Solar Charging System

[csmithers]

Requirements: I'm going cruising full time to California & Mexico on a 33ft sailboat, leaving in a month and planning never to set foot on a dock unless I absolutely have to. I need to get my act in gear regarding solar panels and charging asap. I have LED running lights, VFH, AIS, LED cabin lights, a laptop used as a chart plotter and I expect my power usage to be around 36 AH per day normally. This is basically peanuts. No 'fridge, no big entertainment system, so pretty small setup here.

Current setup: I have two identical battery banks with 2 6V AGM golf car batts in series (i.e. 12v setup) each for a total of around 400AH. They are connected by a battery selector switch that allows me to combine them if necessary. All the charging right now from the alternator and shore power based battery charger is to the battery selector switch. The starting solenoid/motor is hooked up to the battery selector switch as well. I realize this is not ideal, but it was set up by the previous owner. The batteries are 6 years old and I will probably be replacing them with 2 Group 4D AGM batteries at around 200AH each for a total of 400AH since I don't trust these batteries.


Solar plan: I'm planning on getting 2 Kyocera KD140SX-UFBS 140W panels and hooking them up in parallel to an MPPT charge controller on the battery selector switch, and when charging only having an individual battery selector to prevent overcharging and optimal charging. This is overkill and may be incorrect as I know. Due to how my boat is set up there is no good place to mount solar panels without a lot of shading so in essence most of the time one panel will be shaded, but it's not physically impossible that both panels will be putting max output at the same time. I plan to get a Blue Sky Solar Boost 3024DIL (30amp) that will handle the max load and in case I want to get a few more panels. My other option is to get two smaller controllers and charge both batteries independently, but as I understand you typically do this when you don't have a battery selector switch that can combine the two banks one battery charges off of the other (which as I undertand is a bigger no no). Another option is to use the feature of this charge controller that allows for two batteries, but yet again I run into the problem of later if they're combined they'll be charging off of each other.

AC plan: I don't have a lot of devices that need AC. I need it though for some power tools, and some once in a while appliances. I'm thinking instead of mounting an inverter I could just get a Honda 2000 generator with an inverter on it. It can also act as a secondary charging source just in case, will be less setup, and really not that much more expensive than a real inverter ($1000 vs $500). I also have a Honda 2hp outboard so it won't be too crazy to carry fuel for both since both are 4-strokes.

So any advice on my plan before I shell out the big bucks. I need to make a decision very soon to account for shipping and installation before I go!

[btrayfors]

One way to save $$$ is to use flooded batteries (e.g., Trojan T-105 golf-carts) in lieu of AGMs. There are lots of reasons NOT to use AGMs, including the fact that they must be FULLY charged frequently or they lose capacity rapidly.

Another reason has to do with your charging capability. Very few cruising boats have enough charging capacity to take advantage of AGMs. Four AGM golfcart batteries can take upwards of 450-500 amps when they are just 50% discharged. While this dials back fairly quickly, you still need lots of charging capacity to make the AGM savings worthwhile.

Your plan for solar panels sounds OK. If installed correctly, and with a good regulator, they can help keep the batteries charged.

Your 36AH per day estimate seems quite low. The laptop alone will consume upwards of 100AH when run 24 hours per day while sailing. Even running just a few hours per day will consume quite a bit.

And, later on you may wish to add some sort of refrigeration. A total capacity of 440AH (220AH usable @ 50% DOD) would be enough to support such an option.

You didn't mention the size of your existing alternator, or how it's regulated. This is important both for charging options and for suggesting how best to use your current setup of two banks. Normally, it's best to run as one large bank because you draw down only about half as much current and thereby significantly increase the available total AH capacity. Also, it makes things easier, not having to switch anything.

Bill

[csmithers]

Yes, you're probably right about that. All my wired running gear including VHF and AIS take about 1 amp. So that's basically 24AH + laptop which I assume I'll be charging about 4 hours @ 4amps which is about 48 AH so yes I miscalculated there it will be about 72AH in total. Thanks for catching that.

Regarding batteries, flooded are definitely cheaper so that's attractive. I didn't realize the difference between AGM and flooded regarding this though. Thanks for pointing that out. What about gel cell, does it suffer from the same problem?

Thanks!

