Average 260-300 watt peak output from 640 watt flat mounted array?

[C-Cat]

Is that normal at this time of year in Arizona? I don't have tilt mounts, but these results seem disappointing... only one time I have seen 450 watt total peak from this array and that was a few months ago while driving down a mountain with the sun hitting the panels at a steeper angle...

About the system: 2x2x160 watt panels (2 strings of 2 panels in series / parallel config) feeding into a Victron 100/50 MPPT Controller, charging 4x6v AGM (500 Amp hours at 12 volt total capacity). Charging amps are usually around 20 amps at 13+ volts and one time I saw it peak around 30 amps...

Again, does that seem normal or did I buy crappy panels?

-Chris

 

[RVtrek]

I can't speak to AZ at this time of year, but I have a total of 320 watts on my roof. The *only* time I ever see the full 320 watts coming in was while in Texas in the middle of the summer. I expect that getting half of your rated output on flat-mounted panels probably isn't too far off.

My only recommendation is to try to clean them from time to time, get the dust off of them. Also, if you have anything else on your roof (like an AC unit or a roof rack) that could be partially blocking the light getting to the panel, that can really hurt your results as well.

 

[jonyjoe303]

If your batteries are 50 percent or higher you won't ever get the max from your panels. As the battery gets full it will take even less amps.

But one thing I have learned from using lithiums is that by increasing the voltage of the controller, you increase the amp output also. On my 13.1 volt lifepo4, they shouldnt be charged at more than 14.6 volts but at that voltage the controller is only feeding them about 4 amps, if I increase the voltage to 15.5 volts, the controller charges at 10 amps. To me that was a very interesting discovery. Maybe it will work with lead acid also?

My ecoworthy 20 amp mppt controller connected to a 240 watt panel (lying flat) maxed out at 12 amps on a 102 ah agm battery. I always suspected the cheap mppt controller just wasn't as good as the namebrand controllers. But when I started charging a 11.1 volt 94 ah li-ion battery pack, I was actually seeing the controller putting out 15 amps and saw it max out for a few minutes at 17 amps (which is more than the 240 watts the panel is rated). Thats when I suspected that the battery actual voltage determines how much the panels will put out. The lower the battery voltage, the more amps it will charge at. My observations best to worst in charge rates, Li-ion 11.1 volt (15 amps) , lead acid 12.7 volts (12 amps) and lifepo4 13.1 volts (10 amps). 

I would check for voltage drop, what the actual battery is reading and what the controller is reading. On my system I have a .5 volt drop. So if the controller is set for 14.4 volts, with the voltage drop the battery is only getting 13.9 volts, which is almost float voltage. You might have room to increase your controller voltage and maybe get extra amps(watts) to your battery.

 

[highdesertranger]

how are you measuring the watts? what panels do you have? keep in mind the panels rating where determined in a lab(hopefully) not in the real world. highdesertranger

 

[C-Cat]

how are you measuring the watts?  what panels do you have?  keep in mind the panels rating where determined in a lab(hopefully)  not in the real world.  highdesertranger

The charging watts are calculated by the Victron Controller. It shows the voltage coming in from the array (usually between 33 and 41), charging amps and the voltage on the battery side. I noticed that when you multiply the charging voltage and the amps, you also get about the same watt reading. And yes, I understand the lab reference. The panels are 4x 160 watt Eco-worthy poly's ( http://www.eco-worthy.com/catalog/worthy-160w-polycrystalline-solar-panel-p-597.html ). Their data sheet is listing:

Rated power: 160W
Voc: 22.5V
Vop: 18.7V
Short circuit current (Isc): 8.57A
Working current (Iop): 8.04A
Output Tolerance: ±3%
Temperate coefficient of Isc: (010+/- 0.01 )%/ ℃
Temperate coefficient of Voc: - (0.38 +/-0.01 )%/ ℃
Temperate coefficient of power Voc: -0.47%/℃
Temperature range: -40℃to +80℃
Frame:Heavy duty aluminum
Kind of glass and its thickness: Low Iron, high transparency tempered glass of 3.2mm
SLA Battery Voltage: 12V
Dimensions (L x W x H)mm: 1480*668*35mm(57.8"*26.3"*1.4"))
Weight: 13.2KG

 

[jimindenver]

Here in Ehrenberg my 750w roof system has been low due to a combination of lower sun, dust from the ATV's and the fact that I haven't cleaned them in quite a while. I can clean the panels, get rid of the ATV'rs altho I hate picking them out of the Ecpys grill but I can not do anything about the angle of the sun. Luckily the big panel on the truck does tilt and it makes a world of difference.

