diy solar

diy solar

System down. Please help!

Tbleppy

New Member
Joined
Feb 4, 2021
Messages
90
I have a solar off grid system consisting of 12 100w 12v mono panels which are set up 3s4p with an inline fus at each string, 50a circuit breaker(acts as disconnect switch), renogy 40amp mppt charge controller, goes thrpugh another 50a circuit breaker, 4 LiFeBO4 batteries 100ah 12v hooked up 2s2p, 150a class T fuse, 2000watt 24v samlex pure sine wave inverter all hooked together in that order. Then I have one hardwired outlet for appliances and I'm also utilizing the inverter plug ports too.

Everything has worked well. We just moved the panels to catch the winter sun. Then we get hit with storms and after a bunch of rain I notice no solar panel power is registering one morning. Not only that but our inverter is still on but the batteries have been drained to 0.5! They've been completly emptied! My charge controller is set to the correct parameters and will read 26.4 when there is plenty of sun, may read 25.5 if it's overcast. It drops to 24.3 at night somrtimes andcan go lower all the waydown to 21.5 and that's the max discharge it will allow before it beeps and the inverter gets shut off. I was shocked by what I saw.

This has never happened, but say I didn't hear the beeping for the shut down-would everything stay on until my batteries fully drained or would there be an auto shut down that would take place in the case I didn't manually do it?

Also, what could cause this to take place? Before going to sleep it read at 24.4 and I had no concerns because that is normal to see at nightime. Why on this night with nothing on but a fridge while we slept would my batteries be zapped down to nothing?

If I did sleep through the inverter beeping (or is it the charge controller that beeps?), would everything still continue to run until the batteries were at nothing? My previous inverter would kill the power at a certain point if it was not manually shut down. I presumed that would be the case with this one too.

My husband was concerned about the mc4 connectors being exposed in the rain during the setup. I told him they are waterproof. He took my word for it and I know I'm right but could rain cause this type of a problem and how? It was a heavy rain. When I went to check it out I noticed one of the connectors was submersed in a puddle. I removed it from the puddle. I also noticed at least a couple didn't look like they were fully screwed shut tight because I still saw some of the thread where you twist them shut.

How do we troubleshoot this? What do we do? Thanks for your help!
 
Everything has worked well. We just moved the panels to catch the winter sun. Then we get hit with storms and after a bunch of rain I notice no solar panel power is registering one morning. Not only that but our inverter is still on but the batteries have been drained to 0.5! They've been completly emptied! My charge controller is set to the correct parameters and will read 26.4 when there is plenty of sun, may read 25.5 if it's overcast. It drops to 24.3 at night somrtimes andcan go lower all the waydown to 21.5 and that's the max discharge it will allow before it beeps and the inverter gets shut off. I was shocked by what I saw.

0.5 means the battery BMS has tripped and cut off the battery due to being completely discharged.

24.3V is a very low state of charge.

21.5 is barely above empty.

Your batteries should be charged to AT LEAST 27.6V and likely over 28V.

This has never happened, but say I didn't hear the beeping for the shut down-would everything stay on until my batteries fully drained or would there be an auto shut down that would take place in the case I didn't manually do it?

The Samlex should have a cut-off, and the batteries will shut down via the BMS when empty.

Also, what could cause this to take place? Before going to sleep it read at 24.4 and I had no concerns because that is normal to see at nightime. Why on this night with nothing on but a fridge while we slept would my batteries be zapped down to nothing?

24.4V is a VERY low state of charge. At that level, the cells likely have only 20-25% of their capacity remaining. You have probably just been lucky up to this point. The recent rain and poor charging/lack of charging pushed you over the edge.

If I did sleep through the inverter beeping (or is it the charge controller that beeps?), would everything still continue to run until the batteries were at nothing? My previous inverter would kill the power at a certain point if it was not manually shut down. I presumed that would be the case with this one too.

It just depends if the inverter is set to trip before the batteries do. The batteries likely cut out around 20V. The inverter may or may not disconnect above that. Some 24V inverters go as low as 19V before they cut off.

