My set up

[Steve Booth]

Hello all, I don't know a lot about solar but jumped in with both feet here is what I am running I am not sure if I hooked things up for the best performance or not.
I purchased 28 , 225 watt solar panels, two outback 80 charge controller, Schneider electric sw4048 inverter/charger, Schneider ac breaker panel, Schneider elec dc breaker panel, outback hub, outback mate, 2 midnight solar combiners and 8 30 amp breakers.
24 tel com 12-105F batts.

I hooked the panels up 4 to a string parallel and series my input is 72 volts (not sure if it would of been better hooked different like three panels to a run) I used #2 welder wire from the combiners to the CC/inverter and batts. Yesterday on a mainly sunny day I produced 22kwh I am hoping to power my home/garage with this system but right now I just got some cords running into the house powering 2 deep freezers ,2 fridges ,dehumidifier, entertainment system, and a couple garden lights. Seems to keep up but not sure how to adjust my absorb time or absorb end amps. Any tips or advice would be greatly appreciated. Cheers

[Rob Beckers]

Hi Steve,

That's quite the setup!
So you have 4 panels in series per string? The FM-80 charge controller has a 150V input limit, and that is for the open Voltage of the panels on the coldest day. Those 60-cell panels you have reach 37V or 38V at 20C, making 4 per string reach 150V at that temperature (and more as it gets colder). That dictates a maximum string length of 3 panels. Two panels per string is too few PV cells, and too low a Voltage, to properly charge a 48V battery bank, so 3 is your only choice. Making for 9 strings of 3, for a total of 27 panels, or add 2 more and you can do 10 strings of 3 panels.

The equation for absorb time is:

Time = 0.42 x C / Current

The time is in hours, and C is the 20-hour capacity of your battery bank. Current is the average current your charge controllers put in, and this is somewhat of a guess (as on a sunny day this is more than on an overcast day). I generally use a reasonable current value for when there's sun. What this equation represents is an amount of charge going back into the batteries to make up for what's lost at the point that bulk charging has been done (and a battery is at around 80% SOC), it has some extra build into it to make up for the losses while charging. The end result is that it reverses all discharge, adding just a little extra to be on the safe side.

End-Amps is an alternative to absorb time, and more accurate if you have a way to measure actual charge current into the batteries rather than just the current the charge controller is putting out (which goes to both charging the batteries and running the inverter). Generally a reasonable end-Amp setting is 2% of C, the 20-hour capacity of the battery bank. When the current into the batteries drops below that the batteries are fully charged.

It's better to err on the high side for absorb time, than to be too short. Overcharging a bit is not a bad thing (within limits) for flooded lead-acid batteries, all it does is use up a bit more water (keep in mind that at the end of absorb the charge current will have dropped to pretty low values anyway). Chronically undercharging due to too low an absorb time or end-Amps setting is A Very Bad Thing for lead-acid batteries. It leads to sulphating that's hard to reverse, and premature battery failure.

By the way, if your charge controller does not use a separate shunt to measure current in/out of the batteries than end-Amps measures current going to your loads when the batteries are full, not what's going into the batteries, and it may never terminate, or run for a very long time beyond filling the batteries. Not the worst thing, but you're probably better off with absorb time in that case.

-RoB-

[Steve Booth]

Thanks Rob, for the end amp figures.
I have 4 panels hooked onto each string hooked up 2 in series 2 in parallel running 72 volts. My system is all up and running was my first 24 hrs with no grid power.I may need another connext sw4048 to handle the heavy loads. I took a 110v away from my water heater to cut the wattage to around 800 from 3000w I will let it run all day see how hot the water gets. It is cloudy and raining today but we are averaging around 1700watts and with the hot water heater running on 1/4 consumtion we are using 1300 roughly constant.Here is a few pics.
My storage AGM's
http://i1086.photobucket.com/albums/j441/243deerhunter/WP_20160521_18_41_05_Pro1_zpsqgzvupie.jpg (http://s1086.photobucket.com/user/243deerhunter/media/WP_20160521_18_41_05_Pro1_zpsqgzvupie.jpg.html)
The good stuff
http://i1086.photobucket.com/albums/j441/243deerhunter/DSC_0591_zpslmzhionk.jpg (http://s1086.photobucket.com/user/243deerhunter/media/DSC_0591_zpslmzhionk.jpg.html)
Poor mans roof top install
http://i1086.photobucket.com/albums/j441/243deerhunter/DSC_0592_zpszdfgkdae.jpg (http://s1086.photobucket.com/user/243deerhunter/media/DSC_0592_zpszdfgkdae.jpg.html)
Cheers

[Rob Beckers]

Interesting system Steve!
So you're running two panels in series per string? Yours are 60-cell panels by the looks of them. That means you have 120 cells in series for your 48 Volt battery bank.

