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Old 25-07-2015, 08:51   #1
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Solar wiring question

Ok, I have two separate systems on board (two controllers). One forward with a 100w panel and one aft with 2-100w panels. I am using Renogy panels and their MPPT 20A controllers, one for each location.

Now here's the question: They both feed into the house bank. Do the separate controllers see the increased system voltage of the other and say...hmmm looks like the system is up and I don't need to do anything? So does one of the systems shut down now? Or output substantially less since it thinks the system is up?

I have read that some people use seperate controllers for each panel. don't they get confused? Something like me?


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Old 25-07-2015, 09:52   #2
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Re: Solar wiring question

Two controllers like this do not generally cause any problems. If the parameters are adjustable it worth considering shortening the absorption time, especially if it is two hours, or greater.

If the parameters are not adjustable, just hook them up and worry about something else . They will play nicely together I promise.
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Old 25-07-2015, 10:04   #3
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Re: Solar wiring question

It might be helpful for you to to go back to basics: How batteries get charged 101.

1. Rising voltage as bank gets charged to a pre-set maximum voltage

2. Battery acceptance determines current

Any quality charger or regulator manual explains this in detail. Once you study it some more, you'll see that multiple sources charging a bank will all work together. Sometimes adjusting one of the parameters to be slightly different than another will provide a good solution.
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Old 25-07-2015, 12:12   #4
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Re: Solar wiring question

Thanks Stu. That is very concise explanation. But I have never seen it explained that way, and I read a LOT.
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Old 25-07-2015, 12:21   #5
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Re: Solar wiring question

Quote:
Originally Posted by seacap View Post
Thanks Stu. That is very concise explanation. But I have never seen it explained that way, and I read a LOT.
Maine Sail has been a proponent of adjusting the parameters for, for example, solar & alternators.

We both read a lot.
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Old 26-07-2015, 09:09   #6
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Re: Solar wiring question

no.. all they see is the battery voltage....

technically, due to the bulk/acceptance/float charge cycles determining the charge voltage & time applied and the logic decisions made by the individual chargers then there is certainly the likelihood of one charger being in its acceptance phase (say), and one in float (say), such that the two charging voltages are different, however they both simply see the battery voltage, not the charging voltage of the other charger, and the result is that one would be attempting to charge and one not.

There is no issue of any sort in this as it is the same as starting your engine while having the battery charger switched on.

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Now here's the question: They both feed into the house bank. Do the separate controllers see the increased system voltage of the other and say...hmmm looks like the system is up and I don't need to do anything?
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