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Brettny
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# Posted: 20 Apr 2021 06:08am
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Quoting: zorro So if I put the 3 panels in parallel (each PV = 46.6V/340W), total output voltage for all 3 should be 46.6V and should be around 1020W? If so, can I now use the EPEVER 60A MPPT Charge Controller with a maximum voltage of 150V Is that correct or do i need to go down the MidNite Solar Classic 150 MPPT route
The midnight 150 takes 150v input. The same as the EPever. You would need the midnight 200 if you wanted to run the pannels in series.
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zorro
Member
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# Posted: 20 Apr 2021 09:44am - Edited by: zorro
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ICC - that long response above is really helpful and explains a lot that even I can understand - thank you very much
Ok
Had a chance to read through this a bit more and think I have a better understanding thanks to all the help and patience from each of you – thank you
Needless to say, my “solar guy†is not answering my emails or responding t voice mails now that I have given him this level of information!!
Getting back to basics, it looks like there were 3 contributing factors to my battery issues, some bigger than others, but all adding up to an overall failure;
1 – panels wired in series and CC not able to deal with c. 170V output in the depths of winter – my “solar guy†or even the electrician who wired everything should likely have noticed this
2 – my Inverter does not switch off from the wall control and continues to draw power, unless you use the on/off switch in the unit itself – my fault and I should have read the manual!
3 – the AIMS battery charger draws power constantly, even when not in use – again, my fault and I should have read the manual!
So…… I think there are a few things I need to do;
1 – change the panels to PARALLEL wiring which will reduce Voltage output down to around 46.6V and maybe 56V max in winter
2 – add 3 x 15Amp breakers to the panels when I wire them in parallel
3 – add a breaker/marine breaker to the AIMS battery charger to stop the draw
4 – switch off the inverter from the unit itself
This should hopefully resolve my issues going forward
So for right now;
1 – install my new batteries (still awaiting delivery)
2 – check to see if the CC has blown, gone into “safe mode†or is still functioning……….maybe it literally shut down to save itself as it supposedly has; "short-circuit protection / high-voltage protection / overload protection" built in (we will see!!)
3 - if it is dead, then I need to get a new CC – I may actually get the same one I have as that has the following; max 150V (PV in parallel will resolve this issue), max Power = 2400W (in a 24V set up)
Either - PowMr & Srne 60A MPPT Charge Controller 60 amp, OR EPEVER 60A MPPT Charge Controller (both appear to have similar V/A max and minimums)
Have I missed anything or misunderstood anything at this point?
Thanks
Paul
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ICC
Member
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# Posted: 20 Apr 2021 10:06am
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Quoting: zorro 2 – check to see if the CC has blown, gone into “safe mode†or is still functioning……….maybe it literally shut down to save itself as it supposedly has; "short-circuit protection / high-voltage protection / overload protection" built in (we will see!!)
It occurred to me late last night that if the CC you have is as well designed and manufactured as the big names then that CC probably spent the winter shut down because the PV panel voltage was over 150 F.. If you looked at the Midnite Classic Tool and plugged in your panel data you would see that it calculates their Classic 150 would stop charging at a temperature of 37.4 F. If the temperature dropped lower than that and stayed there your system would not charge. So, if the hardware design and component quality good that CC may still work once connected to new batteries. You now know where the phantom current draws are and can be sure they are no longer a future problem.
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gcrank1
Member
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# Posted: 20 Apr 2021 10:37am
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You may luck out on the shut down and still have a cc, that would be Great and an endorsement for that product.
This looks like a good plan and a major step forward, though there always seem to be some loose ends and/or fine tuning to follow.
You've come a long way in a short time!
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zorro
Member
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# Posted: 20 Apr 2021 10:56am
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"You've come a long way in a short time!"
yeah - at one point I wasnt sure if the batteries would melt or it was my brain that would melt first!!
Still waiting on the new batteries, but as soon as i have them, i will head up to the cabin and see where i am at with the CC and let you know on here...........and then look at the "fine tuning" as gcrank1 states!!
Thanks again
Paul
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Brettny
Member
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# Posted: 20 Apr 2021 02:50pm
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If the CC dosnt work I would take it appart and inspect. They like to hide fuses behind covers.
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zorro
Member
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# Posted: 21 Apr 2021 11:18am
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Thanks Brettny
I did that at the outset of this issue and could not see any fuses other than 4 x 15Amp blade fuses, which were actually "stuck/attached" to the main mother board by what looked like a hard/white paste
Could not see any way to remove them without risking the motherboard
But again, thanks for the suggestion
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gcrank1
Member
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# Posted: 21 Apr 2021 04:13pm
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Did they look Ok? Usually the blown ones are obvious but by the time Im into something I just check em with my meter because Im OC that way.
