solar panels

Fairwind · Dec 2, 2008

15 watts, that's about 1 (one) amp will maintain a 200 amp-hour battery bank. (two group 27 deep cycle batteries). But it will not provide working power for lights, stereos, GPS units and lap-tops. Something else will have to provide that power..Don't expect a 15 watt panel to "charge your batteries back up" once they are discharged..For that you will need a 50 or 75 watt panel, which will provide 3 or 5 amps of charging current..

newly anonymous · Dec 2, 2008

amorphous in AZ?

It seems to me that the heat factor down there would lead one to use a multicrystalline PV. Am I missing something, other than the lower cost of an amorphous panel?

Ctskip · Dec 4, 2008

Re: amorphous in AZ?

You guys are starting to get to where the layman can understand what it is you are talking about. Please

Keep it up,
Ctskip

sailingdog · Dec 4, 2008

Amorphous panels are generally easier to install, being semi-rigid and durable enough that they can be walked on.

newly anonymous said:
It seems to me that the heat factor down there would lead one to use a multicrystalline PV. Am I missing something, other than the lower cost of an amorphous panel?

flhunterowner · Dec 4, 2008

solar

Just like Lee I installed 2 15 watt solar panels and a charger from northern tool. I bought (1) extended warranty ( it was like 10.00) and it covers the cells even if i drop a wrench on it. You can use the warranty for either of the panels.

My panels voltage is about 19 volts during midday. It drops of course at dusk and dawn and when in shadows (liek the sails)

I mounted them both above my bimini using aluminum angle pop riveted to make a frame.

They keep both of my batteries charged and even run a few fans directly during the day. (I installed a switch so the charger either charged the batteries or supplied power directly to my fuse/switch panel.

For the money i spent (less than 300.00) it has worked out really well for me. I used to show up to the boat every other week to find my batteries about drained.

Ctskip · Dec 4, 2008

Re: solar

I've had my 1983 31 ft Allmand for about five years now and I just replaced one 12 volt with two sixes. Learning about the AHr's They went dead in a short time, three months about. I replaced the charger. No help. That's a $150 over the side. I checked the old charger out on my bench and it works fine. So I guess I'll put her back in. Finding someone who knows what they are doing is a nightmare. Who does one trust. I don't mind paying good money, but I want good in return There's only one guy around here that even works on boats and it can't be done at the marina, he has to take it to his shop some distance away. I've already had a problem with some work he did. He's one of those, Jack of all trades. So wanting another professional job is out of the question. I beginning to wonder if I made the right choice as far as placement of my boat. Maybe along the shore would of been better choice as far as finding qualified people to actually do some quality, professional work . Not only do it right the first time, but do it neatly also. I guess good help is hard to find.

So I was thinking about disconnecting the charging system entirely and placing a small solar setup on her. With what I have been reading about being plugged in at the dock and my neighbors boat affecting mine. I went down and disconnected my cord. Now I only plug in when i need a quick charge. With all this discharge and charge rate has me swimming around in circles. Of coarse I want my batteries to last forever, who doesn't?

Anyway, I appreciate the candid conversation about solar and I know it's coming of age now and becoming affordable, so I'll look at little closer at it. Thanks for all the frank talk. I appreciate it.

Keep it up,
Ctskip

sailingdog · Dec 5, 2008

CTSkip-

It'd help if you said more about exactly how the charging and batteries are setup on your boat. If you had two reliable golf cart batteries, something must be fairly drastically wrong for them to die in just three months. Batteries have a much longer life than that, and a problem in the way you're charging them, maintaining them or using them is generally the reason for such a short life.

However, you should probably start a new thread on it, so as not to hijack this one.

Ctskip said:
I've had my 1983 31 ft Allmand for about five years now and I just replaced one 12 volt with two sixes. Learning about the AHr's They went dead in a short time, three months about. I replaced the charger. No help. That's a $150 over the side. I checked the old charger out on my bench and it works fine. So I guess I'll put her back in. Finding someone who knows what they are doing is a nightmare. Who does one trust. I don't mind paying good money, but I want good in return There's only one guy around here that even works on boats and it can't be done at the marina, he has to take it to his shop some distance away. I've already had a problem with some work he did. He's one of those, Jack of all trades. So wanting another professional job is out of the question. I beginning to wonder if I made the right choice as far as placement of my boat. Maybe along the shore would of been better choice as far as finding qualified people to actually do some quality, professional work . Not only do it right the first time, but do it neatly also. I guess good help is hard to find.

