Is there a source "Choosing marine solar panels for Dummies"? At this time, I think that I want to run, a couple of small fans, and a radio. Milli-amps required? Is there a small refrigerator that could be run on solar? Is switching equipment necessary to get the panels to charge the house battery? I've got an auto/truck supply store close that generally has great prices. Is there a difference in quality or durability between the solar panels intended for campers versus a chandlery supplying marine accessories? I sail on Lake Ontario - not quite polar but definitely lower sun than Florida! Boat is 26 foot. Any preferences on where to mount? Thanks in advance Ralph
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J.B. Dyer
A little More Information
Hi Ralph: I believe that you will need a little more information to get an answer, like, how much battery power do you presently have? Are you normally hooked up to shore power? If so, how long are you away from it on your outings? Also, do you have an alternator that charges the batteries while you are motoring? Everything you have or intend to have runs off of batteries and the solar panel assists the batteries. The trick is to get most of what you are using from the batteries supplemented by the panel. West Marine has advisories in their solar section that might help you to figure out your need. There are several refrigerators on the market that run off of a 12 volt system but none that run completely off of solar power that I know of. I've never had any experience with solars other than marine so I really couldn't say how they would compare with the AutoZone variety. On marine solar systems, instructions normally come that show you how to configure the wiring for multiple banks without switching. As to mounting, the panel needs to be in a place where it can get the most sun without being under foot. There are several swivel type mountings that can be had, or made that allows you to keep it pointed towards the sun. Hope this helps, good luck with it.
Hi Ralph: I believe that you will need a little more information to get an answer, like, how much battery power do you presently have? Are you normally hooked up to shore power? If so, how long are you away from it on your outings? Also, do you have an alternator that charges the batteries while you are motoring? Everything you have or intend to have runs off of batteries and the solar panel assists the batteries. The trick is to get most of what you are using from the batteries supplemented by the panel. West Marine has advisories in their solar section that might help you to figure out your need. There are several refrigerators on the market that run off of a 12 volt system but none that run completely off of solar power that I know of. I've never had any experience with solars other than marine so I really couldn't say how they would compare with the AutoZone variety. On marine solar systems, instructions normally come that show you how to configure the wiring for multiple banks without switching. As to mounting, the panel needs to be in a place where it can get the most sun without being under foot. There are several swivel type mountings that can be had, or made that allows you to keep it pointed towards the sun. Hope this helps, good luck with it.
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Ed Schenck
Learning curve.
Here are a couple of sites that will help answer your questions: www.jackrabbitmarine.com Solatron Technologies(Related Link) But J.B. is right, you need to complete a power requirements spreadsheet and understand your needs. There is one on SailNet. Go there and search on articles for "Calculating Your Electrical Load".
Here are a couple of sites that will help answer your questions: www.jackrabbitmarine.com Solatron Technologies(Related Link) But J.B. is right, you need to complete a power requirements spreadsheet and understand your needs. There is one on SailNet. Go there and search on articles for "Calculating Your Electrical Load".
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Dan McGuire
Perform an Analysis
You need to set down and analyze your needs. I will describe the process I went through. There are two times which demand that I use a lot of power, at night and during a cruise. The cruise is the most demanding. I generally cruise for three days maximum. I will call that a full three days and nights even though it will be three days and two nights. I run the radio (.4A) about 14 hours per day. I will use the depth sounder (.9A) about 8 hours per day. I will run cabin lights (.4A) about four hours. I will use an anchor light (.4A) about 12 hours. This is a total of 24AH per day. I decided to try a 100AH battery and a 10W solar panel. As a rule of thumb a solar panel will deliver an average of 50% of its rated capacity, if it is laying flat. A 10w panel will deliver 10W/12V or .8A. During a 12 hour day, it will deliver .8A times 12 hours times 50% or 4.8AH. Therefore on a cruise, I will use 24AH during the day and recharge 4.8AH during the day or a net loss of about 19.2AH. Therefore over a three-day trip I will lose 19.2AH times three or about 58AH. Since my battery is a 100AH battery, I have plenty of battery. I would expect the battery to fully recharge in 58AH divided by 4.8AH or in about 12 days, if no further power is used. Actually the battery is recharged in about three days. A regulator is only needed to prevent overcharging the battery. You can charge a lead acid battery at less than two percent of its capacity without overcharging. Actually it is better if that rate is kept to one percent or less for a little extra safety. In addition a diode is not required for smaller solar panels. A diode is used to keep the battery from discharging through the solar panel when the panel is not charging. For smaller panels the resistance it high enough that you don’t need the diode. I called Siemens and talked to them about this. They agreed with my analysis. At your higher latitude, you might want to make your panel a little larger (25%??) to account for lower sun angle.
