Using 1 FM60 and 3 FM80s in a system

Discussion about the FM100, FM80, and FM60 Charge Controllers

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anpombo
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Using 1 FM60 and 3 FM80s in a system

Post by anpombo » Wed Jul 29, 2020 9:57 am

Hi,

I'm fixing my solar system and planning on setting up as follows:

7,200w in solar panles - 18 paneles 400w trina solar mono perc http://www.jssolartech.com/wp-content/u ... E15MII.pdf
Controllers: 1 FM60 + 3 FM80 ( currently own 1 FM 60 and 1 FM 80 so i'll be adding 2 fm80s)
Mate 3s with Hub 4
Battery bank: 12 2v 2000a OPzV Narada Batteries https://www.tempelgroup.com/catalogos/e ... arada..pdf
inverters: I currently have 2 victron energy multiplus 3000w system is at 24V https://www.victronenergy.com/upload/do ... -US-EN.pdf

The daily consumption in watts is 10,200w
The system is designed with 2 days of autonomy
The solar resource at the site is 3.5 solar hours

Would I have enough amp energy in with the 4 controllers to charge the batteries correctly and could I connect 5 panels to each FM80 and 3 panels to the FM60?
Thanks for your help reviewing this design. I've included the links for the data sheets for all components of the system.

raysun
Forum Emperor
Posts: 2525
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Using 1 FM60 and 3 FM80s in a system

Post by raysun » Wed Jul 29, 2020 12:17 pm

anpombo wrote:
Wed Jul 29, 2020 9:57 am
Hi,

I'm fixing my solar system and planning on setting up as follows:

7,200w in solar panles - 18 paneles 400w trina solar mono perc http://www.jssolartech.com/wp-content/u ... E15MII.pdf
Controllers: 1 FM60 + 3 FM80 ( currently own 1 FM 60 and 1 FM 80 so i'll be adding 2 fm80s)
Mate 3s with Hub 4
Battery bank: 12 2v 2000a OPzV Narada Batteries https://www.tempelgroup.com/catalogos/e ... arada..pdf
inverters: I currently have 2 victron energy multiplus 3000w system is at 24V https://www.victronenergy.com/upload/do ... -US-EN.pdf

The daily consumption in watts is 10,200w
The system is designed with 2 days of autonomy
The solar resource at the site is 3.5 solar hours

Would I have enough amp energy in with the 4 controllers to charge the batteries correctly and could I connect 5 panels to each FM80 and 3 panels to the FM60?
Thanks for your help reviewing this design. I've included the links for the data sheets for all components of the system.
The PV arrays as specified will fit within the power handling limits of the charge controllers so no problem there.

The charging system could potentially generate 300 Amps current. Is the battery capable of accepting that amount of charging current? (If I read the specs correctly 0.1c (10H) to 0.2c (10H), so 200 - 400A should be OK.)
Last edited by raysun on Wed Jul 29, 2020 12:22 pm, edited 1 time in total.

provo
Forum Guru
Posts: 463
Joined: Thu Jul 27, 2006 4:34 pm
My RE system: Sixteen Evergreen EC-120
(4 strings, total 1920W)
Eight Rolls S-550 (2 strings, total ~800Ah @ 24V)
One FM80
One VFXR3524A
Hub 10
Mate3s
FNDC and Trimetric
Location: Sierra foothills

Re: Using 1 FM60 and 3 FM80s in a system

Post by provo » Wed Jul 29, 2020 12:21 pm

anpombo wrote:
Wed Jul 29, 2020 9:57 am

7,200w in solar panles - 18 paneles 400w trina solar mono perc http://www.jssolartech.com/wp-content/u ... E15MII.pdf
Controllers: 1 FM60 + 3 FM80 ( currently own 1 FM 60 and 1 FM 80 so i'll be adding 2 fm80s)
Mate 3s with Hub 4
Battery bank: 12 2v 2000a OPzV Narada Batteries https://www.tempelgroup.com/catalogos/e ... arada..pdf
inverters: I currently have 2 victron energy multiplus 3000w system is at 24V https://www.victronenergy.com/upload/do ... -US-EN.pdf

The daily consumption in watts is 10,200w
The system is designed with 2 days of autonomy
The solar resource at the site is 3.5 solar hours

Would I have enough amp energy in with the 4 controllers to charge the batteries correctly and could I connect 5 panels to each FM80 and 3 panels to the FM60?
Thanks for your help reviewing this design. I've included the links for the data sheets for all components of the system.
Your battery is 2000 Amp-hours (not amps), and 7200W of panels at 80% of STC would output 5760W, which would be 240A at 24V. That's a charge current of 12% of the battery capacity, which is good. So the array and the battery are reasonably balanced.

