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Old 30-12-2014, 16:22   #1
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8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

I've got 8 100 watt panels I just installed on the boat.

On the dodger, there are 4 panels, 2 on starboard, 2 on port, running fore and aft.
The pairs are connected serially (port 1 + port 2) and (starboard 1 + starboard 2) and then parallel to a bus bar before going into the 60A MPPT.

The bimini is the same.

I have shading issues, would I be better off running each pair off their own MPPT? If one set gets shaded does it really slow the rest of the array down? I'm fairly certain all my panels have bypass diodes, as I fried 2 of them already (wired the last 2 backwards! grr)

If I go to 4 MPPT controllers, do you run those off a bus bar and one heavy run? I wouldn't want to run 4 pairs of heavy wires to the batteries if I can avoid it.

I figure the panels are 5.6A, so I should go with 20A MPPTs?
10A: Tracer 1210RN+ MT-5 LCD meter: $79ea
20A: Tracer 2210RN+ MT-5 LCD meter: $112ea
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Old 30-12-2014, 16:27   #2
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

Shading shouldn't be a problem but go to the morningstar website and use their string calculator to determine if the controller is adequate. 800w into a 60A controller seems a bit borderline, but so long as the controller has over current protection built in it should be fine and I doubt your setup would ever achieve full capacity by the sounds of the panel layout.
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Old 30-12-2014, 16:35   #3
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

Quote:
Originally Posted by monte View Post
800w into a 60A controller seems a bit borderline
Is my math off? 5A * 8 = 40A?
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Old 30-12-2014, 16:42   #4
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

Funny. Everything I have read said shading should be an issue in this setup. Because each side is two panels in series shading one cell on one panel would significantly affect the output of both panels. From what I read that's why you connect panels in parallel in setups on boats. But I am no expert. Just repeating what I read.

I assume you went with cheap semi flex panels from your description. Did you bench test them separately? Quality control can be a big issue with these panels. You might have some duds in the mix if you didn't bench test.

On the controller it seems to me you are ok. 8 panels at 5.6 amps each is just under 44 amps and its a 60 amp controller. But someone with more knowledge might know better.


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Old 30-12-2014, 16:56   #5
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

http://www.morningstarcorp.com/string-calculator/
Just fill the details in here
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Old 30-12-2014, 17:10   #6
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

I have installed semi flexible panels, cheap types from ebay and have found very poor performance. You should do a short circuit test in full sun and measure amps of each panel. I have also found once the sun is it any angle the output dropped dramatically.

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Old 31-12-2014, 10:06   #7
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

I have 720 watts of panels (3 wired in parallel) on one bus. Did that because shading is a giant issue with panels. When one of my panels gets shaded it takes that panel to 0 but has no impact on the output from the other panels. If wired in series you can easily lose 90% output with a shadow the size of a hand on only one panel. The only benefit I know of for going in series is that you can use smaller (cheaper) wire.

I hit the current limit every once in a while on my 60 amp Morningstar MPPT controller so with 800 watts suspect you will do the same. Not often enough to worry about it and the rest of the time I get great output. Can tilt them and this also makes a big difference, especially in the US in the winter.

Love the Moringstar as you can download a bunch of data through the ethernet connection. i.e. I have put over 208,000 amp hours in the batteries since installed. Also tells you how long it gets into absorption and float modes every day.

Given that you will only see 800 watts for a fairly short time each day seems to me that you made some good decisions. Only question I would have is series vs. parallel wiring.

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Old 31-12-2014, 14:20   #8
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

Since MPPT controllers want to track a nice clean current/voltage curve, shading is a real problem.
If you really want to get the most from your modules, use four MPPT controllers. You can bus them all together on the battery side and run one large pos and neg directly to the batteries.
Use circuit breakers on the solar inputs and battery outputs at each controller. Din rail mount breakers can be used nicely.
Happy Charging
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Old 04-01-2015, 14:58   #9
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

With the boom amidships I typically have half the panels in the shade in the afternoon, and half in full sun.