You need to set down and analyze your needs. I will describe the process I went through. There are two times which demand that I use a lot of power, at night and during a cruise. The cruise is the most demanding. I generally cruise for three days maximum. I will call that a full three days and nights even though it will be three days and two nights. I run the radio (.4A) about 14 hours per day. I will use the depth sounder (.9A) about 8 hours per day. I will run cabin lights (.4A) about four hours. I will use an anchor light (.4A) about 12 hours. This is a total of 24AH per day. I decided to try a 100AH battery and a 10W solar panel. As a rule of thumb a solar panel will deliver an average of 50% of its rated capacity, if it is laying flat. A 10w panel will deliver 10W/12V or .8A. During a 12 hour day, it will deliver .8A times 12 hours times 50% or 4.8AH. Therefore on a cruise, I will use 24AH during the day and recharge 4.8AH during the day or a net loss of about 19.2AH. Therefore over a three-day trip I will lose 19.2AH times three or about 58AH. Since my battery is a 100AH battery, I have plenty of battery. I would expect the battery to fully recharge in 58AH divided by 4.8AH or in about 12 days, if no further power is used. Actually the battery is recharged in about three days. A regulator is only needed to prevent overcharging the battery. You can charge a lead acid battery at less than two percent of its capacity without overcharging. Actually it is better if that rate is kept to one percent or less for a little extra safety. In addition a diode is not required for smaller solar panels. A diode is used to keep the battery from discharging through the solar panel when the panel is not charging. For smaller panels the resistance it high enough that you don’t need the diode. I called Siemens and talked to them about this. They agreed with my analysis. At your higher latitude, you might want to make your panel a little larger (25%??) to account for lower sun angle.
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Adam
Try US Solar
I got a flexible and 'walkonable' panel from them. Off hand I don't recal the rating, but am happy with it and their prices. It seems they make the ones alot of people sell. Myelectrical loads aren't all that great, and the panel seems to keep my battery fully charged. AD
I got a flexible and 'walkonable' panel from them. Off hand I don't recal the rating, but am happy with it and their prices. It seems they make the ones alot of people sell. Myelectrical loads aren't all that great, and the panel seems to keep my battery fully charged. AD
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Debra B
don't by solar from marine supply houses
If it says marine - it will cost more. And you can buy the same and more from the true solar suppliers. Ed mentioned Solartron Tech (www.partsonsale.com) - it is a great web site, but their best prices are on a brand you may not know - it is a good brand, but some people want "the brand they know." Northen Arizona Wind and Sun has great prices on large panels and some good information on the variuos charge controllers available today. Good prices on Kyocera, sharp and Shell. They don't carry AstroPower, so you will have to look elsewhere. Do a yahoo search on "solar panel" and you will find a lot of good vendors.
If it says marine - it will cost more. And you can buy the same and more from the true solar suppliers. Ed mentioned Solartron Tech (www.partsonsale.com) - it is a great web site, but their best prices are on a brand you may not know - it is a good brand, but some people want "the brand they know." Northen Arizona Wind and Sun has great prices on large panels and some good information on the variuos charge controllers available today. Good prices on Kyocera, sharp and Shell. They don't carry AstroPower, so you will have to look elsewhere. Do a yahoo search on "solar panel" and you will find a lot of good vendors.