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zorro
Member
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# Posted: 21 Apr 2021 04:22pm
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From what i could see they seemed to be okay...............and I just did not have a meter with me that day unfortunately
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gcrank1
Member
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# Posted: 21 Apr 2021 07:28pm
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I have my really good meter always with me in my rig but cheapies stashed at various 'critical' points where I tend to need/want to use one a lot.
And a notebook/pencil in my pocket most times. (memory aint what I remember it being....)
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zorro
Member
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# Posted: 21 Apr 2021 07:37pm
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Yep - lesson learnt!!
So my solar guy came back and confirmed he never gave the cold weather any consideration and agrees it could be a problem!!
So my stupid question of the day
I have 3 x 340w (46.8v) panels
I need to keep well below 150v for the CC
They are currently in series which is where this issue comes from
I know I can put them in parallel giving an output of 46.8v
Can I connect parallel and series - so connect 2 in parallel and then attach the 3rd in series giving around 94v?
Or I suppose I could get a 4th panel and have 2 banks of parallel giving the 94v
Just a thought and maybe stupid again!!
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Brettny
Member
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# Posted: 21 Apr 2021 07:56pm
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Quoting: zorro Can I connect parallel and series - so connect 2 in parallel and then attach the 3rd in series giving around 94v?
No you cant. This is why I brought up the number of pannels in a previous post. If you can get a 4th panel get one and run 2 in series and 2 in parallel. Typically this is called "2S 2P". Doing this would give you about 113v in cold weather and 380w per string with a total output of just under 1,400w.
You may find how ever that 3 pannels in parallel will work just fine for you as cloudy weather and 2 pannels in series act like one pannel In parallel. A cheap MC4 branch connector will give you many options and be able to test on site
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gcrank1
Member
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# Posted: 21 Apr 2021 08:18pm - Edited by: gcrank1
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Hmmm, my research has only indicated a 'balanced approach; ie, 2S/2P.
Just ran some math on the 46.8v of each in series again because I wanted to see the diff in these methods Ive seen variously used.
1) 46.8 x 3 = 140.4 + 20%(cold spike) = 168.48v
And an alternative way to est,
2)46.8 x 3 = 140.4 x 1.25 = 175.5
3) using a +25% factor would make 1) be 175.5 too.
Either way your, and many scc's arent in the 'zone', they seem to go to 150 then bump to 200, at a price.
For your next trip (and Ive done this way and you can do it without buying any more new parts yet):
Id discon the array from the scc (one lead is all you need to drop, Id do it at the array junction block where it becomes the 2 leads that go to the scc).
Wire your new bat-bank to the scc to see if it reboots
If so, it might be good to go.
Id leave 2 panels wired in series and discon the third one. With those two running into the scc it should start giving you charge; re-config if you have to from there.
With it up and working, or not due to a failed scc, you can chart your next moves.
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ICC
Member
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# Posted: 21 Apr 2021 08:18pm
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If you want to increase the total array wattage with one new panel to make a 2S2P string, the ideal would be to obtain another identical panel. That is sometimes difficult to impossible as panels are always changing. If an identical panel cannot be purchased there are some general guidelines.
For series connection – the same current rating of the panels is more important than voltage
For parallel connection – the same voltage rating of the panels is more important than the current rating
Use a 10% difference in either voltage or amps as the Absolute Maximum difference between panel ratings.
In effect with a SERIES connection, the panel with the lowest Amperage determines the maximum power that can flow from that series string. A 6 amp panel will drag the output of a 10 amp panel down to 6 amps, no matter how bright the sun.
Connecting panels in PARALLEL is the opposite. A 19-volt panel will drag a 30-volt panel down to a maximum of 19 volts when they are connected in parallel.
EXAMPLE: Let's say we have 4 panels; three are 19 volts 8 amp (19x8=152 watts max each). One panel is 16 volts and the same 8 amps. (16x8=128 watts). That 16-volt panel will drag the other panels down to a maximum output of 128 watts. That is a loss of 24 watts per panel or a total loss of 75 watts of power from the three 19 volt panels.