Should I be getting 400W of solar then?

Right now I'm getting 12.6A / 167W to the batteries,
array voltage side is:
37.10 Voltage
4.6 Current
Sweep Vmp 37.10
Sweep Voc 43.35
Sweep Pmax 177 W

I guess I'm losing a lot because the sun is low and the panels are not tilted?
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Old 04-01-2015, 15:41   #10
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

I would still be suspect of the panels themselves. if you have a simple multimeter disconnect the panels and short them via the multimeter in 10A mode. You should measure 5.6A in full sun. I purchased a few that only gave 2.4A in full sun and was able to get my money back. My experience with flexible panels is they fall off very badly at any angle or with even slight shading if they give the claimed output at all. It would be a shame to purchase more controllers and it does not help.
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Old 04-01-2015, 17:14   #11
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

If you are getting 400 watts with sun on only 4 panels you are doing amazingly for this time of year. Can't emphasize enough how important shading is. A hand size shadow can drop a panel to near zero. If wired in series will drop the entire array.

My suggestion is to use a preventer to pull the boom outboard and get the shading off. I bet that will make much more of a difference than tilting. The way you describe it, you really only have 1/2 of the panels working.

Never a bad idea to check the output to see if you got what you paid for, but from you description sounds like the panels are OK. Remember, you will only get the spec output under ideal conditions, and even then only for part of the day.

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Old 04-01-2015, 17:41   #12
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

So I have 4 pairs of panels
Half the pairs are in the shade
The other half are in full sun
Are you telling me that if I disconnect the ones in the shade, I'd get more power? That they somehow bring down the other panels? I was under the impression that they would just contribute less, not bring them down as well.

I will test the panels individually to see if there are any bad ones. I tested 2 of the first batch I got and they performed to spec, so I was lazy and didn't test the other two.
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Old 04-01-2015, 20:34   #13
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

Depends how they are wired. If all are as one series then yes, the shaded ones are reducing the entire array, including the ones in the sun. If wired in parallel then the shaded ones will only impact themselves and the sunny ones should put out full power.

Sounds like maybe you have each pair of panels wired in series with the 4 pairs in parallel. If that is the case then a shadow on one panel will only affect its series mate and not the other pairs.

One of the easy ways to check shadowing affect with the Morningstar controller is to load MSView on a computer and check the PMax value with different shading scenarios. Can do the same just looking at the ams. but the PMax is actual panel array output without regard to other loads, etc.

Here ia another item for you. It is 9 PM here and I am generating a few amps just off the moonlight.

Bill
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Old 06-01-2015, 05:48   #14
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

Is my math off? 5A * 8 = 40A?
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Your math does not take into account voltage.

800 Watts ( Panel Output ) X 13.5 Volts ( Charging Voltage ) = 59.2 Amps ( MPPT Controller Output )

My Morningstar MPPT 60 is rated at 60 amp OUTPUT, with up to 150 volt input.

The max watts to a 60 amp controller running at 12 volts is 800 watts. If you run it at 24 volts, you can use 1600 watts of panels, as long as you don't go over 150 volts input.

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Old 15-02-2015, 15:15   #15
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Re: 8 X 100W Flexible Solar + Morningstar MPPT-60 did I make a mistake

Shading is a BIG problem

I have 3 250 W panels, each with their OWN MPPT ( from Victron)
The price for 3 small MPPT's was the same as one 3 times the size. Now I have redundancy, plus optimal output.

The MPPT's are real close to the batteries, and with a nice big cable tied into the house battery

I use the Victron ones, because they can communicate directly with their CCGX, which which will show me what each one produces, plus it is linked to the inverter and showing shore power use, and letting the batteries being recharged FIRST with solar, even when connected to shore. ( It just happened to fall in place when I was redoing the breaker panel, and found out that the shore power and battery meters on the panel were more integrated than this CCGC, which also emails me when something goes wrong.)
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