our boats run on 12 volts. You're looking for ~16 VDC.

I used Hitachi on the boat, and BP for home. They both were well made and sealed, good for ocean use.

Boris
 
How do you tell if a panel is made in China from this site?

Thanks,
Warren
 
i was not impressed by the 1 year warrenty on the bruntons
 
I guess to find out where the panel are made, you have to ask the distributor. If they say "I don't know," they're from someplace he doesn't want to say. Other than that, use known brands, and you can check their web site. Hitachi are made in Japan, BP are made in the USA, etc.

The BP's had a 25-12-5 year warranty, which was needed to get the Calif rebate. 25-12 was power output, 5 on the panels. Outside of workman
ip, what's there to go wrong with a solar panel?

Boris
 
journey on wrote:
...what's there to go wrong with a solar panel?
Click to expand...
Drop or set something heavy on it, connections can corrode (don't ask on the first one... :oops: )

BTW, as most know, the rigid, thick panels are MUCH more efficient producing energy than the flex panels. But sometimes flex is the best or only way to go. I have a 20 yr old flexible 30 Watt unit, 3/16" thick, I store it under one side of the V-berth, it's about 4ft long by 14-16" wide. I just tie it down on the roof when I need it, works great for my needs, no degradation over the years!
 
I had a Siemens solar panel, the rigid multi crystal type, and they guaranteed it to produce 80 or 90%(can't remember now) of the rated output for 10? years. If the output fell, they would give me a panel to make up the difference.

I think it is important to get a panel with a long warranty.

If the panel costs $300 then the first day of operation it costs $300 per day. After 365 days, the cost has gone down to $0.82 per day. After 10 years the cost is $0.0082 per day or $30 per year.

I used the panel I bought for 15 years and it was still working fine when I sold the boat. I assume the new owner is still using the panel.

A quality solar panel is a good long term investment, with a very low maintenance cost.
 
So, how many watts do people have for their on-board solar panel(s)? 15 watts is just over 1 amp, right? (Watts divided by volts gives amps, if I recall correctly). Some minimum that is useful? I suppose the answer is as many watts as you can afford and fit? But the little 1 watt chargers probably are not terribly useful?


Larry H":2yhkhhzu said:
A quality solar panel is a good long term investment, with a very low maintenance cost.
Click to expand...
 
Pat Anderson":2qindgq4 said:
So, how many watts do people have for their on-board solar panel(s)? 15 watts is just over 1 amp, right? (Watts divided by volts gives amps, if I recall correctly). Some minimum that is useful? I suppose the answer is as many watts as you can afford and fit? But the little 1 watt chargers probably are not terribly useful?

Click to expand...

Pat - yes Watts/Volts=Amps. A 1 watt charger would hence provide only about 1/12 of an amp (83mA) of current. Hence, if your goal is to keep the main batteries charged, it is probably not that useful. Typical tricker chargers (which will maintain the batteries just fine) put out 0.5-1.5A. A panel that does that would maintain your batteries just fine assuming there are not losses other than the normal discharge rate of the batteries.
 
And to add to my 'efficiency' comment of rigid vs flexable panels, that's in terms of the amount of area required to put out the same wattage. Thus a smaller area rigid/thicker panel will put out the same as a larger, flex panel.

P (Watts) = I (amps) x E (Volts), so I = P/E, yep. (I like P=IE for its anchronyms, don't know why...)

On solar panels there are a few factors to consider. When it is advertised for 30 Watts, that is the MAXIMUM it will put out with the sun 'directly' or nearly directly overhead, like at the equator. It is rarely achieved. Also, the current you get out of the panel is dependent on the battery's state of charge. If the battery is already fully charged and you're not using power on the boat, the panel will appear to not put out much current. A panel without voltage regulation (you should regulate above 30 Watts generally), puts out about 16-16.5 volts (open circuit). But the low current output of smaller wattage units generally won't harm your batteries.

I typically get 1.5 amps on a good day with my 30W unit during the 'peak' 4 hours of the mid-day sun in the summer. Winter is less because the sun's is less optimum. That's why you see some sailboats with their solar panels angled to be more perpendicular to the sun, and even some elaborate systems to track the sun!

Oh, and don't forget the diodes on larger panels (or unplug them), when the sun goes down, the panel will actually reverse 'suck' the current out of your system -- slightly.
 
Pat,

For a rigid panel, made with separate cells, the number of cells should be 36 to provide a higher open circuit voltage for charging. This panel is 32 watts. Here is photo of the panel on the Nancy H.

C_Dory_pictures_Feb_2005_011.jpg

To prevent overcharging during storage I disconnected the panel. This panel has internal diodes so night time current drainage was not a problem.
 
Larry H":101fzpf5 said:
If the panel costs $300 then the first day of operation it costs $300 per day. After 365 days, the cost has gone down to $0.82 per day. After 10 years the cost is $0.0082 per day or $30 per year.
Click to expand...

So if you use it 30 times a year is the cost about $10.00 a day?
________
Dave dlt.gif
 
Dave said,

So if you use it 30 times a year is the cost about $10.00 a day?
Click to expand...