My husband was concerned about the mc4 connectors being exposed in the rain during the setup. I told him they are waterproof. He took my word for it and I know I'm right but could rain cause this type of a problem and how? It was a heavy rain. When I went to check it out I noticed one of the connectors was submersed in a puddle. I removed it from the puddle. I also noticed at least a couple didn't look like they were fully screwed shut tight because I still saw some of the thread where you twist them shut.

MC4 is rated IP67: Protected from total dust ingress. Protected from immersion between 15 centimeters and 1 meter in depth.

It's not uncommon for some of the threads to still be exposed. It depends one which wire is used and the jacket thickness. If you have the tools to tighten them, it's a good idea.

How do we troubleshoot this? What do we do? Thanks for your help!

One or more of the following is likely at play:

1) Charge voltage too low.
2) Insufficient solar to cover consumption.
3) Connection issue.

I'm fully confident that 1 and 2 are in play. #3 is uncertain. If you only changed the tilt of the panels and did not disconnect anything, I doubt there's a connection issue. Ensure that all breakers are properly closed.

If you have the ability to charge via generator, you need to do it now.

Set your charge controller to 28.8V for the time being. You need to guarantee that you're getting fully charged. If you're only charging to 26.4V, you are not getting fully charged at all.
 
but could rain cause this type of a problem and how
I’ve had water ingress problems with MC4s but I attributed that to mixing brands of connector and poorly fitting rubber compression sleeves on a 8ga 20’ premade solar cable. I could shake water out of the wires.
I initially discovered this when one string went low output.

The discharge part, though; i don’t know. An SCC shouldn’t back feed the panels I don’t think.
 
I have a solar off grid system consisting of 12 100w 12v mono panels which are set up 3s4p with an inline fus at each string, 50a circuit breaker(acts as disconnect switch), renogy 40amp mppt charge controller, goes thrpugh another 50a circuit breaker, 4 LiFeBO4 batteries 100ah 12v hooked up 2s2p, 150a class T fuse, 2000watt 24v samlex pure sine wave inverter all hooked together in that order. Then I have one hardwired outlet for appliances and I'm also utilizing the inverter plug ports too.

Everything has worked well. We just moved the panels to catch the winter sun. Then we get hit with storms and after a bunch of rain I notice no solar panel power is registering one morning. Not only that but our inverter is still on but the batteries have been drained to 0.5! They've been completly emptied! My charge controller is set to the correct parameters and will read 26.4 when there is plenty of sun, may read 25.5 if it's overcast. It drops to 24.3 at night somrtimes andcan go lower all the waydown to 21.5 and that's the max discharge it will allow before it beeps and the inverter gets shut off. I was shocked by what I saw.

This has never happened, but say I didn't hear the beeping for the shut down-would everything stay on until my batteries fully drained or would there be an auto shut down that would take place in the case I didn't manually do it?

Also, what could cause this to take place? Before going to sleep it read at 24.4 and I had no concerns because that is normal to see at nightime. Why on this night with nothing on but a fridge while we slept would my batteries be zapped down to nothing?

If I did sleep through the inverter beeping (or is it the charge controller that beeps?), would everything still continue to run until the batteries were at nothing? My previous inverter would kill the power at a certain point if it was not manually shut down. I presumed that would be the case with this one too.

My husband was concerned about the mc4 connectors being exposed in the rain during the setup. I told him they are waterproof. He took my word for it and I know I'm right but could rain cause this type of a problem and how? It was a heavy rain. When I went to check it out I noticed one of the connectors was submersed in a puddle. I removed it from the puddle. I also noticed at least a couple didn't look like they were fully screwed shut tight because I still saw some of the thread where you twist them shut.

How do we troubleshoot this? What do we do? Thanks for your help!
When you say full sun reads 26.4V WHERE is it reading that? Battery level? PV outputV? This is important.
 