 

[John61CT]

Are you measuring amps into the battery?

That rate is up to the battery and its state of charge, as it gets past 75% full amps accepted goes way down.

Put some heavy loads on when conditions are ideal, maybe 100A worth, ideally one you can scale up and down, see if the output goes up.

 

[frater secessus]

Is that normal at this time of year in Arizona? I don't have tilt mounts, but these results seem disappointing... only one time I have seen 450 watt total peak from this array and that was a few months ago while driving down a mountain with the sun hitting the panels at a steeper angle...

It will only deliver a crap-ton of power if there is a big load running or the panels are getting full sun during Bulk mode (and early Absorption).  Systems with lots of panel start generating power so early that they can finish bulk charging well before solar noon, preventing the owner from witnessing The Full and Rampaging Glory.

As John has said elsewhere, if you want to see what your system is capable of:

1. run it down to 50% DoD overnight
2. disconnect the panels
3. reconnect the panels at solar noon
4. behold the power

 

[C-Cat]

I understand the load concept. but I actually run my batteries down every night close to 50 percent. Right now it's noon, the charge controller shows 20 amp charging, 13.11 volts for the battery (the inverter panel also confirms that). I also run my inverter all day (working pretty much constantly on my computer) and its control panel shows 6-8% load, which as a 2000w inverter should translate to about 120-160 watt usage (my trusty Kill-a-watt meter shows about 120 watt usage for my computer and monitor, so the difference could be inverter losses). That and charging the batteries in bulk should be plenty of load. So at noon on this clear and full sunny day in Cottonwood, AZ I'm getting 13.11*20=262.2 watt from my 640 watt array... I'm still a bit puzzled by that...

 

[C-Cat]

I just ran the Microwave to heat up lunch... inverter shows 94% load (I guess this is quite an inefficient microwave, at more than 1500w ) and the amps from the charge controller went up to 21 amps, battery voltage dropped to 12.28, total watts from the panels still show 262...

 

[tx2sturgis]

Sounds to me like some lack of performance in the controller, but maybe not. 

We can guess and speculate, but if you really want to test those panels, you need to use a digital meter and test open circuit voltage and shorted amps during full sun, on each panel. 

Then you will KNOW if they are the problem or not.

 

[John61CT]

What are your charge profile settings? (post a screencap from the app)

What happens to V and A from the controller when isolated from all loads?

What model batteries?

 

[C-Cat]

Yeah, that's probably a good idea to test the panels individually... I think I might also invest in tilt mounts after all... the way they are mounted right now (with these simple brackets: https://www.amazon.com/gp/product/B06Y5QX9VX/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1 ) I can't even take them off the roof to angle them towards the sun for a proper test.

 

[John61CT]

There is zero shading of the panels right, not even twigs, leaves, burd poop?

I'd say check your connections as well as the panels, keep them clean of course and yes consider tilting.

Might also be worth seeing if you get more of an MPPT boost from highr voltage, putting all four panels in series.

I actually run my batteries down every night close to 50 percent.

How are you estimating that?

 

[C-Cat]

What are your charge profile settings?  (post a screencap from the app)

What happens to V and A from the controller when isolated from all loads?

What model batteries?

The battery model is 4x: http://www.fullriverbattery.com/product/batteries/DC250-6

 

[John61CT]

Do you ever get to Float before evening?

How about true 100% Full, looking at endAmps? Likely need shore charging for that right?

How old are the batts? Cycled daily?

 

[C-Cat]

There is zero shading of the panels right,  not even twigs,  leaves,  burd poop?

I'd say check your connections as well as the panels, keep them clean of course and yes consider tilting.

Might also be worth seeing if you get more of an MPPT boost from highr voltage, putting all four panels in series.

How are you estimating that?

I usually call it a night when the batteries read 12.2 - 12.3 volts (under my average 120 watt load). Once I turn the inverter off, the batteries usually read around 12.4 volt.

 

[C-Cat]

And yep, zero shading and I cleaned the panels yesterday thoroughly, didn't make much of a difference...

 

[tx2sturgis]

 I think I might also invest in tilt mounts after all...

Yeah I see all kinds of different numbers online for the drop in power production due to the 'angle of incidence' being high.

I saw some numbers around 50% loss when offset by 45 degrees. 

But, most everyone compensates for this, either by installing more panels, or tilting the ones they have.

 

[C-Cat]

I know the MPPT controller likes higher voltages, that's why I made it 2 parallel strings with 2 panels in series each...