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tom
On My Mac 26
we had two 115 amp hour batteries and this was usually enough for several days at anchor. If you are talking about weekends and don't have enormous power demands you may find that adding another battery is far more cost effective than trying to charge while out. We used the interior lights and anchor light and depth sounder for up to 5 days without a recharge. With a solar panel you are talking 20 amp hours a day maybe a lotless. Doing the math adding a 115 amp hour battery would equal a fairly large solar panel!!!! I just bought a 115 amp hour trolling battery at wal-mart for $60.00. We are planning to live on the hook for longer periods of time and will be buying solar panels. I am thinking about a hard bimini that could hold the panels and collect rainwater. It looks like we are talking over a thousand bucks in solar panels. I would not consider it for weekending!!!! Another alternative might be buying an outboard with a charger. We usually end up motoring some each day. Even though an outboard charger doesn't put out that much power it might be enough for you to make it through the weekend.
we had two 115 amp hour batteries and this was usually enough for several days at anchor. If you are talking about weekends and don't have enormous power demands you may find that adding another battery is far more cost effective than trying to charge while out. We used the interior lights and anchor light and depth sounder for up to 5 days without a recharge. With a solar panel you are talking 20 amp hours a day maybe a lotless. Doing the math adding a 115 amp hour battery would equal a fairly large solar panel!!!! I just bought a 115 amp hour trolling battery at wal-mart for $60.00. We are planning to live on the hook for longer periods of time and will be buying solar panels. I am thinking about a hard bimini that could hold the panels and collect rainwater. It looks like we are talking over a thousand bucks in solar panels. I would not consider it for weekending!!!! Another alternative might be buying an outboard with a charger. We usually end up motoring some each day. Even though an outboard charger doesn't put out that much power it might be enough for you to make it through the weekend.
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Jeff M.
more batteries=less money
I would have to agree with Tom. If you're looking at staying out for only a few days, an extra deep-cycle battery (or two) is going to be a lot more economical than going through the hassle and expense of solar panels. In general, although they are certainly a wonderful thing, solar panels are by far the most expensive way to generate electricity. You also have to consider the mounting arrangement, wiring, keeping them pointed towards the sun, shadowing and a lot of other things to get anywhere near their rated output. If you were going out for a few weeks or more, the equation changes dramatically, but for a few days at a time, extra batteries are definitely the way to go! Keep the wind in your sails, Jeff
I would have to agree with Tom. If you're looking at staying out for only a few days, an extra deep-cycle battery (or two) is going to be a lot more economical than going through the hassle and expense of solar panels. In general, although they are certainly a wonderful thing, solar panels are by far the most expensive way to generate electricity. You also have to consider the mounting arrangement, wiring, keeping them pointed towards the sun, shadowing and a lot of other things to get anywhere near their rated output. If you were going out for a few weeks or more, the equation changes dramatically, but for a few days at a time, extra batteries are definitely the way to go! Keep the wind in your sails, Jeff
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Dan McGuire
Consider Solar Panels
I used a very simple Siemens 10W solar panel plus a 100AH battery for day sails, night sails and short cruises. The panel and all of the wiring, connectors, etc, as I remember, cost less than $150. A simple solar panel, no diodes and charge controller, should last for many years. It is awfully nice to be able to just walk away from the boat and expect to have a fully charged battery when I return. I do agree that more battery capacity may be more useful than larger solar panels, provided the time is available to keep them recharged.
I used a very simple Siemens 10W solar panel plus a 100AH battery for day sails, night sails and short cruises. The panel and all of the wiring, connectors, etc, as I remember, cost less than $150. A simple solar panel, no diodes and charge controller, should last for many years. It is awfully nice to be able to just walk away from the boat and expect to have a fully charged battery when I return. I do agree that more battery capacity may be more useful than larger solar panels, provided the time is available to keep them recharged.
