Are my charge controllers obsolete?

Discussion about the MX60 Charge Controller

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stevetull
Forum Virtuoso
Posts: 91
Joined: Tue Feb 24, 2015 6:40 am
My RE system: FlexPower Two:
2 VFX3648, X240, 2 FM80, Mate 3s, FnDC, Hub 10
One array facing south at 30 degree tilt
One array facing southwest at 10 degree tilt
Total of 8kW
16 Fullriver AGM DC400-6 = 830Ah @ 48v
OpticRE: Paige cabin
Location: Near Bastrop Texas
Contact:

Are my charge controllers obsolete?

Post by stevetull »

The charging instructions for my FullRiver batteries say that my current should be set at 83 amps however I can only achieve 70 through my MX60s.
(415 Ah X .20 = 83 amps)
Will this be a potential problem, and should I replace my two charge controllers? If so will Outback FM80s suffice? Or go with Midnite Classic 150s to achieve the needed power? I seem to be having a hard time getting a full charge on my batteries.

Thank you.

-Steve
Mike Curran
Forum Emperor
Posts: 2271
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Are my charge controllers obsolete?

Post by Mike Curran »

With 2 MX60's in parallel you theoretically can achieve 140 amps charging current. Maybe I'm misunderstanding your setup.
https://smart.tigoenergy.com/p/pZXn7SZQyO45?date=2021-04-19
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
stevetull
Forum Virtuoso
Posts: 91
Joined: Tue Feb 24, 2015 6:40 am
My RE system: FlexPower Two:
2 VFX3648, X240, 2 FM80, Mate 3s, FnDC, Hub 10
One array facing south at 30 degree tilt
One array facing southwest at 10 degree tilt
Total of 8kW
16 Fullriver AGM DC400-6 = 830Ah @ 48v
OpticRE: Paige cabin
Location: Near Bastrop Texas
Contact:

Re: Are my charge controllers obsolete?

Post by stevetull »

Hi Mike. Yes I have two MX60s, but each of my arrays feed a charge controller and then both arrays and both CC's all work together to feed the battery bank.

-Steve
Mike Curran
Forum Emperor
Posts: 2271
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Are my charge controllers obsolete?

Post by Mike Curran »

Hey Steve - If your 2 charge controllers feed a single battery bank (same as my system, btw) then each can contribute up to 70A for a total of 140 - under ideal conditions, of course.

If you're trying to decide whether to upgrade to an FM80, for example, then I would base the decision on your array size - can your existing MX60's handle all the power your arrays can produce? If so, and you're unable to reach your target absorb amps then you really need a bigger PV array, along with a CC upgrade.

Judging from your PV specs, it looks to me like your MX60's are capable of handling all the PV you have in your system right now:

18×175W=3150W, at 48 volts that's 65.6A to your battery

12×270W=3240W, at 48 volts that's 67.5A to your battery
https://smart.tigoenergy.com/p/pZXn7SZQyO45?date=2021-04-19
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
stevetull
Forum Virtuoso
Posts: 91
Joined: Tue Feb 24, 2015 6:40 am
My RE system: FlexPower Two:
2 VFX3648, X240, 2 FM80, Mate 3s, FnDC, Hub 10
One array facing south at 30 degree tilt
One array facing southwest at 10 degree tilt
Total of 8kW
16 Fullriver AGM DC400-6 = 830Ah @ 48v
OpticRE: Paige cabin
Location: Near Bastrop Texas
Contact:

Re: Are my charge controllers obsolete?

Post by stevetull »

Hi Mike.
I've ordered two FM80s to replace the two MX60s. To make the best use of the new CCs, do you think I should add a few more panels to each array? I believe at 48 volts the FM80s can handle 4000 watts each, whereas the MX60s max was 3200 watts. It seems I could add 5 more 175 watt panels to my south facing array, and 3 more 270 watt panels to my southwest facing array. If so, would I need an exact match on the panels? Or which numbers are the important ones? I'd imagine it would be difficult to get the same 175watt panel for my south facing array as they're 11 years old.
On that array we have 18 - 175 watt panels in six 3 panel strings filling up a six circuit combiner box. What's the best way to add 5 panels if I could find them?
On the newer array we have 12 - 270 watt panels in four 3 panel strings, and there's two slots open in that combiner box. Much easier to add the three additional panels.