PST-2000 Info
Note the LOW DC INPUT VOLTAGE SHUTDOWN = 20.0V +/- 0.2V.
1640429842782.png
7.13 USE OF EXTERNAL PROGRAMMABLE LOW VOLTAGE DISCONNECTS The above ambiguity can be removed by using an external, programmable Low Voltage Disconnect where more exact voltage threshold can be set to disconnect the battery based on the actual application requirements. Please consider using the following Programmable Low Battery Cut-off / “Battery Guard” Models manufactured by Samlex America, Inc., www.samlexamerica.com
- BG-40 (40A) – For up to 400W, 12V inverter or 800W, 24V Inverter
- BG-60 (60A) - For up to 600W, 12V inverter or 1200W, 24V Inverter
- BG-200 (200A) - For up to 2000W, 12V inverter or 4000W, 24V Inverter
For the batteries to cut off they reached Low Volt Disconnect more than likely before the Inverter reached its cut-off point of 20.0V which is 2.500V per cell in a 24V/8S Battery.

You do not mention if this is a DIY Battery or if Commercial/Prebuilt, nor what BMS is used. In most cases, once the LVD the BMS will wake momentarily to see if there is incoming juice to charge (milliseconds only) so you will have to apply charge and within a few minutes the batteries should begin taking charge.

NOTE: Because the inverter discharged fully as it shut down while running, the restart from battery will pull a huge initial start to precharge its capacitors.

Regarding the Solar" First check breakers & fuses as applicable. If they are OK, turn them OFF, then check all the MC4 Connections to ensure they are good & tight, if it's necessary to open them, use ONLY the Correct Tool to open them (too many get mangled up with the wrong tool and it does not take much at all) The O-Rings can get twisted/rolled which may cause issues with the seal. NB: Not all MC4 connectors are the same, so there is a bit of difference between them. IF it all looks good and checks out then it is likely npt the problem.

SCC Issue.
As the batteries likely are in LVD they of course will not register any voltage. The SCC has no Reference Voltage to see before starting. Most SCC's will not operate without the Reference Voltage being there so that they set to the correct voltage (most can do 12,24,48V). If this is the case, the SCC will not come online till it can see 20V+ on the battery side. So once you start charging teh batts the SCC can be started and it can add to the charge coming in, PROVIDED you do not exceed the Amp Limits of the BMS (likely 50A Charge Rate max).

It is more than likely you had several days of Low Generation from the panels (more or less what you said in Post 1) while continuing to draw power leading to the cutoff. It is more than likely Coincidental that the batteries drained shortly after making adjustments to the panels, consider that they were more than likely in a lower SOC at the point when you adjusted your panels and just never regained enough afterwards.

Hope it helps, Good Luck
 
do not mention if this is a DIY Battery or if Commercial/Prebuilt, nor what BMS is used. In most cases, once the LVD the BMS will wake momentarily to see if there is incoming juice to charge (milliseconds only) so you will have to apply charge and within a few
The batteries are Amperetime bought off Amazon.
 
My husband was concerned about the mc4 connectors being exposed in the rain during the setup. I told him they are waterproof. He took my word for it and I know I'm right but could rain cause this type of a problem and how? It was a heavy rain. When I went to check it out I noticed one of the connectors was submersed in a puddle. I removed it from the puddle. I also noticed at least a couple didn't look like they were fully screwed shut tight because I still saw some of the thread where you twist them shut.
Not really adding to anything said but reinforcing. Sometimes with MC4 connectors, I can’t get them to tighten all the way. Usually, not all the time. When I can’t its only a thread or so. This puzzles me. I use the same type and manufacturer of 10 AWG PV wire. I honestly don’t think anything of that. I consider it normal. Even if I tighten it all the way, its extremely hard to do so.

If I find an MC4 connection that has several threads exposed, I think that was hand tightened only and the tool was not used to finish the job.

If it makes you feel better, you can go back and touch where the wire enters the connectors with some sealant like DICOR Lap sealant. I don’t do that with MC4 connectors, but I do that with cable glands.