So I was thinking about disconnecting the charging system entirely and placing a small solar setup on her. With what I have been reading about being plugged in at the dock and my neighbors boat affecting mine. I went down and disconnected my cord. Now I only plug in when i need a quick charge. With all this discharge and charge rate has me swimming around in circles. Of coarse I want my batteries to last forever, who doesn't?

Anyway, I appreciate the candid conversation about solar and I know it's coming of age now and becoming affordable, so I'll look at little closer at it. Thanks for all the frank talk. I appreciate it.

Keep it up,
Ctskip

Ctskip · Dec 5, 2008

sailingdog,
I'm not looking to hijack anything. I'm complimenting the thread. I just thought Id' give a little background showing some of my frustration, as to why I appreciate this thread so much.
Where, in your mind, sailingdog, did I attempt to hijack the thread? By giving some background as to why I appreciate this thread so much? Thanks for your advice. I'll keep it in mind.
You really don't have to quote the entire post. I know what I said.

Now where was the hijacking? You are the one that took it off coarse.

Keep it up,
Ctskip

sailingdog · Dec 5, 2008

CTskip-

I was saying that if you wanted to discuss your DC charging problem further... that you should start a new thread as to not hijack this one.

Ctskip said:
sailingdog,
I'm not looking to hijack anything. I'm complimenting the thread. I just thought Id' give a little background showing some of my frustration, as to why I appreciate this thread so much.
Where, in your mind, sailingdog, did I attempt to hijack the thread? By giving some background as to why I appreciate this thread so much? Thanks for your advice. I'll keep it in mind.
You really don't have to quote the entire post. I know what I said.

Now where was the hijacking? You are the one that took it off coarse.

Keep it up,
Ctskip

flhunterowner · Dec 5, 2008

solar

CTSKIP

Start a new thread or PM me if you like and I would be happy to give you some ideas on your charging problem.

Sailingdog may have not meant to quote your entire message, I think it does it automatically when you click reply.

Fairwind · Dec 6, 2008

Just don't expect 5 watts (300ma) to charge a low battery..It will maintain a fully charged battery..

Ctskip · Dec 7, 2008

My question would be. With 5 watts being enough to keep the battery topped off. What happens to the 5 watts once the battery is fully charged? Where does the 5 watts go? When does the panel stop charging? Batteries can be overcharged, yes? Thereby shortening the life of the battery.

Keep it up,
Ctskip

sailingdog · Dec 7, 2008

It depends on the battery bank size and what chemistry they're made up of. In the summertime, wet cell batteries can self-discharge almost 1% per day, where AGM and Gel batteries would self-discharge at a much lower rate. If your batteries are wet-cell, I seriously doubt that the 5 Watt panel can keep up with the self-discharge rate, since it only supplies 1.7 amp-hours a day at best.

As for where the 5 watts of energy would go once the batteries are topped off...it would be spent as waste heat in attempting to charge the already charged batteries. If the panel is small enough, this isn't much of a problem. If the panel were larger, you'd really need a charge controller to prevent it from boiling off the electrolyte in the batteries or overcharging them.

Ctskip said:
My question would be. With 5 watts being enough to keep the battery topped off. What happens to the 5 watts once the battery is fully charged? Where does the 5 watts go? When does the panel stop charging? Batteries can be overcharged, yes? Thereby shortening the life of the battery.

Keep it up,
Ctskip

sailingdog · Dec 7, 2008

If you have a two-Group 27 wet-cell battery house bank (about 210 amp-hours in size), the self discharge rate is going to be about 2 amp-hours per day. If you don't have perfectly sunny days all the time, the batteries will be slowly discharging over time, since the 5 watt panel can only put back a maximum of about 1.7 amp-hours per day. :naughty:

If your house bank is smaller, or AGM/Gel chemistry, yes, the 5 watt panel will probably be enough to maintain the batteries most of the time. However, if you use them and don't recharge them using something else, it is very unlikely that a 5 watt panel will do you much good at all.

sand sailor said:
this isnt for charging a dead battery just keeping it maintained for the period of rest between use i think its plenty

Ross · Dec 7, 2008

Dog, Since Sandsailor is in Arizona I rather doubt that cloudy day are a large problem. Also a 5 watt panel is only a five watt panel when the current flow times the voltage equals five watts. When the battery voltage equals the output voltage of the panel there will be no current therefore no power.

sailingdog · Dec 7, 2008

Ross-

Most panels put out considerably more voltage than the 12.6-12.7 VDC that a fully charged battery will have. Most solar panels are closer to 18 VDC.. so I seriously doubt the batteries will ever EQUAL the panel's voltage, especially given the strength of an Arizona sun.

Ross · Dec 7, 2008

Dog, We're gonna keep each other honest.