The panels have a Voc of 49V at STC, so five on one FM80 (they would all have to be in parallel), is 49V to charge a 24V battery, which is good. Five 400W panels is 2000W, which is the max for an FM80, so also good. Three on one FM60 (also in parallel) would be 1200W, and the FM60 is spec'd up to 1500W, so also good.

You would also want a properly sized generator to charge in lower sun, and also an FNDC battery monitor (or some other coulomb-counting battery monitor) to keep track of SOC accurately.

I'm sure others will have more to say, but it looks reasonable. Are you strictly off-grid, or hoping to sell power back to the grid?

raysun
Forum Emperor
Posts: 2525
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Using 1 FM60 and 3 FM80s in a system

Post by raysun » Wed Jul 29, 2020 12:30 pm

One other note - with that much charging power, be sure to bring the PV panel leads to a combiner box per controller fitted with the proper disconnects.

With 4 charge controllers feeding the battery a Ground Fault Detector/Interrupter circuit breaker is highly recommended between controllers and battery. This unit is ideal for the application: https://www.solar-electric.com/outback- ... eaker.html

As @provo mentioned, a quality battery monitor is a must. If you are happy with Victron, their 7xx series are good units.

pss
Forum Czar
Posts: 565
Joined: Mon Jul 24, 2017 8:40 am
My RE system: 8330 watts in three strings, Flexmax 60 x 3, Radian 8048A, GSLC load center, Mate 3S, Hub 10.3, FN-DC and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Using 1 FM60 and 3 FM80s in a system

Post by pss » Wed Jul 29, 2020 4:12 pm

Are you purchasing these batteries in the USA?

anpombo
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Posts: 6
Joined: Wed Jul 29, 2020 9:02 am

Re: Using 1 FM60 and 3 FM80s in a system

Post by anpombo » Thu Jul 30, 2020 10:55 am

Thanks @raysun and @provo for you quick and insightful replies.

To answer your questions: this system is completely off grid and there is a backup generator connected to the victron inverter/chargers. It is a Ford 4000w generator with 6000w peak.

@provo would it be possible to connect for each FM80 3 paneles in series, 2 paneles in series and then connect the two series in parallel? or would the series with only two panels reduce the performance of the 3 panel series? That way I would have 150v and about 18amps running through those cables.

Regarding the battery monitor, is there any ouback battery monitor that can be connected to the Mate3s that I already have?

thanks in advance.

anpombo
Forum Member
Posts: 6
Joined: Wed Jul 29, 2020 9:02 am

Re: Using 1 FM60 and 3 FM80s in a system

Post by anpombo » Fri Jul 31, 2020 9:52 am

raysun wrote:
Wed Jul 29, 2020 12:30 pm
One other note - with that much charging power, be sure to bring the PV panel leads to a combiner box per controller fitted with the proper disconnects.

With 4 charge controllers feeding the battery a Ground Fault Detector/Interrupter circuit breaker is highly recommended between controllers and battery. This unit is ideal for the application: https://www.solar-electric.com/outback- ... eaker.html

As @provo mentioned, a quality battery monitor is a must. If you are happy with Victron, their 7xx series are good units.
Thanks @raysun and @provo for you quick and insightful replies.

To answer your questions: this system is completely off grid and there is a backup generator connected to the victron inverter/chargers. It is a Ford 4000w generator with 6000w peak.

@provo would it be possible to connect for each FM80 3 paneles in series, 2 paneles in series and then connect the two series in parallel? or would the series with only two panels reduce the performance of the 3 panel series? That way I would have 150v and about 18amps running through those cables.

Regarding the battery monitor, a BMV 700 with a 500a shunt should work correct? the FNDC would be ideal, however its more expensive plus I'd have to buy the 10 port hub (I currently have only 4 ports). Or would you suggest making the extra investment to have everything displayed in the Mate 3s screen?

thanks

raysun
Forum Emperor
Posts: 2525
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Using 1 FM60 and 3 FM80s in a system

Post by raysun » Fri Jul 31, 2020 10:16 am

anpombo wrote:
Fri Jul 31, 2020 9:52 am

Regarding the battery monitor, a BMV 700 with a 500a shunt should work correct? the FNDC would be ideal, however its more expensive plus I'd have to buy the 10 port hub (I currently have only 4 ports). Or would you suggest making the extra investment to have everything displayed in the Mate 3s screen?

thanks
IMO, Installing the FNDC for its display capability on the Mate isn't enough of a benefit to justify the extra expense. The Victron display could be mounted beside the Mate and make easy reading of both. (The Bluetooth version will even display on your smart phone.)