To properly charge a 12 Volt battery takes 36 PV cells; that is why you still see many 36-cell panels around, though nowadays they tend to be lower Wattage (we can get them up to 150 Watt). The Voltage from a PV cell is roughly 0.5 Volt, so that 36 cell panel would work at around 18 Volt. When it gets warm, in summer in the sun, that Voltage drops however, and that same panel will run just over 15 Volt. That happens to be the upper Voltage for a 12 Volt battery while charging, in particular if equalization is needed.

By extension, to charge a 48 Volt battery bank would need 144 PV cells, that's 24 more than you currently have (or about 6 Volt).

Now, your batteries look to be of the sealed kind. Are those lead-acid AGM? If so, they would need about 58.8 Volt absorb Voltage (before temperature compensation) to get properly charged. Luckily there is no equalizing for AGMs, so that's also the highest Voltage they need. The Maximum Power Point of a solar panel moves at around 0.5% per degree Centigrade, and at 25C it's right around 30 Volt. So, for two of those panels in series you're going to hit 58.8 Volt for the MPPT point when the panels warm up just a few degrees above 25C, and the warmer they get from there, the lower that Voltage drops (and I'm ignoring any Voltage drop of the charge controller).

The long and short is that I suspect you're going to be seeing much less current coming out of the panels as summer progresses and those panels get warmer. The charge controller will be forced to run the panels right at the "knee" where the Voltage is high and the current drops off steeply with increased Voltage. Now the warmer the batteries get, the lower the Voltage they need, so these two things compensate for each other to some extend, but batteries tend to not get all that hot (it's bad if they do).

Yes, two panels can generate just over 70 Volt, but that's at very little (or zero) current. Maximum output of those panels is near 60 Volt, and that drops as they get warmer.

That's why I mentioned needing 3 panels in series to charge the batteries.
For what it's worth...

-RoB-

[Steve Booth]

I will explain this one more time ..I have 4 panels per string 2 in series two parallel per STRING. It seems to charge at a pretty good rate I wondered what the best config is ,but so far this on the best day has made over 400ah at 6030 watts with 96 amps 25kwh. My panels hit 72 in the sun when its hot 68-67 when its cloudy ,maybe since they are hooked in series and parallel it make more volts and more amps? I scrolled back through the CC 35 days and the lowest volts I made was 65 and we had some serious rain and cloud in them 35 days. So you are saying I would make more power to charge my panels with more volts less amps?

[Steve Booth]

Sorry Rob just trying to grasp this, If it will work better I will change the config of the panels. But would like to be sure you understand they are hooked in series and parallel if this makes any difference.I have never seen it make less then 60 volts unless it is sleeping.

Can you see the pics I don't even see a link to them?

I went out looked at CC#1 , 9 days ago (outta 32) was the lowest voltage at 64 here is what it says
64vp 172AH 8.9KWH
58.3Ap 3,32kwp

CC#2
64vp 137Ah 7.2kwh
46.7Ap 2.67kwp

I also scrolled through the to a high voltage day and copied the numbers
CC#1
72vp 182Ah 9.9kwh
33.6ap 1.84kwp

abs 1:15
flt 2:52

CC#2
70vp 97ah 5.2kwh
21.2ap 1.23kwp

abs 2:34
flt 3hr
I am very thankful for the help I don't know nothing about this stuff me and a friend hooked it all up the best way we thought. And it has been working well but if there is a way to configure it better I will be on it.
Thanks for your time

[Steve Booth]

So after I read this a Cpl times , I am thinking the two panel in parallel don't add any volts? just amps? And thus is leaving my array 24cells short for a proper charge?
To make this system work proper it should as you said be 9 strings of 3 unless I can get 2 more panels and make it 10 strings.

Wow looks like I got more work to do, hoping you come back and tell me that the two in parallel add double the amps and a single voltage which is obviously a wish at this point.
Thanks much Rob

[Rob Beckers]

Steve, correct, parallel adds current, series adds Voltage.

