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Solar Panel Upgrade


Bill j.

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This is probably for Jack, but all thoughts are appreciated.

I have 2 100W panels on top now and have just received one 140 W and 1 160 W panel. Any reasons why I should not parallel them all together?

 

Controller is a Morning star 30 A.

 

Happy New Year All.

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Vmpp looks to be 18VDC and Impp will be no more than approx. 25 A for the total circuit. I doubt that I will ever see that. The Panels are mounted flat. More realistic output will probably be in the neighborhood of 18A.

 

I'm too cheap to trade out the old panels (10 yrs old) for up to date panels. That's why I was wondering about the mixed wattage panels.

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Bill, if these are low voltage panels then you will not have an issue, as others have said. I cover both low voltage and high voltage situations like this on my website, along with some examples of each. The effect can be surprising, depending on the panel specs. It is in the "Wiring" section - Solar Array Wiring Considerations

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Thanks for the encouragement Yarome.

Thanks Jack,

 

I'll have a look at Jack's site today. Yes, they are 12VDC panels.

 

Reason for the upgrade is upcoming annual trip to Quartzsite and recent refrig replacement with a residential refrigerator. Two hundred watts of solar will not be enough for an extended stay.

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Bill, FWIW here's one more take from an old retired engineer. In a nutshell, YES it will work, NO its not how some purist or a seller of panels might recommend lol. Looks like a total of 500 watts (if I understood your post) which under ideal bright sun direct overhead may crowd your 30 amp charge controller but I don't see that happening to much or too often based on my roof top flat mounted panel experience. If I were in your shoes and already had those panels Id probably hook them all up in parallel and not worry, even though my engineers preference would be to use a set of matched panels and Id consider some sort of series/parallel arrangement to run 24 volts down instead of 12. GO FOR IT is what Id do, if you were starting from scratch you might do differently. PS I will have the same question for myself next spring when I plan to add another 200 or 240 watts to my existing 200, I may go with 24 volts down to reduce current and voltage drop.

 

John T Left Bushnell SKP later to Zolfo Springs SKP

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Thanks John,

Soon as it warms up here I will go ahead with the install as planned. I'm sure I will never see 30A from this system. I'll be very happy with an occasional 25A. No system is perfect.

 

We use to say "close enough for government work" but these days government work leaves a bad taste in my mouth.

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My...My.

 

Think I found some thin skin. Must be the time of year.

Let's see, I spent 20 years in the USAF, last several years as an technical inspector or contract monitor. Then spent the next 20 years as a government contractor for the US Army. Been on both side of the fence. I've seen good and bad. I have my opinions and others have theirs.

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To get back on topic, Jack, do you think those buses on that end solar panel will be challenged by the possible 20A to 25A passing through with all panels in parallel? I think I will change out the wiring to 6 gauge though.

Gonna spend more roof time than I figured.

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You have to make sure that any components you use to fabricate a solution can take the power. That is why doing a bunch of daisy chained panels is a bad idea.....the components are not rated for the power being fed downstream over the last few panels. It is much better to do home-runs back to a combiner for that reason.

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