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Old 18-04-2015, 00:50   #1
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Solar panels direct to batteries??

I have done the search thing but cannot find a clear answer to my question so help please.
My boat,Seawind 1200, is relatively new to me fitted with a shore power inverter charger,standard alternators and a Diesel generator and two I think 120 watt solar panels.
I am replacing the two panels with two new 200 watt units and maybe later next season adding the old 120s back in.
At the moment I cannot ,without major surgery trace the solar wiring beyond
The Mppt controller but it appears to go back into the standard original loom and definately not direct to the batteries.
So my question is can I wire the new panels via Mppt controllers direct to the battery.If I do this will that cause any or all of the other charging applications ie generator,alternators and inverter charger confusion when they are operated together.
Chris
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Old 18-04-2015, 02:03   #2
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Re: Solar panels direct to batteries??

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Originally Posted by Mirage Gecko View Post
So my question is can I wire the new panels via Mppt controllers direct to the battery.If I do this will that cause any or all of the other charging applications ie generator,alternators and inverter charger confusion when they are operated together.
Chris
That will be fine. Just make sure you have appropriate fuses or circuit breakers.
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Old 18-04-2015, 05:25   #3
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Re: Solar panels direct to batteries??

Thanks Noelex
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Old 18-04-2015, 06:32   #4
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Re: Solar panels direct to batteries??

You use the term "direct" to batteries, but then refer to the MPPT controller. You do NOT mean direct from panels to batteries bypassing the controller right (which would be a very bad idea), but via the MPPT controller correct?

Most models of controllers have manuals and wiring diagrams available online. All normally go "direct" from the controller to the battery except for circuit protection (fuse/breaker) in between.

You are adding significantly more wattage, what is the rating of your controller?
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Old 18-04-2015, 06:42   #5
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Re: Solar panels direct to batteries??

Yes, you can wire the panels direct, i.e., through the MPPT controller as Noelex said.

Appropriate fusing and switches (or breakers) would be:

1. between the panels and the MPPT controller, so you can cut them out of the circuit if desired; and

2. between the MPPT controller and the batteries, preferably located very near the batteries. ANLs or MRBF type fuses are indicated for direct connection to a house bank (they have a high 5,000A + interrupt rating).

Regarding the issue of interaction between the panels and other charging sources, yes, you'll probably have that issue. If needed, with the appropriate switches you'll be able to disconnect the panels so they don't fight with other charging sources.

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Old 18-04-2015, 07:04   #6
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Re: Solar panels direct to batteries??

If you want the simplest solution, and this is not a "bad" idea as stated above.

I wire my solar panels directly to the batteries without using a controller. Lots of people do this. 5 years with the same panels and batteries I still have power, and only need a gallon of rainwater a year for the batteries.

I don't recommend unless you have flooded batteries, and have a voltage meter to easily monitor battery voltage (preferably digital) also a bad idea if you have a lot of input power for a small battery bank.

Obviously this is not the most efficient setup (but neither is using flooded batteries) but it is arguably the cheapest and definitely the simplest, and unlikely to fail.
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Old 18-04-2015, 07:18   #7
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Re: Solar panels direct to batteries??

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.........
I wire my solar panels directly to the batteries without using a controller. Lots of people do this. 5 years with the same panels and batteries I still have power, and only need a gallon of rainwater a year for the batteries................
This is an excellent way to FRY YOUR BATTERIES, especially with high output panels.

NOT RECOMMENDED.....at least not by anyone qualified to work on marine electrical systems.

What's more, it's not necessary. Even for those with small systems, there are a number of small and inexpensive controllers which will charge your batteries safely (e.g., the Genasun series).

Bill

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Old 18-04-2015, 07:39   #8
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Re: Solar panels direct to batteries??

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If you want the simplest solution, and this is not a "bad" idea as stated above.

I did this in the very early days of solar when solar controllers were expensive and not very efficient. It can be done, but you become a bit of slave to watching the voltmeter unless your consumption is always higher than the output. It is also hard to get the batteries up to 100%.

To reach 100% the batteries need a reasonable time on float. Getting a battery at least occasionally to 100% helps its lifespan. Unfortunately the float voltage varies significantly with small changes in current. You end up turning on unnecessary loads to reduce the voltage to an acceptable level and in changing conditions it is a lot of fuss.

These days of cheap PWM controllers there is really no need. The exception is if the controller fails and you cannot quickly source a replacement. Bypassing the controller will give you some power from the panels and if you are careful this can get you out of trouble, but watch that voltmeter. If the panels are wired in series, this needs to changed to parallel.

If doing this in an emergancy be especially careful with higher voltage panels. Here the voltage can rise to levels where not only will batteries be damaged but equipment as well.
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Old 18-04-2015, 08:22   #9
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Re: Solar panels direct to batteries??

As long as the current mppt controller can handle the additional amperage why change anything beyond the controller to the batteries if it works the way it is why make it more complicated. Also eluding to comments I have seen recently about hooking the panels directly to the battery don't do it there is no need pwm controllers while not the best can be had for less than 20 USD ( we have a spare cheap controller on the boat) the time you will spend monitering everything just to keep from frying your batteries will far outweigh the nominal cost of a spare controller.
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Old 18-04-2015, 08:25   #10
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Re: Solar panels direct to batteries??

