Solar tracking mount

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vanguard64
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Solar tracking mount

Post by vanguard64 »

I have an Alberg 30 with two group 27 flooded batteries of 80ah each. One handles engine start and the other is for house use. I have a battery isolator between them and a smart electric charger on shore power. My alternator is a 55 amp unit. The boat is kept in a slip and daysailed 80 % of the time. The other 20% is dedicated to 2-5 day cruising. My amp use for cruising is approx. 20-25 amps per day. I have looked at purchasing a 55-75 watt solar panel and have looked at James Baldwin,s solar tracker which he no longer makes but offers the schematics for one. Has anyone built one on their own? The one that is similar to James’ and sold by Custom Marine Products is quite an expense.
Thanks
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atomvoyager
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Re: Solar tracking mount

Post by atomvoyager »

Unless you plan to run your motor nearly every day it seems like adding to your battery bank is a priority. One GP 31 (105 AH) for house bank is a minimum and two is much better. You can only use 50% of battery capacity without damage to the battery so your current battery only gives you 40AH and less as it ages. One or two tracker mounts is best but with your limited cruising plans you don't need the best - just adequate. You could place one 50-80 watt panel flat on the center of your pushpit rail and make your own simple mount using two aluminum flat bars with two rail clamps to go over the rail and one or two tubes from aft end of panel to the taffrail to stabilize it.

https://www.defender.com/product3.jsp?p ... id=2014957
vanguard64
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Re: Solar tracking mount

Post by vanguard64 »

James,
Thanks for the practical answer. I failed to realize that I can't really go past 50% discharge when calculating battery capacity without damaging the battery. I saw a similar setup to the solar panel you describe on marinehowto.com or phase.com.
Marcelo
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Re: Solar tracking mount

Post by CapnK »

Marcelo take a look at golf cart batteries. They are 6V but if you'll run two in series you get a nice 12V 105Ah bank that can handle deep discharge with aplomb. Plus about an extra 100#'s of ballast. ;)

The local cart store guy steered me away from the traditionally recommended Trojan batteries, telling me that their quality has declined. Instead, he recommended US Battery, and I have been happy with them. Two years ago I paid about $85 per battery.

http://usbattery.com/
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markwesti
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Solar

Post by markwesti »

Thanks for the tip on the US batts. CaptnK , we have 2 6V T105 Trojans and 1 12v starting batt. that I pretty much don't ever use . It's really just there to complete the circuit . One 6 v batt. is pretty heavy and takes up almost as much room as one 12v , anyhow here is the solar and regulator set I have .
https://www.ebay.com/itm/HQST-100-Watt- ... rk:13:pf:0
This panel is so light and thin .
This is my regulator.
https://genasun.com/all-products/solar- ... ontroller/

To mount the panel I made a frame out of oak , it clips onto my life lines and has a stantion that goes down to my head sail track on the toe rail and clips in . For tracking we just move it to the other side .
I should say that our Amp Hours consumption are small we don't even have a reefer .
vanguard64
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Re: Solar tracking mount

Post by vanguard64 »

I have been waiting for my present batteries to start getting weak (based on specific gravity readings) to tackle purchasing new batteries and adding a solar panel (50w on stern pulpit)and the time is getting close. I have been reading about the subject to make the best possible decision. I presently have 2 identical dual purpose West Marine batteries with 80 ah each. I would like to replace these with 2 identical gp 31 wet cell batteries with 105 ah each. The Atomic4 doesn't take much capacity to start. Being that batteries last longer when their depth of discharge is shallow and to simplify matters, my thoughts are to parallel the batteries at all times. In other words, both batteries would be used to start the engine and be used for house loads. My loads are light, between 20-25 ah per 24 hours and my cruising is limited to 2-3 days max for now. I realize that without having a designated starter battery, I run the risk of depleting the batteries to where I can't start the engine but isn't there a way of monitoring their depth of discharge? Besides an alternator, I also have a smart charger on shore power but I don't like reliance on these.
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Re: Solar tracking mount

Post by atomvoyager »

You can monitor the battery state of charge with a Victron battery monitor or a somewhat less accurate way by looking at the voltage on the display of your solar charge controller. If you are are trying to keep the wiring simple then yes you should be able to avoid flat batteries running a single bank. But it shouldn't be that complicated to wire them in two banks and keep the engine start battery in reserve.
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Re: Solar tracking mount