I can’t think of any, affordable, better solution than MC4s. I use Anderson Powerpole Quick Disconnects for some solar panels on a portable setup, but not when weather proofing matters. Someone else claimed to cut MC4 connectors off, butt splice them together, and then wrap in waterproof tape, which I think is a terrrible idea and worst than when he started.
 
I can’t think of any, affordable, better solution than MC4s. I use Anderson Powerpole Quick Disconnects for some solar panels on a portable setup, but not when weather proofing matters. Someone else claimed to cut MC4 connectors off, butt splice them together, and then wrap in waterproof tape, which I think is a terrrible idea and worst than when he started.
Not only that but you will void any warranty by cutting of the factory installed connectors.
 
You may want to get a quality battery monitor & shunt. I really like the Victron Smartshunt or BMV712. Knowing the current battery level is important to prevent shutting down the battery (and all the hassles of them bringing it back up).
 
have the ability to charge via generator, you need to do it now.
I have a generator, yes. The batteries will need to be separated from the 2s2p they are in right now, right? What is the order of disconnecting cables?
1) switch off breakers
2) disconnect scc and inverter cables

then do I unhook the series cables first or the parallel cables first? Or do I just unhook black first and then red?
 
1) Charge voltage too low.
2) Insufficient solar to cover consumption.
3) Connection issue.

I'm fully confident that 1 and 2 are in play. #3 is uncertain. If you only changed the tilt of the panels and did not disconnect anything, I doubt there's a connection issue
The panel location was changed and they were disconnected at the time. But theyve been operating for about three weeks already like that.

I did notice on the scc it will read the batteries at 0.7 now during the day, then shuts off at night. So it appears maybe a trickle of power is coming in. The light which signals we are receiving solar power does not light up however.
 
Do you have a 24v charger? If so… don’t disconnect the batteries just connect to the main pos & main negative

If you just have a 12v charger disconnect the series and connect all batteries into parallel and get them charged up.
 
Disconnection order does not matter, just be careful not to let cables touch anything or touch your wrench to anything but the intended connection. This is no small point, there is a lot of energy ready to be released at the touch. If you're not comfortable with the process, get someone who is to help. I give my opinion assuming you built the system and are aware of the risks. (required cautions complete, we will now proceed)

There are 2 ways to proceed, depending on your equipment and need for speed. (option 1 - my recommendation) - You can charge each battery individually, then re-assemble the bank, or (option 2) - Temporarily reconfigure the bank to 4p for charging, then disconnect and reconfigure to 2S2P. This may be faster if you have a large generator and charger, and assures proper balancing. All batteries should be charged to the identical voltage before temporarily reconfiguring them to 4P for charging from the generator.

With either method, make sure your charger is able to re-start the BMS modules, as some of chargers won't start charging until they see voltage on their output leads. The actual order of dis-connecting isn't important but do it as to minimize the risk of your tools touching adjacent terminals.

Option 1: Disconnect each battery, and check it's voltage. If it's in shutdown, connect to the charger to re-set the BMS, disconnect charger after a minute and verify it's voltage, or you can go by the "charging" light or current display to verify it is indeed charging. Charge them all to 14.4v and then reconnect the parallel sets 1st, followed by the series connection and SCC/inverter. Close the breakers and you should be back online. Monitor closely to be sure all is working normally.

Option 2: Disconnect each battery, and check it's voltage. If it's in shutdown, connect to the charger to re-set the BMS, disconnect charger after a minute and verify it's voltage, or you can go by the "charging" light or current display to verify it is indeed charging. Charge them individually to a low level (12.0v is good, but less is ok if the all the BMS modules are on. You want identical voltages shown on a good quality accurate voltmeter). Connect in 4p temporarily and charge to 14.4v, or let your battery charger indicate full (if it's an automatic one). Connections should be made by connecting all 1 side (+ or -, it doesn't matter), then, one at a time connecting the other batteries. Connect the charger to 1 of the 2 center batteries to help with keeping current flow even (a minor point, but it doesn't hurt). Once fully charged, re-configure to 2s2p by creating 2 2p banks 1st, then connecting the +- bridge, verify the output voltage and polarity, then the SCC/Inverter connections. Close the breakers and you should be back online. Monitor closely to be sure all is working normally.

