Built A tiny home, but it has solar issues

[chrisski]

Looks like you found the problem. A black wire from the shunt to the bat neg of the charge controller will give SCC what it needs to charge.

Whether that’s the MPPT or PWM, should not matter. Without that bat - attached, it should have never worked.

I don’t like the idea of multiple lugs to the shunt. I connect each lug to its own stud on a busbar to split at a busbar. The only thing that would change that for me would be if the documentation on the shunt said four lugs connected there is fine.

Really sounds as if you know your system.

[The_realTW]

Chrisski, and anyone else, here is an in depth trace of the wiring

https://youtu.be/M_Fl4il-WCc

[The_realTW]

Wow first off thanks for all the help, and yes I know this stuff carries risk, I got shocked plenty (mostly from AC) when wiring the tiny home. Ill take these one at a time in quotes so we are on the same page. I do want to point out that SOMEHOW the SCC has to be sending current to the batteries, its full darkness here, my SCC is showing the panels asleep (its a symbol of the moon) and I am still using power, both AC and DC, I simply cannot see how that would be possible otherwise. I will look back in the thread on the photos, you have a sharp eye. The rest will be detailed in the quoted blocks, thanks so much. EDIT: I looked at the photo you describe, and I can see how it looks confusing, but there was no sixth wire there, just shadows.

On the original post (Post #1) on this thread, looks like the MPPT has six wires going into it, but at the close up of the MPPT with the picture on the bottom of page 9, post #135, looks like there is only five. To me, it looks like there is one wire that comes out from the left side of the MPPT in post #1, that I can’t see on the bottom of Page 9 post #135.

I’m a little reluctant to say hook a new battery wire in for the PWM. Aside from the fact that I go into a great bit of effort to calculate how thick these wires should be to prevent voltage loss and wires shorting out because they’re too small, you’d need to be sure there’s not a wire floating around in the trailer wall that is hooked directly to the battery. To me there’s a lot more testing I would do than I list below to be sure I’m not going to start a fire.

There is a photo displaying that below, a for the wire thickness, I would just use the same stuff that we wired with in the first place, I have extra remnants.

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Start by measuring VDC across the PV+ and PV- while the panels are on. There should be something above 18 if there is sunshine. If not, I would not do the rest because when I look at the labeling on your MPPT controller, the wiring is just not logical. I don’t understand why they would group the PV / Battery and load the way they did. It’s just different than the four controllers I have. Mine all have PV +/-, Battery +/-, and if applicable load +/-. That and your panel is not labeled PV+. That make me think the labeling on the MPPT could just be wrong.

I did that test today when I took the cover off the SCC, I measured across the PV+ - PV - and got 18.1 - 18.2 volts. As for the wiring on the MPPT I might be able to explain that , the PV + label on the inside panel was YELLOW, making it impossible to read, so Drew wrote PV + on it with black marker, but the PV+ wire is in the right spot, see a photo of the panel with cover off under this paragraph. Look closely and you will see the YELLOW writing barely.

IMG_8078.JPG

With battery power removed, as in cables disconnected, and solar panels off, as in circuit breakers off, so that everything in the trailer is off, including powering down the inverter, I would disconnect the PV wires and keep then reasonable far apart and then have someone turn the circuit on while the wires are at least on inch apart with the multimeter set to DC to see if I get voltage thorough the solar panels. I don’t know the short circuit voltage of your panels, but you should get at least 18. Trip the breaker so there’s no PV power and insert the wires back into the old SCC. My wires will Arc from about 1/4” and arcing is a risk in DC so you don’t want to leave those wires dangling. Voltage from the panels shows the panel wiring is good.

I am currently solo and have no one to help me but I will say this I have already tested those wires in and OUT of the SCC Bare wires read about 18V or so , short circuit I believe is 36.6 V on the trina, I saw a slight bit of arcing when i put the wires back in yesterday.

I don’t think you have a circuit breaker, so you could have someone cover the panels with cardboard to ensure it does not blow away and make the circuit live at a bad time. Have him take it on and off.

I have the converter box , all the breakers are inside there. While I cannot have someone help me at the moment, I an do some testing myself.