Post by vanguard64 »

I have 3 more questions regarding installation.
1. Should the solar panel be disconnected when the engine is running or the inboard electric battery charger is being used? Wouldn't the alternator or electric charger output be affected by the voltage from the solar panel?
If so, would you need a switch somewhere between the panel and the controller?
2. What type of wire is best to use between the panel and the controller?
3. If I have 2 deep cycle batteries to charge from one controller, should I buy a dual output controller and connect each lead to the individual batteries or buy a single output controller and connect it to the common on the battery switch?
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Re: Solar tracking mount

Post by atomvoyager »

Yes, the solar panels stay connected all the time regardless of engine alternator, wind genertor or anything else. The solar charge controller will automatically shut off the solar input when the battery voltage is high due to other charging source. You can see how I connect my solar panels at 25:00 in the following boat wiring video:

https://www.youtube.com/watch?v=PofFOg9H_6Y

I have switches to shut off each solar panel mostly for monitoring purposes. A switch is optional but I think it's useful. You size wiring according to the amperage carried. In practice, for minimal voltage loss a 50 watt panel uses 12 AWG tinned duplex and a 100 watt can use 10 AWG. Wiring connection to the batteries does not depend on how many batteries you have but on how many battery banks you set up. For a single bank just run the wires to any of the batteries. For two banks the common way is to have a dual bank controller. Or you can run the solar output to the house bank and manually turn the switch to all when you have plenty of extra solar input and want to top up the engine bank. I don't connect the solar output to the common output on the battery selector switch because when the battery switch is off the solar can back feed the switch panel, which is not good. There are other ways to wire as well and maybe someone will post their method.
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Re: Solar tracking mount

Post by vanguard64 »

I think what makes it confusing to me is that on my boat, the battery switch has the classic Off, 1, 2, and Both positions. So it is my understanding that the 2 batteries are only in parallel when the switch is in the Both position. As they are, the batteries share a negative but they only share a positive through the switch. This is why when I want the alternator charging both batteries at the same time, I keep the switch on Both. The system is set up so one battery is the "start" and the other is the "house". My plan, in order to keep things simple once I purchase the two new deep cycle batteries is to use the switch on Both at all times and in essence using them as 1 bank. The issue is how to charge them with the solar panel. One thought I had was to purchase a controller that can manage 2 batteries at once distributing half of the charge to each one.
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Re: Solar tracking mount

Post by svMira »

I installed one of the Blue Sea Add-a-Battery (https://www.bluesea.com/products/7650/A ... Kit_-_120A) switches when I rewired my batteries. I use two lead 27s for house and something smaller for my starter. This way I know, no matter what, when I come to my boat on the weekend, everything has been charged up with the solar. As far as I can tell, it is working as planned.
I upgraded my solar charge controller to a Genasun GV-5(https://sunforgellc.com/gv-5/), it has a neat feature of a line-out direct from the solar, that won't empty your batteries. There's some kind of load limiter built in that cuts out once the battery charge depletes to a certain level. So you can wire your constant-on items to that, knowing that they won't run your batteries flat if for some reason the draw gets too high or there isn't enough sun to recharge. So far I'm happy with this combination.
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Re: Solar tracking mount

Post by atomvoyager »

The Add-A-Battery switch looks like a good solution. Otherwise, if you're looking for the simplest, cheapest solution just leave the battery selector switch wired for two banks and take the positive wire from the solar controller output to the house battery positive terminal and regulate the charging yourself as I described earlier. You can always change or add to it later.
vanguard64
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Re: Solar tracking mount

Post by vanguard64 »

Thank you for all the good advice. I have been shopping around for a 50-80W solar panel to mount off the stern pulpit. From my understanding of solar panels, for those of us that live in the south, it is best to use a 36 cell panel in order to offset the decrease in voltage that occurs as the panel heats up under the sun. From the ones I looked at on the internet, the number of cells in the panel is not reported in the specs. I actually called Renogy and found out that their 50 or 80w panels only have 33 cells. Are there any recommendations from the group?
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Re: Solar tracking mount

Post by atomvoyager »