If the site has internet connectivity, then the FNDC makes a good deal more sense, as the integrated display in Optics RE is extremely useful.

Also, the FNDC provides other functions for the charge controllers, such as global charger control, charge termination control and float coordination.

Global charger control can manage charge controller output when using both FM80 charge controllers and Victron inverter chargers simultaneously. (It won't control output from the Victrons, but will scale output from the FM80s to keep maximum charging current at specified limits.)

Charge Termination can be set by specifying Charged Return Amps (the target current at the end of the Absorb cycle). When the value is met, the FNDC will command the FM80s to exit the Absorb stage. This helps minimize the "wear and tear" of overcharging, and also the shortened battery life caused by under charging. (This could also be derived experimentally by watching the Absorb phase on the Victron for target Charged Return Amps - victron calls it Tail Amps), and noting the Absorb Time it took to reach the Amps limit. The FM80 Absorb Time could be set to the noted value. The Absorb Time may need to be adjusted periodically.)

Float coordination keeps multiple FM80s from going to sleep during the low current Float stage, so they are more responsive should loads demand more current during this phase.
Last edited by raysun on Fri Jul 31, 2020 10:26 am, edited 1 time in total.

provo
Forum Guru
Posts: 463
Joined: Thu Jul 27, 2006 4:34 pm
My RE system: Sixteen Evergreen EC-120
(4 strings, total 1920W)
Eight Rolls S-550 (2 strings, total ~800Ah @ 24V)
One FM80
One VFXR3524A
Hub 10
Mate3s
FNDC and Trimetric
Location: Sierra foothills

Re: Using 1 FM60 and 3 FM80s in a system

Post by provo » Fri Jul 31, 2020 10:24 am

anpombo wrote:
Fri Jul 31, 2020 9:52 am

would it be possible to connect for each FM80 3 panels in series, 2 panels in series and then connect the two series in parallel? or would the series with only two panels reduce the performance of the 3 panel series?
Yes, the MPPT function would optimize the power as well as it could, but the result would be lower total power than if all strings had the same number of panels (one, in this case).

anpombo
Forum Member
Posts: 6
Joined: Wed Jul 29, 2020 9:02 am

Re: Using 1 FM60 and 3 FM80s in a system

Post by anpombo » Fri Jul 31, 2020 10:26 am

raysun wrote:
Fri Jul 31, 2020 10:16 am
anpombo wrote:
Fri Jul 31, 2020 9:52 am

Regarding the battery monitor, a BMV 700 with a 500a shunt should work correct? the FNDC would be ideal, however its more expensive plus I'd have to buy the 10 port hub (I currently have only 4 ports). Or would you suggest making the extra investment to have everything displayed in the Mate 3s screen?

thanks
IMO, Installing the FNDC for its display capability on the Mate isn't enough of a benefit to justify the extra expense. The Victron display could be mounted beside the Mate and make easy reading of both. (The Bluetooth version will even display on your smart phone.)

If the site has internet connectivity, then the FNDC makes a good deal more sense, as the integrated display in Optics RE is extremely useful.

Also, the FNDC provides other functions for the charge controllers, such as global charger control, charge termination control and float coordination.

Global charger control can manage charge controller output when using both FM80 charge controllers and Victron inverter chargers simultaneously. (It won't control output from the Victrons, but will scale output from the FM80s to keep maximum charging current at specified limits.)
Awesome thanks. Yeah, I'm gonna go with the BMV700, there is no internet connectivity over there and we are talking about 500 usd for the FNDC vs 128 of the BMV.

Would be great to have all equipment talking with each other, but this has been a system that has been upgraded by sections, therefore this was not possible.

anpombo
Forum Member
Posts: 6
Joined: Wed Jul 29, 2020 9:02 am

Re: Using 1 FM60 and 3 FM80s in a system

Post by anpombo » Fri Jul 31, 2020 10:32 am

provo wrote:
Fri Jul 31, 2020 10:24 am
anpombo wrote:
Fri Jul 31, 2020 9:52 am

would it be possible to connect for each FM80 3 panels in series, 2 panels in series and then connect the two series in parallel? or would the series with only two panels reduce the performance of the 3 panel series?
Yes, the MPPT function would optimize the power as well as it could, but the result would be lower total power than if all strings had the same number of panels (one, in this case).
Do you think the difference between having one string vs. having the controller use the MPPT function be significant? The reason I'm asking is because For the existing controllers (1 FM80 and 1 FM60) the wiring is already done with a AWG 10 wire. Connecting them in one string will put my amps over 30 amps.

provo
Forum Guru
Posts: 463
Joined: Thu Jul 27, 2006 4:34 pm
My RE system: Sixteen Evergreen EC-120
(4 strings, total 1920W)
Eight Rolls S-550 (2 strings, total ~800Ah @ 24V)
One FM80
One VFXR3524A
Hub 10
Mate3s
FNDC and Trimetric
Location: Sierra foothills

Re: Using 1 FM60 and 3 FM80s in a system

Post by provo » Fri Jul 31, 2020 10:48 am

anpombo wrote:
Fri Jul 31, 2020 10:32 am

Do you think the difference between having one string vs. having the controller use the MPPT function be significant? The reason I'm asking is because For the existing controllers (1 FM80 and 1 FM60) the wiring is already done with a AWG 10 wire. Connecting them in one string will put my amps over 30 amps.