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Bill Coxe
Solar panels
This year, I purchased two 11-watt solar panels, US Solar brand, from two different suppliers, but the average was about $115.00 each. I have two 90 amp-hour, deep discharge batteries which I use for starting the saildrive and house loads. Normally, the panels lie on the stern cockpit seat, one on either side of the tiller mount, and they are wonderful! When cruising, one battery is selected and the other sits and maintains its charge, then after a night of anchor lights and whatever else, I select the other battery and away we go. Between the battery capacity and the panels, and the alternator on the saildrive, life is good, and that includes VHF radio, stereo, lighting internal and external, windspeed and direction instruments, depth sounder and auto pilot. And remember always that I go sailing to get away from it all. (GPS-two each, are battery powered). Extra guests and more cockpit room is needed? Put the panels in the port lazarette, bring them out when the guests leave. Bill Coxe, O28 Kukulcán, New London, CT
This year, I purchased two 11-watt solar panels, US Solar brand, from two different suppliers, but the average was about $115.00 each. I have two 90 amp-hour, deep discharge batteries which I use for starting the saildrive and house loads. Normally, the panels lie on the stern cockpit seat, one on either side of the tiller mount, and they are wonderful! When cruising, one battery is selected and the other sits and maintains its charge, then after a night of anchor lights and whatever else, I select the other battery and away we go. Between the battery capacity and the panels, and the alternator on the saildrive, life is good, and that includes VHF radio, stereo, lighting internal and external, windspeed and direction instruments, depth sounder and auto pilot. And remember always that I go sailing to get away from it all. (GPS-two each, are battery powered). Extra guests and more cockpit room is needed? Put the panels in the port lazarette, bring them out when the guests leave. Bill Coxe, O28 Kukulcán, New London, CT
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tom
solar power doesn't make sense
for a weekender. A 11 watt panel at best puts out 0.62 amps. That's it's best!!!! This might be for only 5 hours a day. I'll give you 6 so that makes 3.6 amp hours a day I'll give you 4!!!! Most anchor lights draw one amp. We'll say that it's on 10 hours a night. Just the amp hours for the anchor light means you discharge 6 amp hours a 24 hour period. After a three day weekend you are 18 amp hours in the hole!!! That means that you aren't out of the hole when you come back in 5 days!!!! I am assuming that you are tied to a dock during the week and have access to shore power. If you are on a mooring then everything changes. I have a 65 amp alternator, running the motor one hour assuming maximum efficency is equal to 100 hours of perfect sunshine with the 11 watt solar panel. At 5 hours a day you are talking 20 days assuming perfect efficency. I kept my mac at the dock for 8 years and with the two 115 amp hour batteries and a charger had no problems. If the batteries were real low I would use a 1 amp trickle charger which is 24 amp hours/day which is 120 amp hours before I got back the next weekend. If I wasn't sure when I'd be back I could use the 10 amp charger to top them off before leaving and then again before heading out the next weekend. It worked well for me. And again you can buy two 115 amp hour batteries for the cost of one 11 watt panel. A 1 amp trickle charger is less than $20.00 and in my experience the trickle charger won't hurt your batteries even if left on all of the time. A smart charger might extend battery life a little but they are expensive. In my experience a deep cycle battery is good for 5-6 years. The water that you use to fill them up is far more important than how you charge them. Tap water kills batteries fast!!!!!!