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zorro
Member
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# Posted: 21 Apr 2021 10:04pm
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As ever, excellent information guys - thank you
I am waiting to hear back from my solar guy who is supposedly speaking to the CC manufacturer about this issue to see if this is a common problem and if in fact, it would switch itself off before any damage occurs to the unit
He is also confident of getting me an exact same panel as i have if i want to go down that route
Will keep you informed
Thanks again
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Brettny
Member
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# Posted: 25 Apr 2021 08:15am
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Make sky blue controllers are just another cheap brand the could say MPPT but may not be MPPT. There is also word of fake chinese make sky blue controllers. I'm not sure what they gain by making a knock off of a chinese controller.
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gcrank1
Member
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# Posted: 25 Apr 2021 09:17am
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I have an 10yo? 'Blue Sky' Solar Boost 50, with this hyped 'sky blue' model Im thinking its the old bait on a similar name (sometimes mis-spelled)to suck people in?
Hey, it may be Ok. I'll,wait for it to be recommended on DIYSolar which has A Whole Lot More Credibility at this point.
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ICC
Member
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# Posted: 25 Apr 2021 10:11am - Edited by: ICC
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Those old "Blue Sky" were the first of the decent less expensive brands. These ones that are being loudly proclaimed to be the best thing since sliced bread are perhaps not in the same category. But even if these are good I do not like the guys attitude or the couple of doubtful claims he made. Sounds like the car salesman I walked away from years ago when he made a blatantly false claim.
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zorro
Member
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# Posted: 3 May 2021 11:30am
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Just a quick update
Was at the cabin on Saturday for a short time
It was a completely sunny day and panels were in direct and bright sunshine for several hours
• I fitted the Disconnect to the battery charger
• I placed the 8 new batteries (24V) into the system and turned on just the battery bank – CC quickly kicked on and recognized the 24V bank and showed correct levels at around 26.2 Volts
So that all seemed fine
I then turned on the Panels and again, that seemed to be working fine
So far, so good
Within 30 minutes, the Inverter alarm sounded showing “over voltageâ€
I then went out and removed 1 panel from the series connection, dropping it to 2 in series
That appeared to resolve the inverter and no other issues the whole weekend
So from this weekend, it appears to me that the system simply cannot cope with the output of these 3 large panels in series
The CC cannot cope and it seems the inverter cannot cope either with these 3 panels in series?
Once I get back up, I will put all 3 in parallel and see how that goes for the Inverter and CC
But from what I could tell, the CC seems to have survived the overcharge during winter and simply shut down
Does the above make sense.........or have i missed something?
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gcrank1
Member
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# Posted: 3 May 2021 02:06pm
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Think I would have done it that way. Sounds like you got lucky and the SCC internally saved itself, Wha-Hoo!
I like the idea of mppt c/w series, all indications are that it will, given good array exposure, pretty much always equal and likely outperform parallel.
The true test of system balance is how it all works; ie, your usage, the draw-down on the bat-bank and the recovery, initially for 24hrs then for up to 3-4 days. I would leave it as is and use it, monitoring as you go.
Fwiw, my pref for the bat-bank is to stay in the top 30-35% soc with only an occassional down to max discharge of 50%.
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ICC
Member
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# Posted: 3 May 2021 02:29pm
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If your Samlex has more or less the same specs as mine it likely states that the operating incoming voltage range is something like 22 to 32 volts. That allows for voltage drop due to heavy use and also allows the inverter to operate if lead-acid batteries are used AND the charger is performing an equalization charge. I used to have the inverter previous to the one you listed someplace here. The two are virtually the same. I often ran a equalization cycle and never had any high voltage issues with the EQ voltage limit set to 31.2 volts on the 24 volt lead-acid pack.
If your charger was not set to perform automatic equalization AND if you did not manually activate an equalization then that charge controller was somehow sending way too many volts to the batteries and that caused the inverter to fault.. IF the incoming voltage from the three PV panels in series reached the 150 volt CC incoming limit the CC should have shut off itself. The voltage from the CC to the batteries should never have risen high enough to hit the inverter maximum input voltage. Unless an EQ was started and the EQ voltage setting was higher than the inverter maxximum. Something seems wonky there.
Once you removed one PV panel from the series string and the system behaved itself is good. But that high voltage thing that occurred bothers me, makes me wonder just how reliable that CC is.
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ICC
Member
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# Posted: 3 May 2021 02:32pm
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Maybe check the spec sheet on your inverter to verify the low-high input voltage range of operation.