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This is an excellent way to FRY YOUR BATTERIES, especially with high output panels.
Somehow my batteries are working.
Quote:
[/SIZE][/B]What's more, it's not necessary. Even for those with small systems, there are a number of small and inexpensive controllers which will charge your batteries safely (e.g., the Genasun series).
How inexpensive it is to ship such a controller to sumbawa? Is this controller submersible? I had a cheap controller and it died very quickly from salt water. My boat is not dry and I don't need it to be. Will it survive a lightning strike? How many controllers will I have to buy when I could have used none? Did you consider the additional losses in power and wasted heat? Did you consider that a lot of the cheap controllers have inaccurate voltage regulators over temperature, and cut out when they shouldn't meaning they are worse than useless?


I don't recommend not using a controller for every case, but it is a viable option, and in some cases the recommended one. These so-called "qualified" people are probably not considering the following scenario:

You find 4 golf cart batteries some one else is throwing away because they have only 30% of their original capacity. You wire up 200 watts of solar panels directly into them. Now you can run your computer 24 hours a day plus small loads. More importantly can also run a rice cooker and electric fan when the sun is up. Total cost of system is $200. After a few years, you replace batteries with more free ones so long term cost is zero. What is a cheaper way to achieve this performance involving a controller?
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Old 18-04-2015, 08:32   #11
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Re: Solar panels direct to batteries??

Wiring directly (without controller) is OK when the panel is small compared to the battery.

It is also OK when the panels are big BUT then only when and if the the owner can control the charge (read disconnect at high voltage). This can be done. And I have done it. And it is not efficient. And it IS completely impractical. I would only ever do it again if we lost our controller.

Now what the OP wants is to wire the controller directly to the batteries. And as posters above explained, this is perfectly normal.

b.
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Old 18-04-2015, 08:39   #12
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Re: Solar panels direct to batteries??

Quote:
Originally Posted by boat_alexandra View Post
Somehow my batteries are working.

How inexpensive it is to ship such a controller to sumbawa? Is this controller submersible? I had a cheap controller and it died very quickly from salt water. My boat is not dry and I don't need it to be. Will it survive a lightning strike? How many controllers will I have to buy when I could have used none? Did you consider the additional losses in power and wasted heat? Did you consider that a lot of the cheap controllers have inaccurate voltage regulators over temperature, and cut out when they shouldn't meaning they are worse than useless?


I don't recommend not using a controller for every case, but it is a viable option, and in some cases the recommended one. These so-called "qualified" people are probably not considering the following scenario:

You find 4 golf cart batteries some one else is throwing away because they have only 30% of their original capacity. You wire up 200 watts of solar panels directly into them. Now you can run your computer 24 hours a day plus small loads. More importantly can also run a rice cooker and electric fan when the sun is up. Total cost of system is $200. After a few years, you replace batteries with more free ones so long term cost is zero. What is a cheaper way to achieve this performance involving a controller?
What I see here with your proposed scenario is that you are using the battery bank mostly as a buffer between the panels and your constant load a low cost pwm would still, be a good item to have to regulate the voltage spikes that may and will occur if nothing else to protect your computer and other electronics and as far as being waterproof place the controller in a location that would not be subjected to near constant immersion in water and if submersion is a possibility I would be more concerned about the batteries you do know that when fla batteries are subjected to sea water they die a horrible death and it makes large quantities of chlorine gas.
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Old 18-04-2015, 08:51   #13
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Re: Solar panels direct to batteries??

as longs as you go through the controller which will shut off the panels power to the battery when it is charged you are OK


I used to run direct to the batteries from the panel and the batteries over charged sulfated and I had to replace them
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Old 18-04-2015, 10:30   #14
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Re: Solar panels direct to batteries??

Do not hook up the panel direct to the batteries. It will overcharge and cook the batteries. You must have a working controller. It's a mistake we've learned the hard way.
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Old 18-04-2015, 12:02   #15
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Re: Solar panels direct to batteries??

Before dropping the folding green stuff for a couple of 120 KW solar panels, you may benefit from learning about the new 345 KW solar panels available for marina use. Nearly the same size the output from two of these panels is nothing short of remarkable. Info is available at SunPower 345W X21/345 Solar Panel, Mono/Black | ACOSolar.com. A system consisting of only two panels coupled with the Mustang MPPT/Charger is capable of restoring on average 255 amp hours daily in the tropics. For most sailing cruisers that fulfills the hunger energy needs of their boats. No need to crank the iron horse or her mate the jenny.

One learns quickly, that an MPPT is as critical if not more when it comes to solar panels and their ability to replenish amp hours to battery banks. Solar panels can be finicky in how they generate power (angle to sun, any shading to the panel itself even if only a small portion can greatly reduce energy generation. A well designed MPPT can rectify many of these issues when coupled with a similarly well designed charger. This link provides you with beneficial information of the current advancements in this technology and show how to significantly improve replenishment of amp hours to the yachts battery banks: http://www.amazon.com/Morningstar-TS...r/dp/B007NMVL7

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