FX80 compared to MX60

adas

Aloha, I notice a lot of difference between these two units, not just the 20amp more capacity. With the Flexmax80 the PV voltage is all over the map. (38v under some clouds up to 144v in direct sunlight. My MX60 stays fairly constant at 52 to 62 volts. Are there different technologies in these machines.

(BTW, yes I am dropping off one panel in the series to lower my VOC and will increase the amperage up closer to the 80 amp limit). I reason the voltage will over-volt at high noon when the batteries are at full charge, and is much less likely to over-amp with a weak sun in the morning even if the batteries are near dead....what do you think? (no I am not running the outbacks over-specs, just up to the limit.)


thanks
Frank

Solar Guppy

Re: FX80 compared to MX60

The Flexmax and MX-60 are different unit, the MX-60 is a sweep and sleep unit, most of the time, it will be stable and only vary when its sweeping the array. The Flexmax is advertised as dynamic tracking, so if it gets lost it would be all over the map voltage wise. I would suggest you call OutBack and get there take on what you are seeing ( maybe Crewzer has one and can chime in )

I haven't had one ( FlexMax ) to test out in person, but what you describe is either a bum unit or a poor mppt tracking.

What I have observed in general, is that so-called mppt units gets lost in partly cloudy weather, low current or High AC ripple operational conditions. I wouldn't be surpised it that was the case here, its very tricky to make dynamic tracking work in a charge controller, especially with high ripple current ( large inverter loads ).

To be clear I haven't put a Flexmax on one of my arrays/testbeds, so I am only giving general comments what I have seen in other, not-ready for primetime mppt units.

Unless one ends up on my door step for me to test, I'm not shelling out 650.00 to see if the unit performs under all conditions or loads as advertised.

adas

Re: FX80 compared to MX60

Aloha, I will call outback to be sure it is functioning correctly. The voltage rating does not jump around, as I may have implied, but drops down to say 45 from 120 or so then picks right up again. Maybe because of a cloud. But the MX60 pretty much stays around the VOC or a bit lower from dawn to dusk.

frank

boB

Re: FX80 compared to MX60

Is your battery full maybe ? The PV Voltage will go high when the battery voltage gets to absorb no matter which controller you are using.
What ~IS~ the battery voltage when this all over the map thing is happening ?

Beautiful day here in the NorthWest.

boB

crewzer

Re: FX80 compared to MX60

Adas,

As indicated, The MX60 and the FM80 are different beasts. But, they also have similarities.

The MX60 will generally hold its array voltage between periodic sweeps. However, during a sweep, the array voltage will vary widely as it typically sweeps between 90% and 50% of the array Voc.

The FM80 incorporates continuous dynamic MPP tracking, and it’ll hold the array voltage fairly steady during periods of uninterrupted Sun. However, during dynamic weather conditions, it’ll sweep up and down the array voltage to some extent as it looks for a new maximum value for the controller output current. This is known as a “perturb and observe” algorithm.

In general, I would say that sweeps from 144 V to 38 V (3.8:1) would not be common, and it could be an indication of system problems. The typical sweep limits are between 100% Voc and 50% Voc, for a 2:1 range. Also, the FM80’s upper operational limit is 145 V.

Could you provide us with more info about the PV array and the battery bank connected to your FM80?

HTH,
Jim / crewzer

adas

Re: FX80 compared to MX60

Aloha, I think much of my concerns have been answered. After initial charging the sweeps go from 140 to 80 or so and up to say 110 if there are some clouds or up to 130 or so if full sunlight. The MX60 only sweep periodically, so I guess it the voltage fluctuations are not noticable?
1: I am running my array "too hot" VOC calcs at 160volts, but the actual max reading is 146 on a sweep, so i am going to reduce by one panel in series. Currently I have 4 banks of 5 x 190W 7.12 panels. Going to 4 panels will bring me about 128 Volts.

2: I have to FX80's charging two sets of batteries. One set is 2 x 810AH in parrellel electric forklift batteries @ 24 V. The other set is 3 x 750 AH in parrelel electric forklift batteries @ 36V. I am charging them all up initially to see which ones are good. Then will replace the bad cells with a junk battery.