for a weekender. A 11 watt panel at best puts out 0.62 amps. That's it's best!!!! This might be for only 5 hours a day. I'll give you 6 so that makes 3.6 amp hours a day I'll give you 4!!!! Most anchor lights draw one amp. We'll say that it's on 10 hours a night. Just the amp hours for the anchor light means you discharge 6 amp hours a 24 hour period. After a three day weekend you are 18 amp hours in the hole!!! That means that you aren't out of the hole when you come back in 5 days!!!! I am assuming that you are tied to a dock during the week and have access to shore power. If you are on a mooring then everything changes. I have a 65 amp alternator, running the motor one hour assuming maximum efficency is equal to 100 hours of perfect sunshine with the 11 watt solar panel. At 5 hours a day you are talking 20 days assuming perfect efficency. I kept my mac at the dock for 8 years and with the two 115 amp hour batteries and a charger had no problems. If the batteries were real low I would use a 1 amp trickle charger which is 24 amp hours/day which is 120 amp hours before I got back the next weekend. If I wasn't sure when I'd be back I could use the 10 amp charger to top them off before leaving and then again before heading out the next weekend. It worked well for me. And again you can buy two 115 amp hour batteries for the cost of one 11 watt panel. A 1 amp trickle charger is less than $20.00 and in my experience the trickle charger won't hurt your batteries even if left on all of the time. A smart charger might extend battery life a little but they are expensive. In my experience a deep cycle battery is good for 5-6 years. The water that you use to fill them up is far more important than how you charge them. Tap water kills batteries fast!!!!!!
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Frank Ladd
It all depends on your usage.
I have the same 11 watt Unisolar flexible panel that most folks have. I have a battery big enough for all my loads over a three day weekend. By Sunday the battery is a little low, but by next Friday it is all charged and ready to go. If I was going out for longer I'd triple my battery power and then think about adding a 50 watt or larger panel.
I have the same 11 watt Unisolar flexible panel that most folks have. I have a battery big enough for all my loads over a three day weekend. By Sunday the battery is a little low, but by next Friday it is all charged and ready to go. If I was going out for longer I'd triple my battery power and then think about adding a 50 watt or larger panel.
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Dan McGuire
Tom-Read "Perform an Analysis"
Tom-go back and read "Perform an Analysis". I used very pessimistic numbers for my boat and they still work. Also I measured the current draws and I doubt that an anchor light uses one amp. It is probably closer to a half amp. Don't try to measure the resistance of the bulb and calculate the current draw. It won't work because the resistance changes when they heat up. You can probably save money by using a charger at the dock, but it is hard to beat the convience of a small solar panel.
Tom-go back and read "Perform an Analysis". I used very pessimistic numbers for my boat and they still work. Also I measured the current draws and I doubt that an anchor light uses one amp. It is probably closer to a half amp. Don't try to measure the resistance of the bulb and calculate the current draw. It won't work because the resistance changes when they heat up. You can probably save money by using a charger at the dock, but it is hard to beat the convience of a small solar panel.
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tom
Hey dan experience counts
I don't have a solar panel so can't speak from experience. The 11 watt panel that I looked at only put out .62 amps. Reading Don Casey's book he was not as optimistic as you. I have nothing against solar and think it's great for some applications. I don't understand how a 10 watt panel can produce so much energy but that's very encouraging for me. I had figured that I'd need 4 80 watt panels maybe two 11 watt panels will meet my needs!!!!! Sure save me a lot of bucks!!!!!!!!!!
I don't have a solar panel so can't speak from experience. The 11 watt panel that I looked at only put out .62 amps. Reading Don Casey's book he was not as optimistic as you. I have nothing against solar and think it's great for some applications. I don't understand how a 10 watt panel can produce so much energy but that's very encouraging for me. I had figured that I'd need 4 80 watt panels maybe two 11 watt panels will meet my needs!!!!! Sure save me a lot of bucks!!!!!!!!!!