Yes, if you throw it away after one year!! :sad

But I said,

I used the panel I bought for 15 years and it was still working fine when I sold the boat. I assume the new owner is still using the panel.
Click to expand...

The panel will also maintain the battery charge during storage outside (not while indoors) without requiring a 120 volt plug in. The panel could also maintain the boat's battery while the boat was stored indoors in a shed with no 120 volt power, if the panel was placed outside or in a shed window(south facing) and wired to the battery.

:wink

Larry H
 
Another cyber mystery--I had asked what was the right sized panel for a C Dory yesterday--sort of answered, but still not sure. I use a couple of watt pannel to maintain the disconnected batteries on my Van I keep in Calif--and it is alway charged up. It seems like 15 watts is more than you need for "trickle charge"--and not enough for substantial power if you are anchored.

If you are cruising and run each day, the 30 to 45 amp alternator (or more for twins) should keep the batteries topped off--perhaps unless you have a refigerator.

So, what is the need for an average C Dory at anchor--using the Wallas, for 2 hours a day, running the small refigerator--figure 2 amps an hour, add in lights, plus satellite radio for a few hours at night? The refigeration would be the largest draw--50 amps? Next would be an anchor light at another 10 amps, finally the sterio for another 10 amps the stove an amp or two. Figure 70 to 80 amps a day? So would two 100 to 150 amp pannels be adequate for "energy independant" for a C Dory? (another arguement against the refigerator--but we have been there)
 
I believe Brent and Dixie have the answer, Dr. Bob. They wrote the following on another thread on refrigerators 2/6/08, but didn't mention how many total watts of panels they have, maybe they'll chime in:
On Discovery we have the Norcold refrigerator and a Weco Fridge/Freezer. They are both hooked to the port battery bank (two D34 Exide Orbital batteries). The batteries are recharged by the port motor, also by solar panels on the cabin roof. I also have a charge line from the truck to the port battery bank. When we travel with the boat, we turn on the fridge and the Waeco when we leave home, and they run 24/7 until we return. Last winter that was from Dec. 25th until the middle of March. Occasionally we have to run our Honda 2000 if there has been a few days of heavy cloud cover, while on the hook. I admit that the fridge, freezer and solar panels have added close to $2,000.00 to the cost of the TomCat, but sure make it nice for cruising. We never have to find the next place to buy ice.

We use the boat as a camper and live in it as we travel across the country-like "Wild Blue", Jim and Joan.
Click to expand...
 
Bob,

I think the way to decide is:

Multiply the amps consumed by each device by the hours of use. That equals amp-hours for each device. Add up the amp hours. That is daily usage. Add 15-20% for recharging inefficiency. This gives amp hours needed per day.

Solar panels might produce for 6 hours per day. So divide the amp hours needed per day by 6 to obtain the charging amps required.

So 100(example) A-H required per day + 15%= 115 A-H divided by 6 hours = 19 amps output. 19 amps x 12 volts = 228 watts.

I would think that two 100 watt panels that run at 18 volts open circuit should provide the needed power in the summer.

However, most C-Dorys run their motors after several days at anchor so actual A-H need may be less.

Consider that if you installed some LED lights for anchor or cabin the A-H needed could be reduced.
 
FWIW, found this ad in today's Harbor Freight paper, probably Taiwanese for sure, no diodes I suspect (they can be added), needs a regulator--who knows it might be in the 'kit', this is a set of three 15W panels, don't know dimensions or thickness, sorry.

SolarPanel_HarborFreight_080210.jpg
 
Our solar panel setup
IM000164.jpg
6 x 15 watt panels, total of 90 watts. They are from Northern Tool, cost $80.00 each on sale. The charge controller is a MMPT type boost controller. The cost was about $100.00 from eBay.
IM000169.jpg
The charge controller is the larger panel in the center of the overhead.
We also use solar panels on our 5th wheel trailer (2 x 120 watts) and on our truck camper ( 1 x 75 watts).
 
As full-time RVers, we have a large solar set-up for our RV. This includes four 75 watt pannels, a charge controller, and four deep-cycle golf cart batteries. But, we probably use a lot more power for 'stuff' than the average C-Dory operator.

We used RV Solar Electric's web site and worksheet to compute our power needs....http://www.rvsolarelectric.com/

It's a good place to start when trying to figure out how to set up a solar system. They offer a free catalog that includes a section on system design and equipment.

Chuck Flanagan
 
I think the most important thing to consider when buying a solar panel is the warranty and will the company stand behind it. Just because it's cheap to purchase doesn't always mean it's the best buy.

Solar panels can fail. I had a Kyocera KC 120 that failed after 7 years and was replaced 100% under Kyocera's warranty, in fact they upgraded mine to a KC 130 panel. When the panel failed I just called the warranty dept. and they sent me the new one with an RA# to return the old one.

I have my panel setup on my " off the grid " cabin in the mountain's with a charge controller, inverter, and 4 deep cycle batteries. I use 12 volts for lights and the inverter for dish TV, computer, ect. I'm sold on solar!!

I don't have solar on my C-Dory but after reading this post I'm going to check it out.

Charlie
 
Back
Top