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zorro
Member
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# Posted: 3 May 2021 03:10pm
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Thanks guys
TBH, I never changed anything on the CC and let it do its business automatically
So maybe i need to look up on the "automatic equalization" process and figure out how to set that up, if it does not do it automatically
In terms of the Inverter, it states;
Wide operating DC input range: 21.4 – 33.0 VDC
So i really need to read up on the equalization process, but hopefully this at least allows the system to operate over summer
Now, stupid question of the day
(Each Panel - 340W/46.6V/Imp8.95A/Isc 9.53A)
Would I be better leaving the 2 panels in series "as is" = 93.2V/1251W......... I believe
OR
Better running all 3 panels in parallel, which we spoke about earlier in the thread = 46.6V/1250W.......... I believe
Clearly, 3 in series does not work for my system and i need to ensure i dont ruin these batteries and need a 4th set inside 2 years (my wife may actually kill me if that happened!!)
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Brettny
Member
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# Posted: 3 May 2021 03:27pm
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When you heard an alarm for overvoltage was it the the CC or inverter?
Its always better to have more pannels in the system so do 3 pannels in parallel. MC4 connectors are cheap and you alreaty own the pannels.
When I did my small 460w (two 230w pannels) I brought all the wireing together with a single run to the CC so I could run series or parallel by just un plugging and plugging back in.
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gcrank1
Member
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# Posted: 3 May 2021 03:37pm
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Set to 'operate over the summer'? Well, no. Not until you figure out the 'alarming' over voltage thing.
Eq doesnt need to happen often, so make sure you understand its function and why and maybe disable it on the next trip. Ease into getting familiar with the system then set up the Eq at some point. Imo it is not required at this point in your trouble-shooting.
Just letting it run and maybe needlessly cooking the bats would be....folly.
Btw, I have it on pretty good authority that a system, after all is said and done, will typically output 70% of the 'spec'. Armchair calc's aside, the functionality of your typical use to bat-bank reserve to recovery is the part that matters.
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zorro
Member
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# Posted: 3 May 2021 03:38pm
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The alarm was 100% the inverter, with a RED warning light to say Voltage Over Load
Based on the above posts, i actually bought the connectors and the fuses for a parallel connection - so they are all at the cabin
I just didnt get time to do that this weekend unfortunately
So 3 in parallel looks like the better option
It also hopefully solves the winter spike as well
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ICC
Member
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# Posted: 3 May 2021 04:09pm
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IMO, it is often better to NOT let a system do an automatic EQ charge. But manufacturers sometimes have a default of using an automatic EQ because that might be better for a system where the operator has limited knowledge. However, IF this CC has EQ set to automatic AND IF that is why the voltage got too high for the inverter, you can see how automatic things can cause problems.
But if your inverter operating range is 21.4 – 33.0 VDC and IF the DEQ voltage setting is what caused the inverter to trip, then the EQ voltage is set too high, IMO.
Lead-acid batteries do last longer with a periodic EQ. BUT only if they are flooded lead-acid batteries, not AGM. The best guide to whether or not a flooded lead-acid battery needs an EQ charge is to take cell readings with a hydrometer. That lets you compare all the cells state of charge and decide if they need to be equalized. Depending on what or where you read EQ voltage can vary from 2.5 to 2.7 volts per cell. A 24 volt battery will have 12 cells in a single string of cells to make the 24 volts.
Quoting: zorro (Each Panel - 340W/46.6V/Imp8.95A/Isc 9.53A)
That 46.6 volts is the Voc. The Vmp rating was given earlier as 38 volts. Do you understand the difference? Same question about the Imp of 8.95 amps and the Isc of 9.53 amps; do you understand the difference?
A rating of 340 watts per panel x 3 panels = 1020 watts total. Where is that 1250 watts figure coming from? It does not matter if the panels are connected in series or parallel, the total WATTS of the PANELS will be 340 x 3 = 1020 watts. The voltage and amps coming out of the three in series will be very different from the three in parallel though.
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zorro
Member
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# Posted: 3 May 2021 04:28pm
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Sorry - no idea where i got the 1250W
I was working on something else at the time and think i may have used that figure
I know i have 3 x 340W panels - sorry about that
I am reading the CC manual just now in equalization
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ICC
Member
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# Posted: 3 May 2021 05:06pm
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1250 watts may be the wattage limit of the CC at a certain battery bank voltage. That varies up/down with voltage (12/24/48)
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zorro
Member
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# Posted: 3 May 2021 05:33pm
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Max wattage on CC = 1600W/24V system
So should be okay with that
In terms of battery equalization - automatic every 30 days for 2 hours
There does look like there are a lot of parameters i can change in the menu.............but think i could cause more damage than cure!!
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