Thank you so much Mike.

-Steve
Older panels
Older panels
Mike Curran
Forum Emperor
Posts: 2271
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Are my charge controllers obsolete?

Post by Mike Curran »

stevetull wrote:I've ordered two FM80s to replace the two MX60s. To make the best use of the new CCs, do you think I should add a few more panels to each array?
Definitely. If you don't add panels you won't realize any gain in power input to your battery, since your MX60's are already fully capable of utilizing your existing array's capacity.
stevetull wrote:It seems I could add 5 more 175 watt panels to my south facing array, and 3 more 270 watt panels to my southwest facing array. If so, would I need an exact match on the panels? Or which numbers are the important ones? I'd imagine it would be difficult to get the same 175watt panel for my south facing array as they're 11 years old.
I can tell you already know the answer. I don't know which numbers need to match. Pretty sure it's not just the ratings, the V-I curves for the new panels need to match the old ones. But if the Voc and Isc are close, you might not take too big a penalty, I really don't know. Maybe another forum user knows?
stevetull wrote:On that array we have 18 - 175 watt panels in six 3 panel strings filling up a six circuit combiner box. What's the best way to add 5 panels if I could find them?
You might want to get 6 new panels for a total of 24, then rewire your existing combiner for 6 strings of 4. Voc is certainly low enough for a 4 panel series string (~120V). You'll potentially be a bit on the high side power-wise so on sunny days your FM80 may limit (current) to your battery, but most of the time you should be okay, especially since your existing panels are probably derated from their age. You could put one of the new panels in each new 6 panel string, that might minimize MPPT losses due to mismatched panels. Sounds like a lot of roof work, though.

All speculation on my part. :grin: FWIW - Mike
https://smart.tigoenergy.com/p/pZXn7SZQyO45?date=2021-04-19
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
blackswan555
Forum Emperor
Posts: 2637
Joined: Sat Aug 30, 2008 5:50 am
My RE system: Other peoples, VFX "E" versions, FLA`s, Generators.
Location: Ibiza Spain,

Re: Are my charge controllers obsolete?

Post by blackswan555 »

What are your absorb voltages and times ? Do you have temp compensation and what are your daytime loads ? It seems to me that you may already have enough incoming PV but it is possibly not optimised for its best ?

Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.
stevetull
Forum Virtuoso
Posts: 91
Joined: Tue Feb 24, 2015 6:40 am
My RE system: FlexPower Two:
2 VFX3648, X240, 2 FM80, Mate 3s, FnDC, Hub 10
One array facing south at 30 degree tilt
One array facing southwest at 10 degree tilt
Total of 8kW
16 Fullriver AGM DC400-6 = 830Ah @ 48v
OpticRE: Paige cabin
Location: Near Bastrop Texas
Contact:

Re: Are my charge controllers obsolete?

Post by stevetull »

Hi Tim.
The charge controllers are set to bulk charge at 58.8v, absorb charge at 58.8v for another 4 hours, and float at 54.6. It may be that we had the absorb time set for only two hours. When you go into the MX60 menu, it seems to reset back to defaults or something, but anyway it was set to two hours. Perhaps that was a part of our problem and caused us not to get a full charge on the batteries.
We do have temperature compensation and an RTS installed.
Our daytime loads can vary since we may run small air conditioning, use the greenhouse exhaust fan during the hot part of the day, and run cabinet shop 120v circuits including shop lighting. We have several multiple circuit transfer switches so we can pick and choose what loads we will run on solar.
So to answer your question, during the summer in central Texas we can use 9kw at any one time during the day. I don't think I've seen our system bring in more than 5kw, so we're always making adjustments so that we can get the most use from our system but also to get as much charge on the batteries as possible.

Thank you Tim.

-Steve
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