[QUOTE=chrisski;n425393Provided the panels work, the next step would be figuring out where the mystery negative wire went. [/QUOTE]

IF you look in this photo (taken the day after the solar was installed , you can see there never was a - to the battery from the SCC

pvwall-closeup.jpg

With the system still completely off, and batteries still disconnected and no PV power, I’d ohm the battery cables. I had made about a 20’ test lead that is reliable enough that when I put one end on the + battery lead, +end on the wire entering the SCC Bat + and for the continuity test, the multimeter will beep. The beep is good.

I will perform that test

Some of that can be dangerous. I tried the continuity test over a live tripped breaker before, and this is bad and there was a whole lot of sparks. THat’s how I found out a continuity test would complete a closed circuit so it should not be live. Going any further than what I’ve mentioned has a risk of doing the same if I say something wrong or incomplete or you misunderstand something.

I do understand about 95% of what your telling me I assure you, also something that came to mind tonight, could the negative and positive current be flowing BOTH ways on the battery? if so could I not just run a wire from BAT - on the PWM to the shunt, would that not send electricity into the battery along the wire, the Positive side goes that route???

Ill be making a video, just so you know exactly what is going on

I await your reply, that negative wire is going to have to go somewhere, otherwise I cannot install the new PWM

[chrisski]

On the original post (Post #1) on this thread, looks like the MPPT has six wires going into it, but at the close up of the MPPT with the picture on the bottom of page 9, post #135, looks like there is only five. To me, it looks like there is one wire that comes out from the left side of the MPPT in post #1, that I can’t see on the bottom of Page 9 post #135.

I’m a little reluctant to say hook a new battery wire in for the PWM. Aside from the fact that I go into a great bit of effort to calculate how thick these wires should be to prevent voltage loss and wires shorting out because they’re too small, you’d need to be sure there’s not a wire floating around in the trailer wall that is hooked directly to the battery. To me there’s a lot more testing I would do than I list below to be sure I’m not going to start a fire.

================

Start by measuring VDC across the PV+ and PV- while the panels are on. There should be something above 18 if there is sunshine. If not, I would not do the rest because when I look at the labeling on your MPPT controller, the wiring is just not logical. I don’t understand why they would group the PV / Battery and load the way they did. It’s just different than the four controllers I have. Mine all have PV +/-, Battery +/-, and if applicable load +/-. That and your panel is not labeled PV+. That make me think the labeling on the MPPT could just be wrong.

With battery power removed, as in cables disconnected, and solar panels off, as in circuit breakers off, so that everything in the trailer is off, including powering down the inverter, I would disconnect the PV wires and keep then reasonable far apart and then have someone turn the circuit on while the wires are at least on inch apart with the multimeter set to DC to see if I get voltage thorough the solar panels. I don’t know the short circuit voltage of your panels, but you should get at least 18. Trip the breaker so there’s no PV power and insert the wires back into the old SCC. My wires will Arc from about 1/4” and arcing is a risk in DC so you don’t want to leave those wires dangling. Voltage from the panels shows the panel wiring is good.

I don’t think you have a circuit breaker, so you could have someone cover the panels with cardboard to ensure it does not blow away and make the circuit live at a bad time. Have him take it on and off.

Provided the panels work, the next step would be figuring out where the mystery negative wire went.

With the system still completely off, and batteries still disconnected and no PV power, I’d ohm the battery cables. I had made about a 20’ test lead that is reliable enough that when I put one end on the + battery lead, +end on the wire entering the SCC Bat + and for the continuity test, the multimeter will beep. The beep is good.

Some of that can be dangerous. I tried the continuity test over a live tripped breaker before, and this is bad and there was a whole lot of sparks. THat’s how I found out a continuity test would complete a closed circuit so it should not be live. Going any further than what I’ve mentioned has a risk of doing the same if I say something wrong or incomplete or you misunderstand something.

[The_realTW]

With the load wires dummy wires to nowhere, and no negative battery wire ever attached, I can only think if it ever was charged, perhaps the current flowed through some SCC ground point. I grounded mine with the green 8 AWG grounding wire.

