Blue Solar MPPT 100/50 low output?

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geep asked Jul 25, '19

Blue Solar MPPT 100/50 low output?

Recent purchase of this controller and two 170 Zamp panels. Hooked up first one, showed 65 watts, 20 volts, charging two lead-acid batteries in parallel. Added the second panel, and no change in wattage. I'd expected it to double. Panels wired in parallel for 12 volt system. Tried another battery that was completely discharged with similar results. I don't understand why the power level did not increase with the second panel, unless the controller is limiting not only the voltage to the appropriate level but also regulating current to a level appropriate for the battery load. The app was showing a bulk charge rate of about 4 amps. New to solar, trying to learn! Thanks

battery charging

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mattsmith answered · Jul 26, 2019 at 10:49 AM

I had similar issues. AGM batteries wired in series and parallel. 24v and 320amps with four 230w panels. Highest charge rate I saw was 600w changed wiring etc, nothing helped. Finally replaced the batteries with LifePo4 and bingo, full charging rate achieved. It was the batteries ability to take the current causing the limit.

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geep commented · Jul 26, 2019 at 01:51 PM

I hope I will see the same. I've been testing on marine batteries, and wondering if the charger was limiting the current output. You've confirmed that may be the case. Getting ready to finish the installation, and I will report back with how the system works with parallel wired panels and the LiFEPo4 Battle Born batteries. I've read the comments on series wiring the panels as well as done some more research, and have found that the MPPT equipment does function differently from PWM modules, making series wiring more attractive. I will continue to experiment. Thanks all who have answered.

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mattsmith geep commented · Jul 27, 2019 at 04:09 AM

I also run a Victron balancer, IMHO cheap insurance for expensive batteries. :)

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geep mattsmith commented · Jul 27, 2019 at 06:19 PM

Finished my install yesterday evening, and put the panels in line this morning, charging the LI batteries. I saw about 250 watts being produced from the two panels in parallel, before dropping off to an absorption charge and then going to float. The bank was fully charged by the Xantrex charger/inverter, so wasn't surprised to see the rapid drop off of charging current. Your comment was right, it the limitation was the battery type. I am satisfied that the parallel wiring will meet my needs, though I may experiment with series wiring after returning from an upcoming trip -- Galax (VA) Fiddlers Convention next week. Thanks to all who commented.

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Modifications Space

Node Red Space

Answer 1 · 2019-07-25T14:42:33Z

Matthias Lange - DE answered · Jul 25, 2019 at 02:42 PM

Correct polarity? Can you check the PV-voltage?

You can wire the Panels in series, the MPPT 100/50 can handle up to 100V PV-voltage.

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geep commented · Jul 25, 2019 at 04:02 PM

Wiring is correct. I don't need higher voltage, they are in parallel to obtain higher current. I have a 200 amp hour LI 12 volt battery bank in a camper that I want to charge, need the higher current capacity to bring them back up. Thanks for commenting.

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geep geep commented · Jul 25, 2019 at 04:04 PM

And I am seeing 20 + volts on the panel side in the app, about what I expected for late afternoon sun. They are rated at 23 volts max. Just not seeing the current output I would expect, and suspect that the charge controller is limiting current.

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Matthias Lange - DE ♦ geep commented · Jul 25, 2019 at 04:33 PM

A higher PV-voltage don't change your charge current.

With the higher PV-voltage the MPPT will start earlier in the morning and charge longer in the evening.

Is the a fuse or switch between MPPT and battery?

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geep Matthias Lange - DE ♦ commented · Jul 25, 2019 at 08:01 PM

Panel cables are fused vat 15 amps. No switch or fuse between the charger and battery. There will be a switch when I get done as the panels will not be permanently affixed to the camper.

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solardude geep commented · Jul 25, 2019 at 08:17 PM

Wiring in series has many benefits with zero downsides. Watts are the product of amps x volts. Watts are the true measure of power. If you you raise your voltage by wiring in series, you will get less voltage drop(more efficient), better morning and evening charging, and will net you more watts total during the day.

Just because you have more amps, doesn’t mean you are charging faster. Voltage has to be factored in as well.

Maybe try each panel separately and see if they both work as expected. If they do, wire in series. You will be much better off that way.

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Answer 2 · 2019-07-28T16:42:50Z

geep answered · Jul 28, 2019 at 04:42 PM

As noted above, connecting the array to a lithium ion battery bank and putting in the correct settings cause the current level to do what I expected. I have the panels in parallel, and note that under heavy load, the voltage does drop way down. As several have suggested, serial connections could be a better, more efficient way to go, so I am going to experiment with that hookup and see what happens. However, I am able to charge the batteries as well as provide reasonable reserve to run DC circuits such as lighting, as well as AC loads with the Xantrex inverter and keep up with the solar charging no matter which wiring scheme I decide on. Thanks for the help.

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