Ideally, most evenings, you should see 28v+ (28.8 is great) if you got a full charge from the daytime sun, otherwise you need to check your array or possibly add a few panels to bring it up to capacity for your location.

The actual order of connections isn't important as long as all batteries are in the same state of charge, or very nearly so, but when assembling a bank, you want the batteries SOC as identical as possible (read up on how to do this, it's more complex than it seems)

Merry Christmas, and let there be light!
 
Last edited:
I have a generator, yes. The batteries will need to be separated from the 2s2p they are in right now, right? What is the order of disconnecting cables?
1) switch off breakers
2) disconnect scc and inverter cables

then do I unhook the series cables first or the parallel cables first? Or do I just unhook black first and then red?

Without more information, I can't say how you would charge. The hope is that you have a 24V charger you power with the generator to charge your bank directly.

Some Samlex inverters are also chargers. You can attach the output of the generator to the AC input of the Samlex if so equipped.

The panel location was changed and they were disconnected at the time. But theyve been operating for about three weeks already like that.

Just secure all MC4 to ensure they won't be in standing water.

I did notice on the scc it will read the batteries at 0.7 now during the day, then shuts off at night. So it appears maybe a trickle of power is coming in. The light which signals we are receiving solar power does not light up however.

I suspect you may also be dealing with an imbalance issue. Recommend that you break the 24V battery down and connect all 4 in parallel as 12V. Place a 12V charger on (+) on the first battery and the (-) on the fourth battery. Charge until all batteries are full. This is something that should be done before the batteries are placed in a 24V configuration.
 
No.
If an expendable/consumable parts needs replacing you do it.
No? So apparently you know the policies of all PV manufacturers. I doubt they consider the connectors expendable or consumable. They aren't like tires on a car. I'd like to see in writing where any Mfg. allows you to cut the connectors off their modules.
 
No? So apparently you know the policies of all PV manufacturers. I doubt they consider the connectors expendable or consumable. They aren't like tires on a car. I'd like to see in writing where any Mfg. allows you to cut the connectors off their modules.

It's about priorities. For someone pleading for help because their system is offline, they're probably not worried about voiding the warranty on a $100 panel vs. getting it fixed ASAP.

Please consider if your input to this thread is actually helping the OP.
 
consider if your input to this thread is actually helping the OP.
Thank you. You understood the point.

I’ve gotten to a point where I’m not worried about things like this, though. I have hung here long enough to figure out who the brains are.
This forum has a higher occurrence of critics than other forums (not solar) I hang which is unfortunate. So far I’ve been called stupid several times, a liar twice, and recently told I don’t know what I’m talking about. While it’s true I have a lot to learn and I’m no electrical guru, even if I am an idiot I can’t make a wattmeter read any differently than reality, and nothing electrical I’ve ever done has burned up.
I doubt they consider the connectors expendable or consumable
Then why do they (PV resellers) sell replacement MC4s?

When something is broken you fix it.
 
Please… if something bothers you about a post, report it. Do NOT respond to it.
Thank you. You understood the point.

I’ve gotten to a point where I’m not worried about things like this, though. I have hung here long enough to figure out who the brains are.
This forum has a higher occurrence of critics than other forums (not solar) I hang which is unfortunate. So far I’ve been called stupid several times, a liar twice, and recently told I don’t know what I’m talking about. While it’s true I have a lot to learn and I’m no electrical guru, even if I am an idiot I can’t make a wattmeter read any differently than reality, and nothing electrical I’ve ever done has burned up.

Then why do they (PV resellers) sell replacement MC4s?

When something is broken you fix it.
Your original reply to my comment was very condescending I felt the need to reply. As long as you want to continue to derail the OP then I will just say the MC-4 connectors aren't being sold as replacements. Have you ever needed to make extension cables for a PV install? If not, then you can't have much experience in your little 12 volt installs.
 
Back
Top