The only wires that go to the negative are the ones you saw in the video, the big black heavy gauge wire coming into the tiny home, that goes to the shunt, then the other side of the shunt goes to the inverter. Nothing ever travels outside the tiny home except on that wire (for the ground).

For wiring, are you planning on removing the MPPT for the test and installing this? If so that could make attaching the PWM easier. Still will need a way to get battery negative connected to the PWM.

I was hoping you could tell me, I do plan on attaching all the wires currently in the MPPT into the PWM, I can always swap the controllers back. I am not sure how we are getting juice to the battery via the - wire. Are you telling me you do not think the batteries were ever being used, then where has the power been coming from , I am seriously lost now. If you like I can make you another more close up video of the system, just let me know. I plan on trying to troubleshoot this tomorrow.

I need to make some forward progress on this stuff, as i am getting tired of running the car all night to charge the batteries from the isolation system.

[chrisski]

With the load wires dummy wires to nowhere, and no negative battery wire ever attached, I can only think if it ever was charged, perhaps the current flowed through some SCC ground point. I grounded mine with the green 8 AWG grounding wire.

For wiring, are you planning on removing the MPPT for the test and installing this? If so that could make attaching the PWM easier. Still will need a way to get battery negative connected to the PWM.

[The_realTW]

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I guess you can assume the shunt is set up correct.

Is it possible the negative wire pulled out the terminal and back into the wall? I don't have a schematic, but without that battery negative attached, I don't see how the battery gets any charge at all, except perhaps it being connected to a frame ground at some point and somehow leaking through the load terminals.

it is not in the wall, it was never placed in the chain to begin with, also as for what you said about the load terminals, if your referring to the "load terminals" on the SCC, those go nowhere but to covered wires, I set them up but nothing was ever hooked up to them. I am at a loss as to where the 12V - is going as well, which may be the entire problem in the first place.

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I really think when you set the PWM Charger up, if the old SCC is out of the picture, you'll see some charging amps. Dave may have said 20-30 amps, but I think it will be around 10-15 amps of 12 volt charging at high noon.

The PWM charger I have is rated for 60 amp charging current, I would expect to see at least half that if not more. I show pics in the post above this one.

When you get the PWM charger, take a look at the max input. This is the limit that can't be exceeded for your 12 volt system. Most PWMs are built to have a max voltage of around 20 VDC input for a 12 volt system. A lot of panels I look at are designed not to produce more than 10 amps. I think your rooftop panel is 300 watts, so my guess is that panel alone may put out 30 volts at 10 amps and may not work with the PWM. If that is the case, you can take the big panel out of the system and just use the smaller 100 watt helper panel. It will not be the amount of power you like, but if the panel puts out around 18 volts and 4 to 6 amps with direct sunshine, you've verified most of your system.

Same as above, I think this PWM can handle the Trina and the "helper" 100 watt, but again this is only a test. Once I figure out where the - wire is run to, ill start the testing.

[The_realTW]

Ok everyone, I got the PWM controller, this thing is tiny. Obviously the Solar + - go into the respective slots, and the battery +, but where do i run the battery -, the other one never had one. Am I creating a new wire run back to the shunt?

I would appreciate any help.

BTW this thing says it uses less then 10MA to run when it is idle, I have a feeling that is way less power draw then the one on the wall.

Ill standby so I do not fry anything, photo of the charge controller is attached

IMG_8076.JPG



IMG_8075.JPG

[chrisski]

Yeah I am not sure, I just checked both panels from their leads, separately , and neither has any voltage coming off of it, it is cloudy but the SCC says 15 V coming in with 1 watt,

I checked both batteries with the meter, each is measuring 5.85 DC volts, however only .5 amps, it is possible the meter I bought (for 89.00!) is bad, and if that is the case all my measurements are invalid. We will pick this up tomorrow when it is sunny, and the PWM is here. Although I confess I know not how to wire it, but I will give it the ol college try!

Thanks again

BTW shunt is the first thing in the chain when the negative cable comes in from the battery

=======

I guess you can assume the shunt is set up correct.

