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Old 27-01-2015, 08:57   #1
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how much solar

I acquired a Morningstar 60 amp MPPT charge controller. I have a 1000 amp battery bank. How much is solar panel can this controller handle. It seems simple enough 60 X 12 = 720 watts. Is that it? I have a large hardtop with a lot of flat area
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Old 27-01-2015, 09:01   #2
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Re: how much solar

Since solar panel wattage is quoted at open circuit voltage (around 20 volts) the controller will actually handle a bit more, around 1200 watts.
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Old 27-01-2015, 09:08   #3
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Re: how much solar

Best to go to Morningstar site and see if they have a sizing tool.
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Old 27-01-2015, 09:27   #4
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Re: how much solar

I find that using 15 watts per amp seems to get me in the ballpark quite close to the calculators so 60 amp morningstar would be about 900 watts of panel for a 12 volt system String Calculator ยป Morningstar Corporation
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Old 27-01-2015, 09:36   #5
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Re: how much solar

60 amps is the max output current at any voltage to its upper limit. As you have a 12 volt system which charges at about 13.5 - 14.4 volts

13.5 x 60 = 810

If you have too many input watts (ie. too many big panels) most good chargers will output up to their limit, in this case 60 amps and waste any excess. I would think 1000 watts of solar would not be unreasonable as it would be very rare that you get rated power from your panels.
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Old 27-01-2015, 09:37   #6
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Re: how much solar

Will it damage the controller if overloaded?
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Old 27-01-2015, 09:43   #7
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Re: how much solar

Not likely. Most controllers have built in cut offs. Check the manual. Best to go too much solar as it will rarely reach maximum input
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Old 27-01-2015, 09:43   #8
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Re: how much solar

Should not damage the controller as long as you do not exceed the max voltage, but too many input watts would just be a waste as the charger would not use them. The charger will produce no more 60 amps output regardless of any excess input. You could have 5000 watts available but it will use only what it needs to provide 60 amps out.
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Old 27-01-2015, 10:15   #9
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Re: how much solar

So 900 amps would be safe and get me close to 60amps in full sun in south florida?
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Old 27-01-2015, 10:19   #10
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Re: how much solar

I just installed 452 watts (4x113watt) of panels on my hard top, wired into a Tristar MPPT-60. Roughly half of my panels are shaded throughout the day due to the boom. New install, so I've only been able to monitor two days of use, but I averaged 75ah/day on mostly sunny January days in Florida.
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Old 27-01-2015, 10:29   #11
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Re: how much solar

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Originally Posted by motion30 View Post
So 900 amps would be safe and get me close to 60amps in full sun in south Florida?

In perfect conditions yes 75 Deg out full sun at 90 deg to the panels at noon, but I would not count on that, think 1000 - 1200 watts would bring you closer to 60 amps. Do you really need that much though, that's a lot of power for a boat?
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Old 27-01-2015, 10:38   #12
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Re: how much solar

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Originally Posted by motion30 View Post
I acquired a Morningstar 60 amp MPPT charge controller. I have a 1000 amp battery bank. How much is solar panel can this controller handle. It seems simple enough 60 X 12 = 720 watts. Is that it? I have a large hardtop with a lot of flat area
If you increase the number of panels, you may want to get another controller, as that will be your limiting factor.
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Old 27-01-2015, 10:46   #13
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Re: how much solar

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60 amps is the max output current at any voltage to its upper limit. As you have a 12 volt system which charges at about 13.5 - 14.4 volts

13.5 x 60 = 810

If you have too many input watts (ie. too many big panels) most good chargers will output up to their limit, in this case 60 amps and waste any excess. I would think 1000 watts of solar would not be unreasonable as it would be very rare that you get rated power from your panels.
This is the correct answer if your battery bank is 12v, if it's 24v then the answer is 1600w.

He also makes a very good point about not getting full power out of solar panels most of the time. I just installed two systems using this 60 amp MPPT controller and both have 3 x 230w panels for a total of 690w. Since the controller is capable of taking up to 150v input, I connected them in series even though I used 8 ga cable to the controller.

Here at this latitude, we saw a max. of 20 amps out of a max. possible of about 45 amps (690w = ~ 45 amps) due to the sun's low position in the sky. We'll see much closer to 45 amps in the summer. This will probably work out fine for these guys.

I also agree that it's not harmful to exceed the max wattage since the controller will self regulate at 60 amps. Just make sure that if you decide to connect in series or 2 sets of series strings that your Voc doesn't exceed 150v, that will kill the controller.

If you have the space for 1000w of panels, go ahead. You'll get a lot more out of the system winter and summer, with a max. of 60 amps. in summer if you even draw that amount. My 2 customers who were only getting 20 amps had fully charged 660Ah banks by 9:30 am, even though we were only seeing about 14-15 amps for just a few hours. We had to put a massive load on the system in order to draw the batteries down enough at noon to see the system put out 20 amps.

You will probably enjoy having all of that power available, just reschedule your big power draws for daytime operation, like watermaker, etc.

I only have 475w on my system, but I was constantly seeing fully charged batteries from 9am on, so I bought a portable ice maker that cranks out 20 lbs of ice during a 10 hr day and I shut it off and dump the excess ice into the ice chest every evening. Even with that load, the batteries are still topped off.

It's so nice having ice right there where I want it without having to open a freezer or cooler!
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Old 27-01-2015, 12:13   #14
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Re: how much solar

"How much is solar panel can this controller handle. "
Well, you can d*** around for a while, or you can look up the manuals and specs for it on the Morningstar site. There will be an exact answer from them, and the odds are it will be the correct one.
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Old 27-01-2015, 12:35   #15
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Re: how much solar

[Q UOTE=hellosailor;1734682]"How much is solar panel can this controller handle. "
Well, you can d*** around for a while, or you can look up the manuals and specs for it on the Morningstar site. There will be an exact answer from them, and the odds are it will be the correct one.[/QUOTE]
Actually that was the first thing i did and it left me a bit confused. ,it seems they use a lot Of abbreviations and terms that I simply do not understand. I now have a more clear picture of what I need
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