A "string" refers to panels is series, so your choices are 2 strings of different lengths on each FM80 (one with 2 and one with 3 panels), versus all 5 panels in parallel on each FM80 (ie, no strings.) And the MPPT function is used either way, but one way gives more power.

I don't know what the difference in harvested power would be for the two approaches -- probably someone else here has an idea.

raysun
Forum Emperor
Posts: 2525
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Using 1 FM60 and 3 FM80s in a system

Post by raysun » Fri Jul 31, 2020 11:08 am

provo wrote:
Fri Jul 31, 2020 10:48 am
anpombo wrote:
Fri Jul 31, 2020 10:32 am

Do you think the difference between having one string vs. having the controller use the MPPT function be significant? The reason I'm asking is because For the existing controllers (1 FM80 and 1 FM60) the wiring is already done with a AWG 10 wire. Connecting them in one string will put my amps over 30 amps.

A "string" refers to panels is series, so your choices are 2 strings of different lengths on each FM80 (one with 2 and one with 3 panels), versus all 5 panels in parallel on each FM80 (ie, no strings.) And the MPPT function is used either way, but one way gives more power.

I don't know what the difference in harvested power would be for the two approaches -- probably someone else here has an idea.
I would not mix strings of different capabilities if I could avoid it.

Also, a string with a Voc of 150V is dangerous for the charge controller. Over-voltage events - like clear, cold mornings; or cloud-edge effects; can easily drive the voltage much higher than the STC ratings, and damage the controller.

The benefit to higher voltage strings (within safe limits) is lower current from the array, reducing power loss in a given size wire and the number of wires into the combiner. (Using proper gauge wire also reduces power loss just as effectively.)

The MPPT function on the charge controller is "smart" about finding the optimum power for charging. However, it considers the array as a whole. If the stings are behaving differently (as they will if different panels are mixed) the MPPT point will likely change more rapidly than the controller can follow, resulting in more PV harvest loss.

For the mix of panels listed, it would be best to put the 5 in parallel. The others can be wired two (or three) in a series string as appropriate and attached to the other controllers with array limits < 4kW.

anpombo
Forum Member
Posts: 6
Joined: Wed Jul 29, 2020 9:02 am

Re: Using 1 FM60 and 3 FM80s in a system

Post by anpombo » Fri Jul 31, 2020 4:08 pm

raysun wrote:
Fri Jul 31, 2020 11:08 am
provo wrote:
Fri Jul 31, 2020 10:48 am
anpombo wrote:
Fri Jul 31, 2020 10:32 am

Do you think the difference between having one string vs. having the controller use the MPPT function be significant? The reason I'm asking is because For the existing controllers (1 FM80 and 1 FM60) the wiring is already done with a AWG 10 wire. Connecting them in one string will put my amps over 30 amps.

A "string" refers to panels is series, so your choices are 2 strings of different lengths on each FM80 (one with 2 and one with 3 panels), versus all 5 panels in parallel on each FM80 (ie, no strings.) And the MPPT function is used either way, but one way gives more power.

I don't know what the difference in harvested power would be for the two approaches -- probably someone else here has an idea.
I would not mix strings of different capabilities if I could avoid it.

Also, a string with a Voc of 150V is dangerous for the charge controller. Over-voltage events - like clear, cold mornings; or cloud-edge effects; can easily drive the voltage much higher than the STC ratings, and damage the controller.

The benefit to higher voltage strings (within safe limits) is lower current from the array, reducing power loss in a given size wire and the number of wires into the combiner. (Using proper gauge wire also reduces power loss just as effectively.)

The MPPT function on the charge controller is "smart" about finding the optimum power for charging. However, it considers the array as a whole. If the stings are behaving differently (as they will if different panels are mixed) the MPPT point will likely change more rapidly than the controller can follow, resulting in more PV harvest loss.

For the mix of panels listed, it would be best to put the 5 in parallel. The others can be wired two (or three) in a series string as appropriate and attached to the other controllers with array limits < 4kW.
Great. Thank you very much for all your help!

¡

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