Is it possible the negative wire pulled out the terminal and back into the wall? I don't have a schematic, but without that battery negative attached, I don't see how the battery gets any charge at all, except perhaps it being connected to a frame ground at some point and somehow leaking through the load terminals.

========
I really think when you set the PWM Charger up, if the old SCC is out of the picture, you'll see some charging amps. Dave may have said 20-30 amps, but I think it will be around 10-15 amps of 12 volt charging at high noon.

When you get the PWM charger, take a look at the max input. This is the limit that can't be exceeded for your 12 volt system. Most PWMs are built to have a max voltage of around 20 VDC input for a 12 volt system. A lot of panels I look at are designed not to produce more than 10 amps. I think your rooftop panel is 300 watts, so my guess is that panel alone may put out 30 volts at 10 amps and may not work with the PWM. If that is the case, you can take the big panel out of the system and just use the smaller 100 watt helper panel. It will not be the amount of power you like, but if the panel puts out around 18 volts and 4 to 6 amps with direct sunshine, you've verified most of your system.

[The_realTW]

I don't know why there is no battery negative going into the battery-. You can disconnect the batteries and panels and try to do a continuity test to see which is hooked to the battery. On my PWM SCC that has Bat + and Bat -, there needs to be a connection to each before I hook up the SCC or load. Owners manual should say for sure, but that seems to be the problem.
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I really like Dave's idea of a PWM controller. Get the battery wired first, set the voltage, and then hook the panels up. You may have power.
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The shunt should be the first thing on the negative battery cable. Don't know how my spell check got "moons" out of that.

Yeah I am not sure, I just checked both panels from their leads, separately , and neither has any voltage coming off of it, it is cloudy but the SCC says 15 V coming in with 1 watt,

I checked both batteries with the meter, each is measuring 5.85 DC volts, however only .5 amps, it is possible the meter I bought (for 89.00!) is bad, and if that is the case all my measurements are invalid. We will pick this up tomorrow when it is sunny, and the PWM is here. Although I confess I know not how to wire it, but I will give it the ol college try!

Thanks again

BTW shunt is the first thing in the chain when the negative cable comes in from the battery

[chrisski]

I don't know why there is no battery negative going into the battery-. You can disconnect the batteries and panels and try to do a continuity test to see which is hooked to the battery. On my PWM SCC that has Bat + and Bat -, there needs to be a connection to each before I hook up the SCC or load. Owners manual should say for sure, but that seems to be the problem.
=====
I really like Dave's idea of a PWM controller. Get the battery wired first, set the voltage, and then hook the panels up. You may have power.
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The shunt should be the first thing on the negative battery cable. Don't know how my spell check got "moons" out of that.

[The_realTW]

Ok I still have a couple tests left, ill get back at this thread when finished

https://www.windynation.com/cm/Testing%20a%20Solar%20System_R1.pdf

[The_realTW]

UPDATE: Further information

Solar troubleshooting



Path to: pos-neg from solar mainline input from roof

Amps: .5DC

Volts: 19.8DC Consistent





Path to: right side negative shunt -right side 500A fuse block

Amps: .20 DC

Volts: 11.8 DC





Path to: Left side negative shunt - left side 500A fuse block

Amps: .38

Volts: 11.7 DC





Path to: Pos-neg inverter terminals

Amps: .32

Volts: 11.7 DC





Path to: inverter out to converter

Amps: variable

Volts: 122.2 AC





Path to: Battery pos from SCC - battery

Amps: N/A

Volts: N/A



There is no lead coming from Battery NEG on the SCC, therefore I was not able to test voltage to battery and honestly not sure how voltage is getting back to the batteries at all.



See photo

IMG_8062.JPG

[The_realTW]

Sorry it has taken some time to get back, lots has been going on. Ill update you after I answer your questions.

Here’s my comments. The most important is the last. The battery looks flooded lead acid to me.

It is Flooded lead acid, and I made the change in the SCC, no help there.

Do you have a shunt? This measures power to the battery. The SCC only gives amps from the SCC, not how many are diverted to your equipment and how many are diverted to charge your battery. An improperly connected shunt would give bad battery charging rate.

There is a shunt in the chain, it is clearly shown in the video at 04:38, I do not know if it is hooked up correctly as Drew (the solar installer) hooked it up.