Each panel makes about 37 Volt when it's doing nothing (zero current), connect the (+) of one to the (-) of another, and you're adding the two Voltages together. Now you have one series string with two panels, and about 74 Volt (still at zero current). Start drawing current from that string and the Voltage goes down a bit, each panel makes most power at around 30V, so the two of them make most at around 60V. The current coming out is the same Amps as for a single panel; putting panels in series increases the Voltage, not the current.

Putting multiple strings in parallel, connecting the (+) to the (+) and the (-) to the (-) doesn't change the Voltage, it doubles the current. Put 3 strings in parallel and you have 3 times the current of a single string.

The thing with two panels is that it's right at the edge of being able to charge a 48V battery bank. If the temperatures go the wrong way (warm panels, possibly cold batteries) they can't do it any more. It somewhat works for you because your sealed batteries don't use equalizing (purposely overcharging the batteries at a higher Voltage). A regular, flooded lead-acid battery bank of 48V needs about 63 Volt to equalize, and two 60-cell panels in series can't pull that, especially when they get warm. Your batteries top out at about 58V ... 59V, so there is slightly more room, but not much.

As I said, it's right at the edge, that's why 144 cells in series are needed to reliably charge a 48V battery bank. You have 60-cell panels, with 3 panels in series that makes 180 cells, plenty to get the job done. Your charge controller is an MPPT-type controller, it takes care of efficiently converting the higher Voltage of the solar panels to the lower battery Voltage.

One more thing: You can only put strings of equal numbers of panels in parallel. So, if you have strings of 3 panels they have to go in parallel with other strings of 3 panels. If you connect a string of 2 in parallel it will have a different Voltage from that string of 3.

Hope this helps!

-RoB-

[Steve Booth]

Yes it certainly does help, I will find a Cpl more panels and then reconfigure.
Is it possible to load one CC with strings in series, and the 2nd CC with strings in parallel?
If I hook 10 strings of three panels in series will this work? the flexmax has a max of 80amp and my panels have a Isc of 8.09 and a IMP of 7.53 thanks a lot.

[Rob Beckers]

Both charge controllers will need multiple strings of 3 panels; so 3 panels in series, and several of those series strings then get connected (combined) in parallel.

Each charge controller works independent of the other one. Normally you would set them up with the same charge Voltages and parameters.

You could have one charge controller with strings of 3, and the other charge controller with strings of 2. The effect will simply be that the one with the 2-panel strings will deliver less current as the battery Voltage gets higher and/or the panels get warmer. For the reasons described before.

So, for now, you could wire one charge controller with 15 panels, made up as 5 strings of 3 series panels. The other controller would keep its 12 panels as strings of 2, and 1 panel would not be used. That second controller would have a hard time getting the batteries fully charged, but at least you'd have the other controller able to provide the needed Voltage.

-RoB-

[Steve Booth]

Hey Rob thanks for the help, I reconfigured the panels this last week I am now running 3 home runs on one CC three runs of 3 in series and then 3 in series parallel on each home run. I am now running 108v open circuit voltage. The system is charging much better now ,I will be adding two more panels this week and hopefully 6 more panels next week for a total of 36 panels as now I am running 27 panels. one cc has three runs the other only has 2 and one of the two just has 3 panels an none in series. Yesterday I made 36kwh and 691 ah of power. Cheers

[Rob Beckers]

Good to hear that worked out Steve!
36 kWh is nothing to sneeze at. That's a serious amount of energy (more than I use in a day with my grid-connected house).

-RoB-

[Steve Booth]

A large family living on solar power is tough, with 5 girls and a boy we can consume some energy. Yesterday we made/consumed 30kwh today we will again use over 30.
All three days my CC'ers hit float around 4 pm I am hoping when I install the last 9 panels we will hit float earlier. This leads to another question. Is it possible to set the float level a volt higher? to keep the battery's at a slightly higher level when we hit the end of day. I realize I can set that but would it be hard on my battery's

[Rob Beckers]

Steve, what is the brand and type of batteries you have? Charge Voltages depend on the batteries, and setting them too low or too high can do real damage (and within the window of low/high that is allowable there are trade-offs when changing the Voltage).

I would have to know more about your batteries though before commenting.