[Frigoboat Info]

Due to the fact that some shading is almost inevitable on boats, you should use one controller per panel and parrallel the outputs to the battery(s). Most MPPT controllers on the market are designed for land-based installations where shading is not issue, but Genasun has a line of high-efficiency MPPT controllers specifically designed for marine use. They show the combination of a Kyocera 140w panel and their GV-10 controller here: Kyocera + Genasun | Genasun

[btrayfors]

Originally Posted by csmithers

Yes, you're probably right about that. All my wired running gear including VHF and AIS take about 1 amp. So that's basically 24AH + laptop which I assume I'll be charging about 4 hours @ 4amps which is about 48 AH so yes I miscalculated there it will be about 72AH in total. Thanks for catching that.

Regarding batteries, flooded are definitely cheaper so that's attractive. I didn't realize the difference between AGM and flooded regarding this though. Thanks for pointing that out. What about gel cell, does it suffer from the same problem?

Thanks!

Gels are an excellent choice for many cruisers, though they have sort of faded into the background because of all the AGM hype. Now that folks are realizing that the AGM choice isn't always a good one, there seems to be renewed interest in Gels.

Only caution with gels is that they need to be charged at their recommended voltages. And, of course, they are about twice as expensive as flooded batteries, even a bit more than AGMs.

Bill

[csmithers]

Originally Posted by Frigoboat Info

Due to the fact that some shading is almost inevitable on boats, you should use one controller per panel and parrallel the outputs to the battery(s). [/url]

Interesting. Thanks for the lead. I'm fine with doing something like this - however, as I understand putting multiple chargers that aren't wired to each other will mean that only one is working at any one point, which is probably fine. However, as I understand if both of these are outputting the same voltage but at different amperage who knows if the shaded panel will be the one that wins? I'd just like to understand logically how this works before I make a decision.

Thanks.

[csmithers]

Originally Posted by btrayfors

Normally, it's best to run as one large bank because you draw down only about half as much current and thereby significantly increase the available total AH capacity. Also, it makes things easier, not having to switch anything.

Bill

This is a fantastic and non-trivial distinction that seriously hadn't occurred to me before. Much appreciated. Damn voltage drop!

[Adelie]

I would think again about getting AGM's. You are trading off lack of maintenance required and resistance to physical abuse (AGM's) for longevity and ability to maintain the cells (FLA). See this link for a good rundown: Systems. (#29)

If your cruise is only going to be a couple, three years then the AGM's are fine. If it is more open ended, I would go with the FLA's. As long as you can force yourself to check cells monthly, top up water and occasionally equalize you should get significantly longer life out of the FLA's. If not, then expect to get the same or a little less life from the FLA's and the question becomes one of cost and ability to replace.

Gel's are very touchy about charging voltages. Abuse them once any you may have lost capacity or they may be shot.

For house batteries on a sailboat, there should not be significant physical abuse from vibration if the batteries are appropriately secured so there is no advantage for AGM's in that regard.

If you were talking a battery in a dinghy, AGM for sure but that's a different situation.

I would put both batteries in a single bank, remembering to feed the positive and negative from opposite ends so all the cells get equal treatment. I would consider putting a small starting battery in a separate bank with a separate small 1-5w solar panel to keep it topped up. You will get more power out of the batteries together than you will individually and you will be less likely to overdraw one side and decrease it's change capacity.

For mounting the panel consider: Atom Voyages - The Solar-Tracker (Sold Out Nov 2012)
I'm not sure you could mount anything that big this way, but maybe 2 65-80w mounted this way plus a 140w mounted over bimini or cabintop.

I got a 1000w (2000w surge) inverter from WM for about $100, $200 with cabling and connectors. The highend inverters with chargers built in are pointless if you are not going to be at the dock much. For another $50 I plan to get a small solenoid and a light timer so I can turn inverter on with the timer and I don't forget and leave it running.

[scoobert]

Originally Posted by csmithers

Solar plan: I'm planning on getting 2 Kyocera KD140SX-UFBS 140W panels and hooking them up in parallel to an MPPT charge controller on the battery selector switch, and when charging only having an individual battery selector to prevent overcharging and optimal charging. This is overkill and may be incorrect as I know. Due to how my boat is set up there is no good place to mount solar panels without a lot of shading so in essence most of the time one panel will be shaded, but it's not physically impossible that both panels will be putting max output at the same time. I plan to get a Blue Sky Solar Boost 3024DIL (30amp) that will handle the max load and in case I want to get a few more panels. My other option is to get two smaller controllers and charge both batteries independently, but as I understand you typically do this when you don't have a battery selector switch that can combine the two banks one battery charges off of the other (which as I undertand is a bigger no no). Another option is to use the feature of this charge controller that allows for two batteries, but yet again I run into the problem of later if they're combined they'll be charging off of each other.