Moons is the first thing on the negative wire from the battery. Yours should be there if you have one

I have been scratching my head trying to figure out what "moons" means, can you clarify.

The equipment you have on the roof will shade the panel, perhaps half the day. I check my panels by putting them in sunshine and look at the battery monitor and when the shadow of my head goes on the panel, I lose 80% of the output. I don’t think you’ve got an amp meter to measure, but without one I’ll give you that for reference. I think you said the cable is tucked under the panel, but if it wasn’t that will seriously effect output.

I have purchased a new amp meter, see below in the update for a photo, I am unfamiliar with its exact functions however so I will need some help with that.

For the charge cable on the roof, I’d zip tie that at at various places and secure it to the roof with cable holders with a peel off sticky on the back. Cleaning the surface is key to getting it stick, but if cleaning doesn’t work for me, I secure it with Dicor roofing tape.

I guess its not shown in the video, but that cable runs through a steel channel, it would be impossible and impractical to put anything more around it, there is only a 1 foot section between the end of conduit to the area where the grommet is for it to go inside.

I did not expect the 15 amp shore power plug to be-a female normal wall receptacle, but have honestly not seen a 15 amp receptacle before.

We did that for ease of use, without any strange connectors being needed. The tiny home only has a 20 amp wiring and service so we used the 15 amp plug because the generator uses the same type of receptacle and also the generators MAX load is 16 amps.

I would also wrap the battery cable with split wire loom from the battery, through the wall to just above where it enters the trailer. Gives it an extra bit of protection over the years so it does not wear through. In my RV, it is routed through electrical conduit.

I wanted to do that, so many things I wanted to do, and surprisingly that cable is holding up well, it is some of the thickest gauge cable I have ever seen, but yes it will be tended to in the future.

I don’t know what SLD stands for, but your batteries to me look like flooded lead acid. It looks like you could unscrew the caps and add water. I tried looking it up online, but other than available at COSTCO, a quick search didn't say for sure. If they are FLA, they should never go below 50%. 15% to 20% daily kills them.

A google search on Renogy's website reveals that SLD means "Sealed", I do believe they are FLA and are currently at 35% so yes I know its killing them. I am going to explain further below.

UPDATE 04/27/21

It has been a busy week and I wanted to update you all on what is going on with the solar.

First off I had an interesting conversation with Axiom Solar out of Vancouver, they sell the SCC that is in my system. Dave said he couldnt imagine a charging current of 0.04a or the controller always being in MPPT mode. To troubleshoot the system I have ordered a basic PWM controller for around 25 dollars that should allow us to test if that component is the cause of this issue. It will arrive tomorrow. Dave said that SCC should be giving off AT LEAST 25-30 amps to the battery, and receiving at least 300 watts and 30 volts from the panels. If I can solve the SCC issues I plan on buying 4 100 watt flexible panels and a 4 to 1 MC4 splitter that will run into a 3-1 splitter. This would give me about 800 watts (with line loss factored in) The four new panels would be portable and only out when I was stopped at a location. Again priority is to figure out the current issue first.

The solar panels are no longer sending any wattage to the SCC, it is unknown why this is. Last night I was awoken 4 times to alarms going off for LVDC , Currently it is partly cloudy but really WARM (81 in Nebraska) and the weather has done a complete 180 from last week.

I went out and purchased a Ames clamp meter (yes I know it is not a Klein or a Fluke) but I am not familiar at all with its operation. Also I purchased a "Kil a watt" plug which should help figure out the audit, my thought is if i plug everything into it for 1 hour, that should get me base usage, but I know that is jumping the gun.

So this is where I am at, here is a photo of the clamp meter and the kil a watt device, I would be happy to execute any tests you guys think are necessary, as soon as someone lets me know what they want to hear or need. I am available all day today to test.

let me know

thanks again!

IMG_8058.JPG

IMG_8057.JPG

[The_realTW]

Chrisski, I’m going to get back to everything tomorrow but here is something I found in the MPPT manual

0F02C3B9-E60E-4E1D-8FE9-DB284BC7ACE5.jpeg