3: Do you think I can "overamp" rate the array, as 99% of the time the batteries will be over 1/2 charge and will never require full amps, AND when the sun comes up in the morning it will only trickle-charge the batterys until midday. (I know there will be a cold day when my batteries are almost dead and it is cloudy all day until noon when the sun comes out and bams overamps). OK stay within factory settings...

Frank

BB.

Re: FX80 compared to MX60

"Over availability of current" to the controller is a matter of proper safety design (fusing, wire gauge, controller rating)... But the controller will simply just use the maximum amount of current/power that is it programed to accept--and more panels/current will not cause the controller to accept more current.

Over voltage (Voc, Vmp) that exceed 150 volts will violate the warranty on the controller (I know the MX-60 will log over voltage on the panel inputs), and you run the real risk of destroying the charge controller too--or, at least reducing its life by over stressing it inputs.

I am assuming you are in the northern hemisphere (New York?)--and once it gets cold, you will definitely be in deep trouble (probably voiding your warranty--if you have not already, and when winter hits--you might damage your controller). Remember, Voc is pretty temperature dependent and increases as temperatures fall.

-Bill

VolcanoSolar

Re: FX80 compared to MX60

Naw, he's gotta be Hawaii -- unless they've started saying "aloha" in New York

- Ted

BB. wrote: »

I am assuming you are in the northern hemisphere (New York?)--and once it gets cold, you will definitely be in deep trouble (probably voiding your warranty--if you have not already, and when winter hits--you might damage your controller). Remember, Voc is pretty temperature dependent and increases as temperatures fall.

-Bill

BB.

Re: FX80 compared to MX60

Duh... H.a.w.a.i.i.

I was going by Ada's IP address which indicates New York City... Oh well... Still too close on the Voc... 1 volt below the Non-Operational point under load. And 6 volts below violating the warranty.

-Bill

PS: Looking at his sig with equipment configuration--now I remember he is in Hawaii...

adas

Re: FX80 compared to MX60

Aloha, I cut off a panel so down to 4 x 190 @ 128voc or so. Now to deal with the Amps. I have two FX80 and trying NOT to go into a 3rd. But you're right BB. .... here in Hawaii I will have to watch out for the over voltage this winter when the snow flies.
Frank

BB.

Re: FX80 compared to MX60

"...go ahead, make my day..." Adas. :cool:

I guess we can key people to our location by famous quotesin our text comments... Hmm a few more for my area:

"The coldest winter I ever saw was the summer I spent in San Francisco." Mark Twain "You are fortunate to live here. If I were your President, I would levy a tax on you for living in San Francisco!"
Mikhail Gorbachev

-Bill (near SF California)

crewzer

Re: FX80 compared to MX60

I notice a lot of difference between these two units, not just the 20amp more capacity. With the Flexmax80 the PV voltage is all over the map. (38v under some clouds up to 144v in direct sunlight. My MX60 stays fairly constant at 52 to 62 volts. Are there different technologies in these machines.

Warehouse System 4560w * Sun 24x190Wblems * 2xFX80's * 3 850AH 24v Batteries.(Used Forklift Type)

The voltage rating does not jump around, as I may have implied, but drops down to say 45 from 120 or so then picks right up again.

I think much of my concerns have been answered. After initial charging the sweeps go from 140 to 80 or so and up to say 110 if there are some clouds or up to 130 or so if full sunlight. The MX60 only sweep periodically, so I guess it the voltage fluctuations are not noticable?

I am running my array "too hot" VOC calcs at 160volts, but the actual max reading is 146 on a sweep, so i am going to reduce by one panel in series. Currently I have 4 banks of 5 x 190W 7.12 panels. Going to 4 panels will bring me about 128 Volts.

Aloha, I cut off a panel so down to 4 x 190 @ 128voc or so. Now to deal with the Amps. I have two FX80 and trying NOT to go into a 3rd.

Frank,

I believe that I now understand what is (was) going on. This isn’t an MX60 vs the FM80 (or any other charge controller) issue. The problem is (was) that the array voltage was too high as a result of wiring five Evergreen 190 modules per series string.