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Dan McGuire
I don't Understand
First of all, it is possible that for some people solar power does not make sense. But to say as a blanket statement that solar power doesn't make sense, does not make sense. Second. As a worst case analysis your 342Watts of solar panels should deliver 85AH per day (see Wester Marine Advisor on Solar Panels). What are you doing that requires 85AH/day? In addition, my experience says they will deliver more AH than that. Third. Your hypothetical 11Watt panel should deliver 11 Watts/12V or over .9A. Your panel will deliver a higher voltage to a higher voltage device which would give you a lower current, but you are delivering it to a 12V battery. Fourth. You say experience counts and then say that you have no experience. I have been using my solar panel for about two years and I have never had to charge the batteries.
First of all, it is possible that for some people solar power does not make sense. But to say as a blanket statement that solar power doesn't make sense, does not make sense. Second. As a worst case analysis your 342Watts of solar panels should deliver 85AH per day (see Wester Marine Advisor on Solar Panels). What are you doing that requires 85AH/day? In addition, my experience says they will deliver more AH than that. Third. Your hypothetical 11Watt panel should deliver 11 Watts/12V or over .9A. Your panel will deliver a higher voltage to a higher voltage device which would give you a lower current, but you are delivering it to a 12V battery. Fourth. You say experience counts and then say that you have no experience. I have been using my solar panel for about two years and I have never had to charge the batteries.
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tom
Hi Dan
I do believe experience counts and I am listening to your advice. My boat has a refrigerator that I'd like to use while at anchor. Also the auto-pilot draws some amps. As Don Casey advised I added up projected amp hours and projected energy from solar panels and came up with four 80 watt panels. I might buy one panel and see how it performs before making a commitment. But once I'm at anchor in the Bahamas I want cold beer!!!! Ice is too hard to come by while at anchor. We also like ceviche which must be kept cold. My limited experience with chartering showed that in general running the motor for an hour or two a day kept the batteries charged but they didn't have refrigeration. Some have recommended bigger or multiple alternators but batteries won't accept too much charge all at once. With the new boat a Pearson 323 I don't have enough experience yet to know how to keep the batteries charged. It has a built in charger so the batteries are full when we leave the dock but we've only done a couple of overnighters so far. As to my previous boat the Macgregor the anchor light drew the most power especially in the winter with the longer nights. we kept the depth sounder on while sailing but that was usually only 4-5 hours /day. It was strictly for weekends and once or twice a year maybe a week at a time. I am definately going to get more information before I spend big bucks on solar!!!! Hopefully from someone like you who has experience and isn't trying to sell something... The soloar sellers keep saying that you need more panels to provide X amount of amp hours. I figured that they were bragging about how much juice their panels provided and that reality would be less. It seems that they are doing the oppisite to get us to buy more than we need..
I do believe experience counts and I am listening to your advice. My boat has a refrigerator that I'd like to use while at anchor. Also the auto-pilot draws some amps. As Don Casey advised I added up projected amp hours and projected energy from solar panels and came up with four 80 watt panels. I might buy one panel and see how it performs before making a commitment. But once I'm at anchor in the Bahamas I want cold beer!!!! Ice is too hard to come by while at anchor. We also like ceviche which must be kept cold. My limited experience with chartering showed that in general running the motor for an hour or two a day kept the batteries charged but they didn't have refrigeration. Some have recommended bigger or multiple alternators but batteries won't accept too much charge all at once. With the new boat a Pearson 323 I don't have enough experience yet to know how to keep the batteries charged. It has a built in charger so the batteries are full when we leave the dock but we've only done a couple of overnighters so far. As to my previous boat the Macgregor the anchor light drew the most power especially in the winter with the longer nights. we kept the depth sounder on while sailing but that was usually only 4-5 hours /day. It was strictly for weekends and once or twice a year maybe a week at a time. I am definately going to get more information before I spend big bucks on solar!!!! Hopefully from someone like you who has experience and isn't trying to sell something... The soloar sellers keep saying that you need more panels to provide X amount of amp hours. I figured that they were bragging about how much juice their panels provided and that reality would be less. It seems that they are doing the oppisite to get us to buy more than we need..
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