AC plan: I don't have a lot of devices that need AC. I need it though for some power tools, and some once in a while appliances. I'm thinking instead of mounting an inverter I could just get a Honda 2000 generator with an inverter on it. It can also act as a secondary charging source just in case, will be less setup, and really not that much more expensive than a real inverter ($1000 vs $500). I also have a Honda 2hp outboard so it won't be too crazy to carry fuel for both since both are 4-strokes.

So any advice on my plan before I shell out the big bucks. I need to make a decision very soon to account for shipping and installation before I go!

skip the mppt
here is a solar panel 2 pack that cost $268 for 316 watts
http://www.dmsolar.com/dm15somo2pkp.html

here is a charge controller for the set
C60
it could do 4 panels :P
it will not overcharge, thats why it is a charge controller

total package price
under $425
why doesn't everyone have solar?

[csmithers]

My trip is only going to be a year. Based on the cost and the fact that I don't mind the maintenance on the flooded batteries I think I'll probably choose those. I like your idea about separating the main house and the starting battery.

I can probably take your advice and get a cheaper starting battery and hook up the alternator + regulator and starting coil to that to make it independent of the house batteries. Top that off with a trickle charger like you're saying and I'll be gold. Then I can take out the battery selector switch and replace and replace it with an on/off switch as you suggest. That's more of a longer term project though since I'm in a bit of a crunch right now.

Thanks everyone for the advice! I think I have enough to starting buying things now and hope to god they get shipped to me before my departure date :-)

[csmithers]

Originally Posted by scoobert

skip the mppt
here is a solar panel 2 pack that cost $268 for 316 watts
DM 158w solar panel, solar module 158w, 12V Solar Panel

here is a charge controller for the set
C60
it could do 4 panels :P
it will not overcharge, thats why it is a charge controller

total package price
under $425
why doesn't everyone have solar?

Holy ****, the price per watts is on that is insanely cheap. They even have 18% efficience which is massive which makes the cost even lower. They're a perfect fit too. Thanks for the lead!

[scoobert]

Originally Posted by csmithers

Holy ****, the price per watts is on that is insanely cheap. They even have 18% efficience which is massive which makes the cost even lower. They're a perfect fit too. Thanks for the lead!

your welcome. i became well versed in solar when i was in the planning stage of building a solar powered cat.

[foggysail]

Originally Posted by Adelie

If your cruise is only going to be a couple, three years then the AGM's are fine. If it is more open ended, I would go with the FLA's. As long as you can force yourself to check cells monthly, top up water and occasionally equalize you should get significantly longer life out of the FLA's. If not, then expect to get the same or a little less life from the FLA's and the question becomes one of cost and ability to replace.

Not so IF YOU HAVE A DECENT REGULATOR. It is overcharging that boils out the water. I used to have a water problem with an old ferroresonant charger. No more with modern 3 stage charging along with my solar regulator. This spring I added just two quarts of water (total) since last spring into my 4 golf carts, two group 29s used for my 24vdc system and one group 28 for my genny. That is a total of 30 cells or about 2 ounces/cell after a year!

Originally Posted by scoobert

skip the mppt
here is a solar panel 2 pack that cost $268 for 316 watts
DM 158w solar panel, solar module 158w, 12V Solar Panel

here is a charge controller for the set
C60
it could do 4 panels :P
it will not overcharge, thats why it is a charge controller

total package price
under $425
why doesn't everyone have solar?

I purchased 4 of the dmsolar panels last year, installed 2 then and the other two a few weeks ago. They are a GREAT BUY! I agree with your recommendation.

[Badsanta]

Just a thought on using 2 battery banks. Use one or the other. If one goes dead dont combine them. The dead side will pull the life out of the full one and you end up with 2 low banks. I use one house bank with a starter battery charged by an echo charger from the house bank. Works for me.

[willardj]

Originally Posted by scoobert

skip the mppt
here is a solar panel 2 pack that cost $268 for 316 watts
DM 158w solar panel, solar module 158w, 12V Solar Panel

here is a charge controller for the set
C60
it could do 4 panels :P
it will not overcharge, thats why it is a charge controller

total package price
under $425
why doesn't everyone have solar?

I have these panels on my sailboat and have to say they are nice for the $$. I am building a new shed out back that I am planning on putting 6 of these on to run the whole shed. The one thing you have to remember is shipping it runs $100 to $120 for these panels and $20 or so for controller.