The STC voltage specs for five each Evergreen 190 modules wired in series are:

STC Voc = 32.8 V x 5 = 164.0 V
STC Vmp = 26.7 V x 5 = 133.5 V

Ref: http://www.evergreensolar.com/upload/195W_Product_Datasheets/S195_US_010408.pdf

The absolute maximum input voltage for the FM80 (as well as for the MX60, the Xantrex XW, and the Apollo T-80) controllers is 150 V. The MX60 and the FM80 both log the highest Voc applied, and exceeding the 150 V value could be an issue if warranty work is ever required.

The FM80 disconnects the array at ~145 V, and it will attempt to reconnect the array after the array voltage drops (i.e., when the array warms up). This is probably the source of the 146 V reading you reported.

With the array disconnected, the PV in voltage display will fall towards the battery voltage. This is probably the source of the 38 V value you reported.

Reducing the array configuration from five modules per string to four modules per string (STC Voc = ~131 V, STC Vmp = ~107 V) should work satisfactorily in your generally warm environment. The operational Vmp will likely be ~90 V to 95 V, and the array voltage during absorb and float modes will be over 100 V. The wide voltage range you observed should be eliminated.

The maximum power rating for the FM80 for 24 V battery applications is between 2,000 W STC and 2,500 W STC, depending on the codes and standards applied. 12 each 190 W modules would be 2,280 W, which is a tad high for the controller’s NEC spec.

There are three configurations for the 12 each Evergreen module array and a 24 V battery system: 4 (in series) x 3 (series strings in parallel), 3 x 4, and 2 x 6. The 2 x 6 configuration would operate at the lowest input voltage, which would allow the FM80 to operate at greater efficiency and therefore at lower internal temperatures. This latter configuration may be a good balance should you decide to go for the a 2,280 W STC array for each controller. However, it'll likely require heavier gauge wire than the 4 x 3 configuration

Check the 24 V battery system efficiency graph in the FM80 manual. Efficiency at 1,500 W from 51 V in is ~2% better than at 100 V in. That’s ~30 W less waste heat.

HTH,
Jim / crewzer

boB

Re: FX80 compared to MX60

crewzer wrote: »

Frank,

Check the 24 V battery system efficiency graph in the FM80 manual. Efficiency at 1,500 W from 51 V in is ~2% better than at 100 V in. That’s ~30 W less waste heat.

HTH,
Jim / crewzer

Aren't those the same efficiency curves as in the MX60 manual ? Nevermind this too... I see they are different. I do notice however that they are both labeled "input power". Isn't that really Output power though ? (both MX and MF)

Ya know... I don't see the MF80 manual on the new web site... (Nevermind, I found it there)

(Mudda-Fadda kindly disregard this letter...)

boB

adas

Re: FX80 compared to MX60

Aloha, All. So my conclusion.... If you are familiar with the MX60 and want to compare to the Flex80 display, don't, you will drive yourself crazy. Not even similiar.. Anyway that said, the display of the Flex80 does not give input voltage and battery voltage, it gives calculated input V/A and best output Amps at the highest Voltage according to the charging method you are on.
(I was lucky that I did not overVolt as the sky was a bit overcast and the max voltage only bounced the 145 barrier 3 or 4 times.) Log says I did 146.7 once. So it is OK. BTW I heard OB has driven the unit to 180V on test and not popped the triads, or whatever.

Right now the panels are at 115V open voltage (circuit breaker to the FX80 is off). As soon as the breaker is contacted the incoming (PV) voltage drops to 55V or so under load. (the mx60 keeps about the same voltage, more or less either under load or VOC). Point is that the first reading of V and A is NOT the actual panel voltage like it is with the MX60.

Either I have one helleva load on the batteries drawing the panels down or shorted cells, etc. We will see. But so far seeing the FX80 recalibrate, snooze,, wakeup, relate Volts to Amps, seems very logical and accurate. It just seems to do a lot of "thinking"
frank

crewzer

Re: FX80 compared to MX60

As soon as the breaker is contacted the incoming (PV) voltage drops to 55V or so under load.

Frank,

This is an example of normal operation for the FM80. When the breaker is closed and the array is detected, the controller will sweep ("perturb") from the array Voc down to ~50% of the Voc looking for the "maximum power point" ("observe"), which is defined as the highest output current value from the controller. The FM80 will then sweep back up the array voltage to whichever value corresponded to the highest output current value.