-RoB-

[Steve Booth]

Things have been running pretty good here, I am gonna top off the array with 6 more panels to max the system. I will have 18 panels on each Charge controller I am running 30 now and in direct sun at the best time I am getting 6850watts at 121 amps. I am thinking of adding another connext sw4048 to piggy back the other one and give me 7600watts of useable power and 9600watts of power for 20 mins I thin k that will cover our needs a lil better.My batteries are telcom 100ah batts running 24 on 6 banks.Cheers

[Steve Booth]

Well the system had been powering our house up until nov2 just great. On Nov 2nd my Schneider electric sw4048 messed up I used the combox updated the firmware with no luck F1(ac under voltage) I had been in contact with Schneider and they said they would send me a combox for the firmware update *free* of charge as I didn't have one. In the meantime I borrowed a buds and did the update while on phone with the tech guy. He said something more is wrong with the system he would start a RMA order. Told me it would take 10 days to clear the boarder. The next day Schneider called and asked if they could update me to a xw 5548 and a mini pdp .I said of course so I cant complain about the customer service. Now I got the 5548 hooked up and it works well we just need some sun.. uped the battery bank to 7 banks of four making it a 700 amp hr storage.

Can someone tell me what would be the best way to hook up windmill to this system assuming I would need another charge controller. But how will the current Charge controllers know wha the battery stat is at if another C/c is working on the batterys? Can anyone recommend a C/c and a windmill system a 400 watt one would be decent. Thanks n advance .Cheers

[Rob Beckers]

Steve, most small wind turbines come with their own charge controller. It's no problem to have multiple charge controllers on the same battery bank. In effect, each controller sees only the batteries and doesn't know, nor care, what the other charge controllers are doing. Each controller just follows its own charge settings.

Generally controllers are set up so they all have the same charge settings (so all are doing the same step of the 3 or 4 stage charge process), sometimes different settings are used on purpose. For example, for off-grid systems with with a backup generator and enough solar to generally get the job done via solar PV, I would setup the charge controller for the generator to use a lower absorb Voltage, and very short absorb time. That saves lots of fuel, in the case of propane that translates to saving quite a bit of money.

For wind turbines that do not have a charge controller but connect directly to the batteries, a "diversion controller" is used. It looks at the battery Voltage and diverts energy away, to a dump load (water heater ect.) so the batteries follow the proper charge profile. Some of the more popular PWM charge controllers can be configured either as a regular series controller or a diversion controller.

Hope this helps!

-RoB-

[Steve Booth]

Any suggestions on trouble free wind turbines? most I have seen or herd of had troubles.

[John Szegda]

If your serious about wind energy, the Turbines I would recommend are the Enair Pro series (cor@draaistroom.net) and Bergy (Solacity). I recently installed the Enair 70 Pro. The Pro puts out tremendous amout of energy for it's size and is built like a Marine tank.

John

[Rory Prinsloo]

Wow that setup looks awesome , wish I had the Rands to scale up like that , I find that if you wire your pannels in Parellel it will be better , I live off the grid in the bush ( jungle ) lol , I have a small set up but running my fridges om. Gas , I have a 150 watt set up with the most AMAZing 40 year old panel that pushes out more Volts and amps than my new generation panel , its the ARCO Pannel model no 16-2000 , I have a small set up with 500 watt inverter just enough to run a laptop and a circular saw if I need to , I'm looking. At getting a ghost wind turbine for the nights as. Well as the over cast days , I have a lawn mower set up to a car alternator that I run at night to charge for about an hour cause I only have one 105amp deep cycle solar battery , plus I must add my house is made out of recycle material , I am building a palet palace for me family

[Steve Booth]

My system sure seemed to make a lot more power on the cloudy low light days when it was hooked 2 panels series two parallel on each string. With the three and three it is barely making enough to keep me charged could the 2 string system work better in the low light with more amps and less volts?

[Rory Prinsloo]

My system sure seemed to make a lot more power on the cloudy low light days when it was hooked 2 panels series two parallel on each string. With the three and three it is barely making enough to keep me charged could the 2 string system work better in the low light with more amps and less volts?

What was the watts and amp reading on your panels ?
Interesting to know

[Steve Booth]

The values of the panels is previously mentioned each panel is 225watt, I now have 36 of them up. Yesterday Feb 3/ 17 At the 49th made 328 amp hrs and 17.5 KWH of power with the system not bad for feb eh? I think with a lil wind help this will run my house free of the grid, Cheers