I'm not expert in solar panel construction but as I understand it they say 36 is better because of higher voltage. Each cell has a theoretical output of .5v so 36 cells is 18v and 33 is 16.5. Because of inefficiency at high temps and other issues each cell might drop to .45 volt or so, bringing them down to say 16.2 and 14.85. The 36 cell panel may charge better in certain conditions or when the battery bank is nearly full. The 33 would be less likely to fry your batteries quickly if the controller failed, which is not uncommon. In recent years manufacturers claim their cells or wiring methods have reduced losses which makes it unnecessary to have 36 cells because they achieve similar voltages at 33. I don't know about that but maybe that is what Kyocera did. The sales person who answers the phone wouldn't know but you can download the specs on each panel from different manufacturers and look at the voltage ratings. That may not tell the whole story if they all use different testing parameters. Also, an MPPT controller may make a difference. Although I haven't done an accurate test, I haven't noticed a difference in charging between the 36 I used in the past and the 33 I now have on my boat so I think it must be a minor effect in my situation. I got the 33 cell because is more commonly available cheaply and works well enough. Maybe someone more knowledgeable on this can tell us more.
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Re: Solar tracking mount

Post by vanguard64 »

In reference to the wiring from the panel to the controller, I see that if I use duplex wire or any other wire, I will need to crimp a female and male MC4 connector to the ends in order to plug them into the MC4s that come with the panel. If I am not mistaken, I will need to purchase an MC4 crimper and plastic tool to both crimp the wire to the connectors and then screw the parts of the connectors together. I also see that Renogy for example sells 10g or 12g wire of different lengths that have the MC4 connectors already attached to one end. This would save me having to purchase the crimper which I probably won't use again for a long time. Is there a disadvantage of buying these wires over the duplex type in terms of durability or conductivity?
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Re: Solar tracking mount

Post by atomvoyager »

I usually cut off the MC4 connectors and use my own standard crimp spade connectors wrapped with rigging tape for waterproofing. The MC4 cost more or need to buy their special crimper and may have to splice into a longer wire anyway, are bulky and won't pass thru the holes in my solar-tracker mounts. But in some cases it makes sense to use it. For you it might be best to use the included MC4 with the optional extra cables for convenience and supposedly good waterproof connections.

Use an online wire sizing catalog for solar and all your wiring according to what you feel is acceptable voltage drop. At the following link you'll see for example that 5 amps through 20 feet of 12 AWG wire gives under 3% voltage loss. I like to keep it under 3%.

http://www.freesunpower.com/wire_calc.php#startGrn
vanguard64
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Re: Solar tracking mount

Post by vanguard64 »

I have looked at how the engine alternator, battery switch, and batteries are connected. I found this out sorting through historical papers provided by the previous owner. The work was done by an electrician at his boatyard in 2011. There is a smart battery isolator that ties the tow batteries together. The isolator treats one battery as the starter and the other as the house. If the voltage is 13.7 or above, alternator working, it allows the house battery to be charged also, but if the voltage drops to 12.7 or lower, it isolates the batteries to prevent the house battery from depleting the starter battery. Now my question is what effect would the voltage from the solar panel have on the isolator. It seems it would keep the batteries connected all the time when the solar panel is working with or without the alternator running. As previously mentioned, it may be best to switch the panel off when the engine is running so as not to confuse the regulator on the alternator or the isolator. If so, what kind of switch is best to use for cutting off the solar panel. I assume it would be placed between the panel and the controller.
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Re: Solar tracking mount

Post by atomvoyager »

I doubt the solar output going to the house battery terminal will cause a problem for the isolator. You can use any fused switch or circuit breaker rated for the solar panel amperage.
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Re: Solar tracking mount

Post by vanguard64 »

I am ready to purchase a rigid monocrystalline 50w solar panel. As I look around at different brands and vendors, I see a big discrepancy in price between those you can purchase on Amazon and those that are sold by marine solar panel vendors. Is there a distinction to be made between RV or land based solar panels and so called marine grade solar panels? Any suggestions on brands?
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Re: Solar tracking mount

Post by atomvoyager »

I don't believe there is any "marine" standard on solar panels so it may just be marketing terminology and can mean anything. I've always bought common brands based on the size I need and cost such as Renogy 50 Watt 12 Volt Monocrystalline ($75) from amazon or other similar panels from solar suppliers such as Arizona sun and wind https://www.solar-electric.com/
If you are still looking for higher voltage output then ask them what's available or if they think it's useful. Maybe someone here has an idea of better features that a marine panel could have or other models they prefer such as semi-flexible that are better to mount on dodgers or biminis or other curved surfaces.
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