HTH,
Jim / crewzer

Solar Guppy

Re: FX80 compared to MX60

55V for an array with a VOC of 115V is much to low ...

A typical value would be about 88 volts for a vmp ...

Thats not P&O dynamic tracking, that's sweeping like the MX60 does. I'll assume the Flexmax also do performs some type of P&O dithering.

For comparison, the XW-60-150, does an instant on of about 78% of VOC and then only does dynamic tracking with a very small wattage pertrub, no full array sweeps, ever.

crewzer

Re: FX80 compared to MX60

Henry,

Hmmm... My previous post was not intended to suggest that 55 V was an appropriately typical Vmp for an array with an indicated Voc of 115 V, nor to suggest that the FM80 would operate that way.

Just to clarify: The 55 V value observed is probably the bottom of the controller's initial sweep (~50% of Voc value of 115 V). I doubt it's the operational Vmp, which I agree should/would be ~90 V.

Once the FM80 sweeps the array (from 100% Voc to ~50% Voc) to find an array voltage that corresponds to the maximum output current from the controller, it then returns to that array operating voltage and initiates its P&O algorithm, and it generally dithers from there.

Starting off at 78% of Voc is certainly another way to go. However, my experience with my array that is subject to occasional seasonal shading is that this approach could be less than optimal for my system. Specifically, with one module shaded in a string and bypassed, my array's Vmp will temporarily be but ~50% of the indicated Voc.

The FM80 takes a few seconds to find the array's actual Vmp and then operates from there. As a practical matter, I doubt there's any significant difference (in terms of energy produced) between the two approaches.

Regards,
Jim / crewzer

Solar Guppy

Re: FX80 compared to MX60

There are many what-if check's in the XW mppt's routines, partial shading, large changes in irradiance are just some of things continually evaluated

The %voc is for instant power on, nothing else

adas

Re: FX80 compared to MX60

aloha, and yes Jim, your previous post are what is happening. The FX80 seems to take some time "to figure it out". Now it is running at 93V intake and nudging up the output amps while trying to also boost the Voltage up to the absorb limits. It is only 9am now and I think I will see the absorb limit voltage reached soon and then the amperage building up according to battery needs. thanks,
Frank

adas

Re: FX80 compared to MX60

crewzer wrote: »

Frank,

This is an example of normal operation for the FM80. When the breaker is closed and the array is detected, the controller will sweep ("perturb") from the array Voc down to ~50% of the Voc looking for the "maximum power point" ("observe"), which is defined as the highest output current value from the controller. The FM80 will then sweep back up the array voltage to whichever value corresponded to the highest output current value.

HTH,
Jim / crewzer

The 55 V that I saw was near the end of the day (After 4:30 pm), so the FM80 was doing what it can with failing sun.
Frank

mike95490

Re: FX80 compared to MX60

Generic MPPT question: for any fixed array, does changing the harvest voltage minute by minute, really affect anything ? Say you set the MPPT voltage at mid day, and locked it there, does changeing it every time a cloud go over really help ??

What if the the fancy $ controller was replaced by a installer setpoint dip switch or jumpers, and left that way? (set while panels are "hot" from sun) Does varying the setpoint increase the harvest by any significant amount ?

Solar Guppy

Re: FX80 compared to MX60

Hi Mike,

yes, it does vary quite a bit over the day. Sun heats things up, wind cools things down, mounting locations ( like a roof ) further where the panels are mount will be more of a varation source. Clouds comming and going ( especially in windy conditions ) can have 4-5 volt per minute changes in the vmp ( 48V )

On a 48V nominal array 10-15V is typical movement for the vmp range over a typical day.

As to how much it effects harvest, gridtie, big time. Offgrid, depends totally on the batterys and charger type. With pwm controllers as the vmp drops, typically the charge voltage rises and closes the gap on the vmp to battery voltage.

adas

Re: FX80 compared to MX60

Aloha, OK now we are running at 95 volts in and today with the perfect sun at high noon, I got with dead batteries up to 72 amps each of the 2 FX80's. The calculation of the 3 banks of 4 190W panels is 85 amp. In Hawaii, I don't expect any cold winter weather to get more amperage, so will the FX80 overamp and record it and void my warranty?

thanks
Frank

crewzer

Re: FX80 compared to MX60

The calculation of the 3 banks of 4 190W panels is 85 amp.

Frank,

Can you help me understand where the "85 amp" number came from? It's pretty difficult to "overamp" the FM80's output, as the current limit setting in the "Charger" menu will limit output current from the charger.

HTH,
Jim / crewzer

adas

Re: FX80 compared to MX60

crewzer wrote: »

Frank,

Can you help me understand where the "85 amp" number came from? It's pretty difficult to "overamp" the FM80's output, as the current limit setting in the "Charger" menu will limit output current from the charger.

HTH,
Jim / crewzer

Aloha, Jim, your comment above kinda answered my question that it is difficult to overamp the FM80. The 85 amp is the calculated output of the 12 panels (7.12 amps each) in series that are on each bank for each FM80. Just as the voltage can be exceeded and void the warranty, I take it that the amperage will be trimmed by the FM80 and not exceeded? thanks

Frank

(looking at it again, I see it cannot be overamped as we are talking about the FM80 OUTPUT which I have no control over vs the Voltage INPUT that I have control over!)

BB.

Re: FX80 compared to MX60

MPPT charge controllers "control" their output voltage and current to the maximums allowed, and programed in.

The input current/power is therefore also controlled by the charge controller.

The NEC rules are, sort of, written as if the solar charge controllers cannot/do not control how much power they accept/output--which is dead wrong.

The major item that a charge controller cannot "control" is the Voc (Voltage Open Circuit)... If the controller decides to stop accepting current from the solar panels (say the batteries are fully charged), then the panels' output voltage will rise to Voc (based on sun and temperature)... If it is too high, it will stress and eventually cause the input electronics/switches to fail. Some manufacturers (Outback for sure) will log the highest input voltage for warranty purposes.

-Bill

System2

Re: FX80 compared to MX60

Hello,

The 85 amp is the calculated output of the 12 panels (7.12 amps each) in series that are on each bank for each FM80.

Surely this isn't accurate. If I'm think of the same Sun 190 blems that you own, they are spec'ed at Vmp of about 25v. 25v X 12 series = 300v, the absolute maximum array voltage of the FlexMax is 150v. Previously you stated:

The calculation of the 3 banks of 4 190W panels is 85 amp.

Hopefully this is the configuration of your array. If so, and I suspect this to be the case, you're not generating 85 amps with a 4 strings X 3 panel array configuration. You multiply the amps X strings and multiply volts X panels. Your 7.12A per panel in this configuration would be 28.48A at (3 series panels X panel voltage).

Cheers,

Bad Apple

Solar Guppy

Re: FX80 compared to MX60

Hopefully this is the configuration of your array. If so, and I suspect this to be the case, you're not generating 85 amps with a 4 strings X 3 panel array configuration. You multiply the amps X strings and multiply volts X panels. Your 7.12A per panel in this configuration would be 28.48A at (3 series panels X panel voltage).

Cheers,

Bad Apple

Well, for array amps thats correct, but for battery amps, takes the watts and divide by the battery voltage as the Mppt converts excess voltage into amps!

So 12 * 190 = 2280 watts @ 28V is ~81 amps. Now this doesn't take into account the charge controller losses, the voltage loss for heat ( lowers the watts ) and the irradiance which is typically ~930 watt/meter/squared ( panel is specs at @25C panel tempature @ 1000 wMsq

Figure 10% for heat, 6% contoller and 7% for lower irradiance

2280 * .90 * .94 * .93 = 1793 watts / 28V = 64 amps expected with all derating. You mention the batteries are dead, so lower the charge voltage from the above one gets 1793 watts / 24V = 74 amps

Sounds like its running perfect and your Evergreens are working at Nameplate peformance!

System2

Re: FX80 compared to MX60

Well, for array amps thats correct, but for battery amps, takes the watts and divide by the battery voltage as the Mppt converts excess voltage into amps!

Right you are, I was focusing on the "12 panels in series" statement and not the output amperage. That's the problem with a typed conversation vs. a face-to-face.

Cheers,

Bad Apple